EFFECTS OF TELLURIC CURRENTS ON ELECTRICAL NANOTECHNOLOGY IN NAIROBI CITY AND KAJIADO COUNTIES, KENYA
OKOTH COLLINS ODHIAMBO (BSc. TIE)
I56/CE/32302/2015
A thesis submitted in partial fulfillment of the requirements for the award of the Degree of Master of Science (Electronic and Instrumentation) in the School of Pure and Applied Sciences of Kenyatta University
September, 2019
DECLARATION
This thesis is my original work and has not been presented for the award of a degree or other awards in any university.
Okoth Collins Odhiambo Signature Date
Department of physics
Kenyatta University
I/We confirm that the work reported in this thesis was carried out by the student under my/our supervision.
SUPERVISORS
Dr. Raphael Nyenge Signature Date
Department of Physics
Kenyatta University
Dr. Mathew Munji Signature Date
Department of Physics
Kenyatta University
DEDICATION
I dedicate this thesis to my wife and children for their endless love, support and encouragement.
ACKNOWLEDGEMENT
Foremost, I thank God for the good health and the opportunity to accomplish my research against all challenges. Thanks to Kenyatta University for the study opportunity.
I would like to sincerely thank my supervisors, Dr. Raphael Nyenge and Dr. Mathew Munji for their valued comments, opinions and suggestions through the study. I also recognize the lecturers in the department of Physics at Kenyatta University who patiently guided me through their recommendations, constructive discussion during research.
I thank Multimedia University of Kenya, specifically Faculty of Engineering and Technology for allowing me an enabling environment to conduct the research.
To all my family members and friends, I thank you for all manner of support you gave me throughout my research.
TABLE OF CONTENTS
TABLE OF CONTENTS v
LIST OF TABLES vii
LIST OF FIGURES ix
ABREVIATIONS x
ABSTRACT xi
CHAPTER 1 1
INTRODUCTION 1
1.1 Background Information 1
1.2 Problem Statement………………………………………………………………………….5
1.3 Objectives of the Research 5
1.3.1 General Objective 5
1.3.2 Specific Objectives 5
1.4 Rationale of the Study 6
CHAPTER 2 7
LITERATURE REVIEW 7
2.1 Introduction 7
2.2 Previous Study on Telluric Currents 7
CHAPTER 3 12
THEORY OF TELLURIC CURRENTS 12
3.1 Space phenomena 14
3.1.1 Geomagnetically-induced currents 15
3.1.2 Cosmic-particle flux 19
3.1.3 Planetary magnetic-field plasma 24
3.2 Atmospheric phenomena. 26
3.2.2 Traveling ionospheric disturbances 27
3.2.3 Lightning strikes 32
3.2.4 Whistler induction 35
3.3 Oceanic phenomena 39
3.3.1 Electrochemical effects in the ocean 40
3.3.2 Metabolic electrochemistry in the ocean 46
3.4 Surface phenomena 48
3.4.1 Artificial signals 50
3.4.2 Metabolic electrochemistry in soil 51
3.5 Measurement Methods 52
CHAPTER 4 54
MATERIALS AND METHODS 54
4.2 Data measurement 56
4.3 Data Reduction 58
4.4 Data Processing 58
4.5 Data Presentation, Analysis and Interpretation 59
CHAPTER 6 83
REFERENCES 84
LIST OF TABLES
Table 1. Telluric currents measured at 1m, 5m and 10 meter profiles respectively in Nairobi County.
Table 2. Telluric currents measured at 1m, 5m and 10 meter profiles respectively in Kajiado County.
Table 3: Average telluric current potential at profiles 1m, 5m and 10m in Kajiado & Nairobi counties respectively
LIST OF FIGURES
Figure 1: Embakasi Location Map
Figure 2: Ongata Rongai Location Map
Figure 3: Block diagram of telluric current measurement setup
Figure 4. Scatterplot of telluric current against time at 1m profile in Nairobi County
Figure 5. Scatterplot of telluric current against time at 5m profile in Nairobi County
Figure 6. Scatterplot of telluric current against time at 10m profile in Nairobi County
Figure 7. Scatterplot of telluric current against time at 1m profile in Kajiado County
Figure 8. Scatterplot of telluric current against time at 5m profile in Kajiado County
Figure 9. Scatterplot of telluric current against time at 10m profile in Kajiado County
Figure 10: An electronic circuit before subjected to telluric currents
Figure 11: Cumulative effect of telluric currents on a buried electronic system
Figure 12: (a) Typical voice signal over wired
Figure 12: (b) Voice signal over communication line communication lines exposed to telluric currents.
ABREVIATIONS
2D – Two Dimension
EMC – Electromagnetic Compatibility
GDS – Geomagnetic Depth Sounding
GIC – Geomagnetically Induced Currents
ICT – Information and Communication Technology
LED – Light Emitting Diode
MoEP – Ministry of Energy and Petroleum
RMS – Root Mean square
VLSI – Very Large Scale Integration
ABSTRACT
The need for electrically safe and reliable electrical and electronic devices or systems is growing in many markets around the world, such as industrial and manufacturing, automotive, medical, energy, environmental science, information and communication technology and smart grid applications. The designers and end-users of these devices or systems are counting on newer technologies that are electrically safe, distortion free and deliver higher accuracy that allows operation in less than ideal conditions. One of the most effective areas is the nanotechnology, the science that involves the study and application of extremely small systems and can be used across the entire science field. This research investigates the amplitudes of telluric currents in Embakasi, Nairobi and Kajiado counties , considering an area of 10000 m2 due to limited space available in each location, through measurement of telluric currents by use of EX542:12 multimeter and analyzing the quantities using analytical scientific software known as Statistica, with the intention of providing measures of minimizing the extent of unnecessary electrical hazard posed by telluric currents to miniaturized electrical, electronic and telecommunication devices or systems that are based on nanotechnology. By identifying the amplitudes of telluric currents, it is possible to gather useful data that could be used to analyze and minimize chances of subjecting miniaturized electrical, electronic and telecommunication devices or systems to this electrical hazard, hence safe electrical operation environment. The choice of areas of study is advised by higher concentration of underground installations in Embakasi in relation to Ongata Rongai, hence basis of telluric currents measurement comparison.
CHAPTER 1
INTRODUCTION
1.1 Background Information
The earth, atmosphere, ocean and sea are known to have their electrical characteristics which are either static or dynamic. For the atmosphere, it is known that the ionosphere and the clouds in the troposphere cause complicated electrical processes leading to discharges that are in elves, sprites, blue jets, other aural electro jets and lighting. Movement of these charges causes current flow in the different segments of the earth thus causing electromagnetic induction in any conducting object such as the ground and the seawater (Russell, 1986; Engebretson et al., 1995); Helman, 2014). This therefore causes telluric currents to flow.
The main causes of telluric currents are natural causes and as well as human undertakings. Human operations that may lead to rise of telluric currents include cathodic protection in underground and submarine metallic structures, electromagnetic radiations as a result of both overhead and underground electric power transmission, On-ground activity, such as from electric trains and d.c electrical field designed to remove contaminants from soils.
(Bilal, 2013), Telluric currents have a very complex pattern of interaction. Telluric currents flow near the surface of the ground over a large area and they have very low frequency.
The electric potential difference on the earth’s surface can be measured at different points, making it much easier to calculate the amplitudes of the telluric currents. For exploring the structure of the earth, telluric and magneto telluric methods come handy.
Telluric currents can be used for geothermal exploration, mining exploration, petroleum exploration, mapping fault zones, ground water exploration and monitoring, investigating magma chambers, and investigating plate tectonic boundaries. Also they may be harnessed to produce a useful low voltage by means of earth batteries.
The fact that planet Earth is essentially a giant magnet, a compass works because either end of its magnetized needle is constantly being drawn toward the North and South poles. Scientists believe that the Earth’s magnetization is caused by a sea of liquid metal flowing past its solid iron core, creating electric currents and, in turn, magnetic fields.
The Earth’s magnetic fields extend to the ionosphere—a layer of plasma and neutral gases about 50–500 kilometers above Earth’s surface—and the magnetosphere, which starts at the outer edges of the ionosphere and stretches many thousands of miles into space. Magnetic fields from Earth and the Sun affect the behavior of charged particles in the magnetosphere.
Earth’s magnetic field is highly conductive and carries charged particles in a predictable fashion along field lines. Starting in the early 1900s, scientists conceptualized an exchange of energy and momentum between the solar wind (a stream of charged particles emitted by the Sun that flows throughout the solar system) and our planet’s own magnetic field.
Since then, we have learned more about the distribution of field-aligned currents throughout the ionosphere. And, more recently, the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) satellite network has allowed scientists to study large-scale field-aligned currents in great detail, collecting data as often as every 10 minutes.
In a new publication, McGranaghan et al. combine data from AMPERE and a constellation of three European satellites known as Swarm to compile a data set of small-scale (up to about 150 kilometers wide), medium-scale (about 150–250 kilometers wide), and large-scale (wider than 250 kilometers) field-aligned currents.
It was found that many differences between small-scale and large-scale currents—such as their behavior, the dependence of their behavior on local time and solar wind conditions, and how closely their orientation aligns with that of the planet’s magnetic field—are not straightforward. For example, they found that small-scale field-aligned currents potentially contribute a disproportionate amount of heat to regions of the ionosphere and thermosphere (an upper layer of Earth’s atmosphere).
If future studies of field-aligned currents incorporate data from a variety of scales, scientists will be able to better understand the complexities of the space environment and the resolution needed to capture them. The researchers note that this better understanding, in combination with new and improved physics, has the potential to critically affect our understanding of the system at large
Effect of telluric currents on effect of cathodic protection of pipelines
Telluric currents causes variations in the pipe to soil potential that takes the potentials to the desired range of cathodic protections. This potential is described using various technologies created to show how design changes can influence the impact of telluric currents on cathodic protection of pipelines. Pipelines are long electoral conductors stretching thousands of kilometers through the earth’s surface and thus experiences the telluric currents induced by the outside sources. The sources discussed in this paper, shows they are either man-made like the AC power in railway system, in Nairobi, or natural like the geomagnetic disturbances in the ocean. The introduction of new high strength steels with more susceptibility in recent years a number of studies have helped to illustrate the causes of telluric currents and to show the factors controlling the size of pipe-to-soil potential (PSP) variations that they produce. Simultaneously telluric currents are being seen as more of a problem because the use of higher resistance coatings on modern pipelines has resulted in larger PSP variations than on older pipelines. Now, the introduction of new high strength steels with more susceptibility to hydrogen will place more stringent requirements on keeping PSP within narrow limits. The intention of this paper is to explain the causes of telluric currents and the factors influencing the PSP variations they produce so that pipeline engineers can design protection systems to mitigate these effects.
GEOMAGNETIC DISTURBANCES
Telluric currents were first observed on the telegraph system in the 1840s (see references in [2]). From the earliest accounts there was a recognition of the simultaneous occurrence between the telluric currents and fluctuations of compass needles and sightings of the aurora. Some people also noted an association between the telegraph disturbances and the number of sunspots crossing the face of the Sun. There has been a long debate about the nature of the linkages between these phenomena. Just as the requirements of navigators spurred research into the main magnetic field of the Earth, so disturbances on the telegraph helped to stimulate investigations of the magnetic field-disturbances.
The main magnetic field of the Earth and magnetic disturbances are produced by radically different phenomena. The main field is of internal origin, being generated by electric currents flowing in the molten outer-core of the Earth. Heat convection causes a circulation of the molten iron within the core. The movement of the conducting iron through the Earth’s magnetic field is presumed to generate an electric current that flows in such a way as to reinforce the magnetic field.
Magnetic disturbances are produced by electric currents flowing in the ionosphere and Magnetosphere extending from 100 km above the Earth’s surface to many thousand kilometers out into space. Every electric current produces a magnetic field and the magnetic field of these currents external to the Earth is observed at the Earth’s surface along with the Earth’s own magnetic field.
1.2 Problem Statement
Geomagnetically induced currents (GIC) flow in any conducting body as a result of surface electric field. To be hazardous to miniaturized systems, these currents have to be of a magnitude and frequency that makes the devices and electronic systems susceptible to either immediate or cumulative fault. Telluric currents cause variations in conducting structure-to-soil potentials that take the potentials outside the desired range for conducting structure protection, leading to malfunction in terms of solid state devices breaking or shorting the p-n junctions and also corrosion in pipeline installations. The research is intended to investigate the potential variations in telluric currents and their effects on miniaturized electrical, electronic and telecommunication devices and systems. This follows the increased underground electrical and telecommunications network installation in Embakasi area as compared to Kajiado.
Objectives of the Research
General Objective
The main intention of this research is to investigate the Electromagnetic Compatibility (EMC) problem through measurements of telluric currents.
Specific Objectives
To conduct measurements of telluric currents in Embakasi, Nairobi and Kajiado counties.
To determine the possible effects of telluric currents on the new generation integrated circuits (ICs), and nanostructures.
To interpret the telluric potentials measured in order to mitigate their risks to miniaturized electronic devices and systems.
1.4 Rationale of the Study
With the technological trend to miniaturization of electronic components through very large scale integration (VLSI) and nanotechnology, it is expected that equipment such as is currently used in electrical and telecommunication networks, will be very vulnerable to telluric currents.
For prediction of the effects on new electronic technologies and possible ways to operate electrical, electronics and telecommunication systems safely, there is need to determine the magnitudes of the currents in local environments. The information on telluric current is an important tool to aid such predictions and safety measures to ensure that service providers are not subjected to avoidable downtime as a result of faults caused by telluric currents.
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Telluric and magnetotelluric methods are compared from principle and application standpoints, particularly as applied to various studies, as two distinct methods: magnetotelluric by its completeness and telluric by its simplicity and economy.
Theory and practice of the relative, intrinsic and absolute ellipse methods, single station methods and hybrid magnetotelluric methods are described, emphasizing physical understanding, with a view to assisting prospective users. Qualitative and quantitative interpretation methods for two- and three-dimensional structures are discussed, with the aid of case histories.
Telluric methods are suited primarily to low-cost reconnaissance in not-too-deep sedimentary structures associated with lateral changes in electrical resistivity that are frequently encountered in petroleum and geothermal exploration.
2.2 Previous Study on Telluric Currents
Lanzerotti and Giovanni, (1986) have quoted earlier efforts in which investigations of telluric currents and their effects were carried out. Pertinent to this study are the effects on communication cables and power lines as reported by Boteler, (2003); this is an Electromagnetic Compatibility (EMC) problem. Telluric currents existing in a given setup can significantly interfere with natural systems as well as human advances. If not properly regulated, telluric currents can “pollute” the natural electrical environment. In the past studies, Geophysicists have always considered the presence of telluric currents as interference, unnatural disturbance. Practicing Engineers have always been interested in the threshold of system consistency and with system’s stability and ruggedness. In addition, technological advancements in modern systems have given higher levels of surety in terms of reliability. Therefore comparing effects experienced in various devices or systems on different occasions becomes quite challenging.
In the past, communication cables were the widely investigated and documented conducting structures with reference to telluric currents, basically, after the lighting rod, the telegraph became one of the advanced man-made electromagnetic gadget in practice. Later on, telegraph lines were progressively replaced by telephone lines; submarine cables and radio links between telecommunication networks across different geographical areas.
In summary, faults in both land and undersea conducting structures are associated with the existence of natural or human caused ground currents and should be controlled (Lanzerotti, 1986).
Induced telluric currents may lead to malfunction of power system transmission and distribution accessories such as power transformers and circuit breakers resulting to power outages.
Wallace, (1980) research of telluric currents on pipelines became relevant on the construction of Trans-Alaskan pipeline. From that study, telluric currents were considered to cause more effects on devices used as test and control gadgets apart from affecting the structure under study.
Challenges associated with naturally induced ground currents in rail infrastructure were researched. At Greenwich, effects of telluric currents were done (Burbank, 1905). The disturbance on geomagnetic observations on ground natural electric fields believed to be from a d.c source, produced as a result of rail infrastructure operations was given some serious attention in terms of research.
Both the telluric and magneto telluric methods are used for exploring the structure beneath the Earth’s surface. For mineral exploration the targets are conductive ore bodies. Other uses include exploration of geothermal fields, petroleum reservoirs, fault zones, ground water, magma chambers, and plate tectonic boundaries.
The most developed application of telluric currents is the prospecting of underground structures. The methodology is quite extensive and involving. There are two major approaches: Magneto-telluric, which is a development of the telluric method which exploits certain natural earth currents (telluric currents) that propagate as sheets over vast areas on the earth. This method can resolve geo-electric structure from tens of meters to kilometers depending upon signal frequency and resistivity of structure being studied. Hence, depth interpretation based on magnetotelluric technique data is much more definitive than that based on gravity or magnetic data as reported by Vozoff, (1972).
Another approach is Geomagnetic Depth Sounding (GDS), which is an electromagnetic method of geophysics, where it is possible to image Earth’s interior in terms of electrical conductivity based on natural geomagnetic transient variations. The method is particularly suited to map geological structures marked by large lateral conductivity contrasts as reported by Arora, (1999).
In Canada, New Zealand and Turkey, the use of naturally induced fields for underground study is being conducted (Bilal, 2013).
Detection of electromagnetic signals from space could be another application of telluric currents. The earth, its conducting structures and manmade communication networks in one way or the other may be considered as receiving antennas, necessary in observing electromagnetism and related behaviors. Telecommunication medium or structures of some lengths and size ensures analytical details in relation to electromagnetic quantity from other outside sources (Smith and Coates, 1978; Smith, 1981).
Living species responding to electromagnetic fields is a quite challenging but important field in research. A number of research attempted and done include natural electric fields induced in trees, study on natural electric fields for alignment of water bacteria (Blacmore, 1975) and study on birds relocation (Moore, 1977; Larkin and Sutherland, 1977). In controlling some aquatic species such as fish, telluric currents could be employed (Leggett, 1977; Kalmijn, 1978).
Telluric currents were widely investigated in relation to long telegraph conductors. The difficulties encountered in interpreting the origin of these electromagnetic fields could be responsible for loss of confidence among researchers in exhausting studies in this field. Large improvements now exist in data collection, data analysis, data processing and presentation. Therefore, studies in this field is heading for a significant new understanding. The data obtained from this research will be very useful to provide guidelines on proper and safe practices on installation and operation of miniaturized electrical, electronics and telecommunication devices and systems. The telluric current induced by geomagnetic storms generates secondary geoelectric storms. This motionally induced geoelectric field can be detected in the sea or inland and has potential for electrical soundings of the Earth. This is aimed at gaining an understanding of the distribution of the current signal due to geomagnetic storms. By comparing the geoelectric field during storms and at quiet times, as well as comparing the telluric current calculation results of eastern China and local stations, the following conclusions are obtained.
A large range of amplitude change ratios of geoelectric storms is affected by latitude: the amplitude ratio rises at higher latitudes, and the high-frequency composition of geoelectric storms is more complicated than that of geomagnetic storms.
The storm creates a large area of electromagnetic fluctuations, and influences the distribution of the telluric current.
On the basis of previous studies, a spatial eddy current model is used, which can explain the observation phenomena well. At the same time, a further study direction is put forward on Earth’s electromagnetism.
CHAPTER 3
THEORY OF TELLURIC CURRENTS
Whether the sources of telluric currents are internal to the crust of the earth or whether they are ionospheric, whether these sources are natural or whether they are artificial, the electro-magnetic phenomena inside the earth are the same in every case. In fact, the reasoning depends only on the requirement that the telluric current sheet be sufficiently uniform. But this uniformity is a matter of experience. Telluric prospecting proves that in large sedimentary basins this uniformity extends, in an approximate way, over a considerable expanse, often some ten kilometers in width. Such uniformity should be expected all the more if one only considers the very restricted field that enters into a magneto-telluric comparison. Artificial telluric currents, because of the relative proximity of the sources which produce them, and because of the poor degree of uniformity of the sheets associated with such artificial currents, are feared by the telluric prospectors. On the contrary, they are looked on as a blessing by magneto-telluric prospectors, because they offer sufficient uniformity to meet the requirements of the new method, and they usefully enlarge the spectrum of frequencies.
Furthermore it has been observed that the telluric current is the same as those involved in the production of alternative current (AC) in pipelines sharing a rift- of- way and a high voltage power line. Though there is no specific theory accepted to explain their locations, these problems are worse in particular places. Theoretical work has shown that pipeline potentials should have a characteristics similar to telluric currents. Concurrently, some innovative measures has provided the first observed potential profiles slong a whole pipeline.
Distributed- source transmission line (DSTL) theory was applied to the problem of modelling geomagnetic induction in pipelines. The theory also predicted that large P/S potential variations, of opposite sign, should occur on either side of an insulating flange. Independently, an observation program was conducted to determine the change in telluric current P/S potential variations and to design counteractive measures along a pipeline in northern Canada. Observations showed that the amplitude of P/S potential fluctuations had maxima at the northern and southern ends of the pipeline. Pipeline survey make successive observations at a series of locations, it is not possible therefore to tell if their positions results from change of their site or change in time. A further set of recordings around an insulating flange showed large P/S potential variations, of opposite sign, on either side of the flange. Agreement between the observations and theoretical predictions was remarkable. While the observations confirmed the theory, the theory explains how potential variations are produced by telluric currents and provides the basis for design of cathodic protection systems for pipelines that can counteract any adverse telluric effects Pipe-to-soil (P/S) potential variations resulting from telluric currents have been observed on pipelines in many locations. However, it has never teen clear which parts of a pipeline will experience the worst effects. Two studies were conducted to answer this question. Distributed-source transmission line (DSTL) theory was applied to the problem of modeling geomagnetic induction in pipelines. This theory predicted that the largest P/S potential variations would occur at the ends of the pipeline. The theory also predicted that large P/S potential variations, of opposite sign, should occur on either side of an insulating flange. Independently, an observation program was conducted to determine the change in telluric current P/S potential variations and to design counteractive measures along a pipeline in northern Canada. Observations showed that the amplitude of P/S potential fluctuations had maxima at the northern and southern ends of the pipeline. A further set of recordings around an insulating flange showed large P/S potential variations, of opposite sign, on either side of the flange. Agreement between the observations and theoretical predictions was remarkable. While the observations confirmed the theory, the theory explains how P/S potential variations are produced by telluric currents and provides the basis for design of cathodic protection systems for pipelines that can counteract any adverse telluric effects.
For the purposes of this research, any electric current in a planet or on it may be classed as a telluric current. These include:
Space phenomena
The human species has been building knowledge step by step for millennia. As we learned to speak, write and read the nature of human capital increased at a remarkable rate. Even before we ventured into space and expanded our boundaries, the technology of computers was foretelling a Knowledge explosion. Now this knowledge is expanding exponentially; in the understanding of the Earth, our Universe and other planets, for technologies in harsh environments, human. Physiology and health, and in where we came from within the Universe. The quest of space exploration has opened many new doors and stimulated the development of knowledge. Earth-observation satellites have enabled global cooperation in natural-disaster mitigation activities and the sharing of images from space with all nations. This is just one example of peaceful ventures reaching across borders, fostering feelings of a global community and providing
Opportunities for nations, companies and individuals worldwide to participate. Less altruistic is the entrepreneurial aspect of commercial space where global communications satellites enabled new companies to be formed and profits earned for the risk taken. Prize money is now being given as an incentive to push the private sector into space: the X Prize of $10 million already awarded for taking private individuals the 100 kilometres into space; the $50 million America Space Prize to spur the development of space tourism in low-Earth orbit; the more modest competition prize money to develop components for a Space Elevator. And on the other hand, the technologies developed for such space activities are in turn providing opportunities for many around the globe because of their potential application as spin-offs in non-space sectors.
Going into space requires scientists and engineers to invent, refine and adapt current and future technologies. This creative push to operate and succeed in the harsh and extreme environment of space has led to phenomenal technological developments such as micro-miniaturization, precise navigation, global communications, telescopes that see back to the beginning of time, lightweight materials and medical advances – all valuable to human existence back on earth.
3.1.1 Geomagnetically-induced currents
Electrical phenomena caused as the solar wind or space weather impact the ionosphere. The solar wind and space weather create ionospheric electromagnetic phenomena in the radio spectrum, and these disrupt communication. Eddies in the ionosphere also occur, and these create electric current from the motion of ions. This electric current affects the geomagnetic field, and the resulting geomagnetic anomalies induce telluric currents in the ground.
A time-varying magnetic field external to the Earth induces telluric currents electric currents in the conducting ground. These currents create a secondary (internal) magnetic field. As a consequence of Faraday’s law of induction, an electric field at the surface of the Earth is induced associated with time variations of the magnetic field. The surface electric field causes electrical currents, known as geomagnetically induced currents (GIC), to flow in any conducting structure, for example, a power or pipeline grid grounded in the Earth. This electric field, measured in V/km, acts as a voltage source across networks.
Examples of conducting networks are electrical power transmission grids, oil and gas pipelines, non-fiber optic undersea communication cables, non-fiber optic telephone and telegraph networks and railways. GIC are often described as being quasi direct current (DC), although the variation frequency of GIC is governed by the time variation of the electric field. For GIC to be a hazard to technology, the current has to be of a magnitude and occurrence frequency that makes the equipment susceptible to either immediate or cumulative damage. The size of the GIC in any network is governed by the electrical properties and the topology of the network. The largest magnetospheric-ionospheric current variations, resulting in the largest external magnetic field variations, occur during geomagnetic storms and it is then that the largest GIC occur. Significant variation periods are typically from seconds to about an hour, so the induction process involves the upper mantle and lithosphere. Since the largest magnetic field variations are observed at higher magnetic latitudes, GIC have been regularly measured in Canadian, Finnish and Scandinavian power grids and pipelines since the 1970s. GIC of tens to hundreds of amperes have been recorded. GIC have also been recorded at mid-latitudes during major storms. There may even be a risk to low latitude areas, especially during a storm commencing suddenly because of the high, short-period rate of change of the field that occurs on the day side of the Earth.
GIC were first observed on the emerging electric telegraph network in 1847 during solar cycle. Technological change and the growth of conducting networks have made the significance of GIC greater in modern society. The technical considerations for undersea cables, telephone and telegraph networks and railways are similar. Fewer problems have been reported in the open literature, about these systems. This suggests that the hazard is less today, or that there are reliable methods of equipment protection.
Modern electric power transmission systems consist of generating plants inter-connected by electrical circuits that operate at fixed transmission voltages controlled at substations. The grid voltages employed are largely dependent on the path length between these substations and 200-700 kV system voltages are common. There is a trend towards higher voltages and lower line resistances to reduce transmission losses over longer and longer path lengths. Low line resistances produce a situation favorable to the flow of GIC. Power transformers have a magnetic circuit that is disrupted by the quasi-DC GIC: the field produced by the GIC offsets the operating point of the magnetic circuit and the transformer may go into half-cycle saturation. This produces harmonics to the AC waveform, localized heating and leads to high reactive power demands, inefficient power transmission and possible mis-operation of protective measures. Balancing the network in such situations requires significant additional reactive power capacity. The magnitude of GIC that will cause significant problems to transformers varies with transformer type. Modern industry practice is to specify GIC tolerance levels on new transformers.
On 13 March 1989, a severe geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protective relays tripped in a cascading sequence of events. Six million people were left without power for nine hours, with significant economic loss. Since 1989, power companies in North America, the United Kingdom, Northern Europe, and elsewhere have invested in evaluating the GIC risk and in developing mitigation strategies.
GIC risk can, to some extent, be reduced by capacitor blocking systems, maintenance schedule changes, additional on-demand generating capacity, and ultimately, load shedding. These options are expensive and sometimes impractical. The continued growth of high voltage power networks results in higher risk. This is partly due to the increase in the interconnectedness at higher voltages, connections in terms of power transmission to grids in the auroral zone, and grids operating closer to capacity than in the past.
To understand the flow of GIC in power grids and to advice on GIC risk, analysis of the quasi-DC properties of the grid is necessary. This must be coupled with a geophysical model of the Earth that provides the driving surface electric field, determined by combining time-varying ionospheric source fields and a conductivity model of the Earth. Such analyses have been performed for North America, the UK and in Northern Europe. The complexity of power grids, the source ionospheric current systems and the 3D ground conductivity make an accurate analysis difficult. By being able to analyze major storms and their consequences we can build a picture of the weak spots in a transmission system and run hypothetical event scenarios.
Grid management is also aided by space weather forecasts of major geomagnetic storms. This allows for mitigation strategies to be implemented. Solar observations provide a one- to three-day warning of an earthbound coronal mass ejection (CME), depending on CME speed. Following this, detection of the solar wind shock that precedes the CME in the solar wind, by spacecraft at the L1 Lagrangian point, gives a definite 20 to 60 minutes warning of a geomagnetic storm (again depending on local solar wind speed). It takes approximately two to three days after a CME launches from the Sun for a geomagnetic storm to reach Earth and to affect the Earth‘s geomagnetic field.
Major pipeline networks exist at all latitudes and many systems are on a continental scale. Pipeline networks are constructed from steel to contain high-pressure liquid or gas and have corrosion resistant coatings. Damage to the pipeline coating can result in the steel being exposed to the soil or water possibly causing localized corrosion. If the pipeline is buried, cathodic protection is used to minimize corrosion by maintaining the steel at a negative potential with respect to the ground. The operating potential is determined from the electro-chemical properties of the soil and Earth in the vicinity of the pipeline. The GIC hazard to pipelines is that GIC cause swings in the pipe-to-soil potential, increasing the rate of corrosion during major geomagnetic storms (Gummow, 2002). GIC risk is not a risk of catastrophic failure, but a reduced service life of the pipeline.
Pipeline networks are modeled in a similar manner to power grids, for example through distributed source transmission line models that provide the pipe-to-soil potential at any point along the pipe (Boteler, 1997; Pulkkinen et al., 2001). These models need to consider complicated pipeline topologies, including bends and branches, as well as electrical insulators (or flanges) that electrically isolate different sections. From a detailed knowledge of the pipeline response to GIC, pipeline engineers can understand the behavior of the cathodic protection system even during a geomagnetic storm, when pipeline surveying and maintenance may be suspended.
3.1.2 Cosmic-particle flux
Direct bombardment by high-energy charged particles and radiation coming from solar, stellar, and cosmic sources, act generally to form geomagnetically induced currents. For planetary bodies with no atmosphere, this flux of cosmic particles creates telluric currents directly.
Cosmic rays have sufficient energy to alter the states of circuit components in electronic integrated circuits, causing transient errors to occur (such as corrupted data in electronic memory devices or incorrect performance of CPUs) often referred to as “soft errors.” This has been a problem in electronics at extremely high-altitude, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well. Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month. To alleviate this problem, the Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event.
In 2008, data corruption in a flight control system caused an Airbus A330 airliner to twice plunge hundreds of feet, resulting in injuries to multiple passengers and crew members. Cosmic rays were investigated among other possible causes of the data corruption, but were ultimately ruled out as being very unlikely.
A high-profile recall in 2009–2010 involving Toyota vehicles with throttles that became stuck in the open position may have been caused by cosmic rays. The connection was discussed on the “Bit Flip” episode of the podcast Radiolab.
Galactic cosmic rays are one of the most important barriers standing in the way of plans for interplanetary travel by crewed spacecraft. Cosmic rays also pose a threat to electronics placed aboard outgoing probes. In 2010, a malfunction aboard the Voyager 2 space probe was credited to a single flipped bit, probably caused by a cosmic ray. Strategies such as physical or magnetic shielding for spacecraft have been considered in order to minimize the damage to electronics and human beings caused by cosmic rays.
Comparison of radiation doses, including the amount detected on the trip from Earth to Mars by the RAD on the MSL (2011–2013).
Flying 12 kilometres (39,000 ft) high, passengers and crews of jet airliners are exposed to at least 10 times the cosmic ray dose that people at sea level receive. Aircraft flying polar routes near the geomagnetic poles are at particular risk.
Cosmic rays have been implicated in the triggering of electrical breakdown in lightning. It has been proposed that essentially all lightning is triggered through a relativistic process, “runaway breakdown”, seeded by cosmic ray secondaries. Subsequent development of the lightning discharge then occurs through “conventional breakdown” mechanisms. The potential acute and chronic health effects of space radiation, as with other ionizing radiation exposures, involve both direct damage to DNA, indirect effects due to generation of reactive oxygen species, and changes to the biochemistry of cells and tissues, which can alter gene transcription and the tissue microenvironment along with producing DNA mutations. Acute (or early radiation) effects result from high radiation doses, and these are most likely to occur after solar particle events (SPEs). Likely chronic effects of space radiation exposure include both stochastic events such as radiation carcinogenesis and deterministic degenerative tissue effects. To date, however, the only pathology associated with space radiation exposure is a higher risk for radiation cataract among the astronaut corps.
The health threat depends on the flux, energy spectrum, and nuclear composition of the radiation. The flux and energy spectrum depend on a variety of factors: short-term solar weather, long-term trends (such as an apparent increase since the 1950s, and position in the Sun’s magnetic field. These factors are incompletely understood. The Mars Radiation Environment Experiment (MARIE) was launched in 2001 in order to collect more data. Estimates are that humans unshielded in interplanetary space would receive annually roughly 400 to 900 mSv (compared to 2.4 mSv on Earth) and that a Mars mission (12 months in flight and 18 months on Mars) might expose shielded astronauts to roughly 500 to 1000 mSv. These doses approach the 1 to 4 Sv career limits advised by the National Council on Radiation Protection and Measurements (NCRP) for low Earth orbit activities in 1989, and the more recent NCRP recommendations of 0.5 to 2 Sv in 2000 based on updated information on dose to risk conversion factors. Dose limits depend on age at exposure and sex due to difference in susceptibility with age, the added risks of breast and ovarian cancers to women, and the variability of cancer risks such as lung cancer between men and women. A 2017 laboratory study on mice, estimates that the risk of developing cancer due to galactic cosmic rays (GCR) radiation exposure after a Mars mission could be two times greater than what scientists previously thought.[31][32]
The quantitative biological effects of cosmic rays are poorly known, and are the subject of ongoing research. Several experiments, both in space and on Earth, are being carried out to evaluate the exact degree of danger. Additionally, the impact of the space microgravity environment on DNA repair has in part confounded the interpretation of some results.[33] Experiments over the last 10 years have shown results both higher and lower than predicted by current quality factors used in radiation protection, indicating large uncertainties exist.
Experiments in 2007 at Brookhaven National Laboratory’s NASA Space Radiation Laboratory (NSRL) suggest that biological damage due to a given exposure is actually about half what was previously estimated: specifically, it suggested that low energy protons cause more damage than high energy ones. This was shown by the fact that slower particles have more time to interact with molecules in the body. This may be interpreted as an acceptable result for space travel as the cells affected end up with greater energy deposition and are more likely to die without proliferating into tumors. This is in contrast to the current dogma on radiation exposure to human cells which considers lower energy radiation of higher weighting factor for tumor formation. Relative biological effectiveness (RBE) depends on radiation type described by particle charge number, Z, and kinetic energy per amu, E, and varies with tumor type with limited experimental data suggesting leukemia’s having the lowest RBE, liver tumors the highest RBE, and limited or no experimental data on RBE available for cancers that dominate human cancer risks including lung, stomach, breast, and bladder cancers. Studies of Harderian gland tumors in a single strain of female mice with several heavy ions have been made, however it is not clear how well the RBE for this tumor type represents the RBE for human cancers such as lung, stomach, breast and bladder cancers nor how RBE changes with sex and genetic background.
A role for cosmic rays in climate was suggested by Edward P. Ney in 1959 and by Robert E. Dickinson in 1975. It has been postulated that cosmic rays may have been responsible for major climatic change and mass-extinction in the past. According to Adrian Mellott and Mikhail Medvedev, 62-million-year cycles in biological marine populations correlate with the motion of the Earth relative to the galactic plane and increases in exposure to cosmic rays. The researchers suggest that this and gamma ray bombardments deriving from local supernovae could have affected cancer and mutation rates, and might be linked to decisive alterations in the Earth’s climate, and to the mass-extinctions of the Ordovician.
Danish physicist Henrik Svensmark has controversially argued that because solar variation modulates the cosmic ray flux on Earth, they would consequently affect the rate of cloud formation and hence be an indirect cause of global warming. Svensmark is one of several scientists outspokenly opposed to the mainstream scientific assessment of global warming, leading to concerns that the proposition that cosmic rays are connected to global warming could be ideologically biased rather than scientifically based. Other scientists have vigorously criticized Svensmark for sloppy and inconsistent work: one example is adjustment of cloud data that understates error in lower cloud data, but not in high cloud data; another example is “incorrect handling of the physical data” resulting in graphs that do not show the correlations they claim to show. Despite Svensmark’s assertions, galactic cosmic rays have shown no statistically significant influence on changes in cloud cover, and demonstrated to have no causal relationship to changes in global temperature.
3.1.3 Planetary magnetic-field plasma
If ultraviolet and X-Ray emissions from a star encounter a magnetic field, the interactions will create plasma of energetic electrons. Such plasma is created in the Earth’s magnetosphere from solar radiation, and strikes the moon’s surface as it passes through the Earth’s magnetotail.
Plasma populations throughout the universe interact with solid bodies, gases, magnetic fields, electromagnetic radiation, magnetohydrodynamic waves, shock waves, and other plasma populations. These interactions can occur locally as well as on very large scales between objects such as galaxies, stars, and planets. They can be loosely classified into electromagnetic interactions, flow-object interactions, plasma-neutral interactions, and radiation-plasma interactions.
Magnetic field lines connecting different plasma populations act as channels for the transport of plasmas, currents, electric fields, and waves between the two environments. In this way, the two plasmas become coupled electromagnetically to one another. Examples of electromagnetic interactions include the transfer of mass, momentum, and energy between Earth’s magnetosphere and ionosphere; the outward transport of angular momentum in the Jovian magnetosphere; and the production of accretion disks around protostars.
When flowing magnetized plasma strikes a solid object, an atmosphere, or a magnetosphere, strong interactions of various types can occur. Flow-object interactions range from the simple sputtering of ions from solid surfaces (like the Moon) to the production of flux ropes around unmagnetized planets with atmospheres (like Venus), to magnetic reconnection and the resulting production of large-scale disturbances (like magnetic storms) at planets with magnetospheres.
Throughout the solar system and universe, plasmas are generally embedded in a background neutral gas with which they interact. Plasma-neutral interactions range from ion drag and “flywheel” effects in collision-dominated ionospheres; to charge-exchange reactions in the rarefied plasmas of magnetospheres and stellar winds; to dust-plasma interactions in cemetery atmospheres, interstellar molecular clouds, protoplanetary disks, planetary rings, and stellar nebulas.
Radiation-plasma interactions are important in solar and stellar atmospheres, which respond to and mediate radiation in the form of magnetohydrodynamic waves and shocks emanating from the stellar surfaces and more energetic ultraviolet and x-ray photons propagating downward from the stellar coronas. These interactions will determine, for example, how ultraviolet emissions observed from stellar atmospheres are best interpreted in terms of their vertical structure.
Finally, the interactions described here take place over tremendous ranges of temporal and spatial scales. The spatial scales are often classified in terms of micro scales (at which individual particle motions are important), mesoscales (which exhibit plasma fluid effects), and macro scales (comprising large structures such as coronal mass ejections and entire magnetospheres). Often the mesoscale and macroscale dynamics are produced by micro scale phenomena (as magnetic reconnection leads to coronal mass ejections and magnetospheric substorms), while macroscale phenomena can drive dynamics at the smaller scales (as the Kelvin-Helmholtz instability is generated by large-scale flows of plasma along a boundary layer). As discussed in the preceding chapter, it is a fundamental property of space and astrophysical plasmas that efficient communication can occur across the various spatial scales.
The coupling of different spatial domains along extended magnetic field lines can occur via field-aligned particle flows, electric fields, currents, and parallel propagating waves. At Earth, the most important manifestation of this process is the strong electromagnetic coupling that occurs between the magnetosphere and the ionosphere.
This coupling includes plasma circulation, plasma escape along field lines, field-aligned particle acceleration, and parallel (to B) currents. The current density along magnetic field lines is provided by electrons from the ionosphere (the downward currents) and the much more tenuous magnetosphere (the upward currents). Since the magnetospheric densities are low (a few per cubic centimeter at most at Earth), intense upward currents require field-aligned electric fields, which accelerate magnetospheric electrons down into the atmosphere to produce the required current and, in the process, create bright auroral forms.
The processes that drive field-aligned currents into ionospheric plasmas also generate electric fields transverse to the magnetic field, the strength and location of which are strongly influenced by the properties of the ionospheric plasma.
3.2Atmospheric phenomena.
Atmospheric Optical phenomena are caused when light from the Sun or Moon interacts with elements in the air or atmosphere, and an observer detects the light after it has interacted with those elements. Often, the light emitted by the Sun or Moon will be scattered, reflected or refracted by the elements before it reaches the observer’s eyes.
Some of these events can easily fall into other categories, such as rainbows.
Large, beautiful circles that appear around the Sun or Moon if the right conditions are present in the atmosphere. Light from the Sun and Moon can be refracted off of ice crystals at high altitudes if the crystals are present, and then detected by the eye.
Alpenglow is a phenomenon that is very similar to the Belt of Venus, and occurs just after sunset. The term was coined because the pink light that appears in the sky, opposite of the sunset, gives mountains a pinkish “glow”.
Resulting from solar particles entering Earth’s atmosphere near the north and south poles, these beautiful phenomena can typically only been seen near the arctic circles
A pink or red band that sits approximately 10 degrees above the eastern horizon right after the Sun sets in the west, or 10 degrees above the western horizon before Sun rises in the east. The pink band rests on top of a darker grey or blue band which is the Earth’s shadow.
Large rays of sunlight in the sky that appear to meet or converge at the Sun from an observer’s perspective. These rays of sunlight are actually parallel, but they appear to come together due to the long distances between the observer, the horizon and the Sun.
An almost mythical phenomena that results when green in the light spectrum is refracted in the atmosphere as the Sun sets or rises. It lasts only seconds, and those who see it are said to be lucky.
Zodiacal light is a faint light reflected off of planets, dust and asteroid in our solar system. As these objects all lie on the same, flat plane (the ecliptic plane), the light reflected off of them can be seen under special circumstances. This phenomenon is similar to the way dust and stars in the Milky Way create a beautiful band across a dark, nighttime sky.
Traveling ionospheric disturbances
Atmospheric compression (i.e. acoustic waves) from a sudden event, such as an earthquake, tsunami, volcanic eruption, severe weather or rocket launches can create traveling ionospheric disturbances and this can induce telluric currents in the ground via the geomagnetic field. Travelling ionospheric disturbance are themselves a category of geomagnetically induced currents.
When a solar flare occurs on the Sun a blast of intense ultraviolet (UV) and x-ray (sometimes even gamma ray) radiation hits the dayside of the Earth after a propagation time of about 8 minutes. This high energy radiation is absorbed by atmospheric particles, raising them to excited states and knocking electrons free in the process of photoionization. The low altitude ionospheric layers (D region and E region) immediately increase in density over the entire dayside. The ionospheric disturbance enhances VLF radio propagation. Scientists on the ground can use this enhancement to detect solar flares; by monitoring the signal strength of a distant VLF transmitter, sudden ionospheric disturbances (SIDs) are recorded and indicate when solar flares have taken place. The small geomagnetic effect in the lower ionosphere appears as a small hook on magnetic records and is therefore called “geomagnetic crochet effect” or “sudden field effect”.
Short wave radio waves (in the HF range) are absorbed by the increased particles in the low altitude ionosphere causing a complete blackout of radio communications. This is called a short wave fadeout (SWF). These fadeouts last for a few minutes to a few hours and are most severe in the equatorial regions where the Sun is most directly overhead. The ionospheric disturbance enhances long wave (VLF) radio propagation. SIDs are observed and recorded by monitoring the signal strength of a distant VLF transmitter. A whole array of sub-classes of SIDs exist, detectable by different techniques at various wavelengths: the short-wave fadeout (SWF), the SPA (Sudden Phase Anomaly), SFD (Sudden Frequency Deviation), SCNA (Sudden Cosmic Noise Absorption), SEA (Sudden Enhancement of Atmospherics), etc. Following the suggestion by Ogawa, (Kumazawa et al.2000), an electromagnetic method was developed for ACROSS (EM-ACROSS). The propagation of an electromagnetic disturbance into the earth’s crust is mostly dependent on the electrical conductivity of the ground. The electrical conductivity is expected to depend on the H2O content and the physicochemical state of the crust. Kasahara et al. (2001) discussed the relationship of free water, hydrous minerals, and the seismic characteristics in three typical subduction zones, and suggested the possibility that earthquake occurrence is controlled by differences in the free-water content of the rocks and hydrous minerals along subduction zone boundaries. If H2O is sufficiently abundant in the seismogenic zone to be a factor in earthquake generation, it could be detected as an electrical conductivity anomaly. In order to investigate the presence of water and any change in the physicochemical state due to H2O flow, continuous monitoring using electromagnetic fields is important. Most electromagnetic methods utilize natural disturbances such as magnetic storms, because natural signals are much larger than the signals that can be generated from artificial electromagnetic sources. However, natural disturbances are irregular and their incident direction and signal form are usually unknown. They are not suitable for continuous monitoring.
Therefore, for accurate monitoring, it is essential to use an artificial signal. EM-ACROSS uses a time base synchronized to a GPS clock similar to the seismic ACROSS (Kunitomo, et al., 2004), to obtain signal enhancement by stacking. The transfer function obtained for the electromagnetic field propagated from the source dipole to the receiver is essentially a Green’s function.
When an electromagnetic wave travels through an electrified medium, the electrons are set in motion and the wavelets re-radiated from these electrons modify the phase and amplitude of the advancing wave. Consider an ionized medium with a constant externally applied magnetic field, which has the following assumed properties:
Positive and negative charges are equal in magnitude and uniformly distributed in space.
The medium does not change rapidly in time or space, and therefore can be considered homogeneous in the neibour hood of a particular point.
Ions are much heavier than electrons and can be assumed stationary ton the passage of high frequency radio waves.
The thermal motions of electrons are unimportant (cold plasma approximation)
The magnetic permeability is the same as that of freed space.
A common source of EM radiation is a transmitting antenna (as opposed to a receiving antenna, like those attached to a radio or television receiver). Alternating current in the antenna is driven by a sinusoidal ac circuit. As the oscillating charges accelerate during their back-and-forth motion in the antenna, electric and magnetic fields are created in a complicated geometry in the space around the antenna. The changing electric field produces a changing magnetic field, which in turn produces a changing electric field, and so on. In this way, an EM wave propagates away from the antenna. Near the antenna the electric and magnetic fields are quite complex and need not be considered here. But for the simple antenna (called a dipole antenna), at a distance far from the antenna along a line perpendicular to the antenna, the fields form a relatively simple pattern called a p. In a plane EM wave, the electric field E and the magnetic field B are, at any instant, constant in each plane perpendicular to the direction of propagation of the wave.
Seismic Electric Signals
Seismic Electric Signals (SES) [1,2,3,4] are low frequency (≤1 Hz) transient changes of the electric field of the Earth that have been found to precede major earthquakes with lead times ranging from several hours to a few months [5,6]. They are emitted when the gradually increasing stress before an earthquake reaches a critical value [7], in which the electric dipoles formed due to point defects [8,9] in the future focal area exhibit cooperative orientation, thus resulting in an emission of a transient electric signal. SES can consist of a single pulse or a series of pulses. The latter are referred to as SES activities.
In Greece, practically, the potential difference ΔV is measured between two electrodes Pb/PbCl2 placed 2 m [10] deep into the earth and which form a measuring dipole. There are two types of dipoles: the short dipoles with length L 50–400 m and the long dipoles with length 2–20 km [10]. At least four short dipoles should be installed perpendicular to each other in the directions east–west (EW) and north–south (NS) while there should not be any common electrodes. The places where the long dipoles are installed are selected to allow distinguishing the SES from nearby man-made noise sources.
Electric variations can be considered as SES if they satisfy the following four criteria simultaneously.
They appear selectively at some of the stations that constitute a recording network and simultaneously at the long and short dipoles of the recording station. The ratio ΔVL is constant for the short dipoles oriented in the same direction.
The criterion ΔVL≈const must hold for a long and short dipole placed parallel to each other. That means that both the short and long dipoles record approximately the same mean value of the electric field.
ATC are either possible precursory electric currents flowing inside the earth or artificial noise originating from man-made sources. These can be distinguished by the aforementioned four criteria or by employing natural time analysis. For SES activities, the entropy S in natural time χ defined as the derivative with respect to q of the fluctuation function ⟨χq⟩−⟨χ⟩q at q=1, which results in: S≡⟨χlnχ⟩−⟨χ⟩ln⟨χ⟩, as well as the entropy S− which results when we employ time-reversal are both smaller than the entropy Su of the uniform distribution in natural time (see Ref. [17]). Notably, it has been recently shown in natural time that an SES activity initiates when the fluctuations of the order parameter of seismicity minimize [18] and in addition the change of the entropy of seismicity under time reversal exhibits a precursory minimum [19] with a lead time comparable to that of an SES activity. In other words, the entropy of seismicity in natural time exhibits a precursory behavior closely associated with the appearance of the SES.
According to the review article by Uyeda and coworkers [20], the earthquake prediction method based on SES, which is called VAN (VAN comes from the initials of Varotsos, Alexopoulos and Nomikos) method [21], has been a target of a heated debate. As far as Uyeda and coworkers have critically examined, VAN successes are convincing and show in their Figure 4 are the score of VAN predictions for the period 1985–2003. They also state that public impact of VAN’s predictions has been large because lives have actually been saved at some disastrous earthquakes.
Lightning strikes
Electrical charge is transferred between the ground and the atmosphere during lightning strikes and the tops of storm clouds close an electrical circuit with the ionosphere. Lightning discharge is energetic and creates plasma that we see.
Telephones, modems, computers and other electronic devices can be damaged by lightning, as harmful overcurrent can reach them through the phone jack, Ethernet cable, or electricity outlet. Close strikes can also generate electromagnetic pulses (EMPs) – especially during “positive” lightning discharges.
Lightning currents have a very fast rise time, on the order of 40 kA per microsecond. Hence, conductors of such currents exhibit marked skin effect, causing most of the currents to flow through the outer surface of the conductor.
In addition to electrical wiring damage, the other types of possible damage to consider include structural, fire, and property damage.
The field of lightning protection systems is an enormous industry worldwide due to the impacts lightning can have on the constructs and activities of humankind. Lightning, as varied in properties measured across orders of magnitude as it is, can cause direct effects or have secondary impacts; lead to the complete destruction of a facility or process or simply cause the failure of a remote electronic sensor; it can result in outdoor activities being halted for safety concerns to employees as a thunderstorm nears an area and until it has sufficiently passed; it can ignite volatile commodities stored in large quantities or interfere with the normal operation of a piece of equipment at critical periods of time.
Most lightning protection devices and systems protect physical structures on the earth, aircraft in flight being the notable exception. While some attention has been paid to attempting to control lightning in the atmosphere, all attempts proved extremely limited in success. Chaff and silver iodide crystal concepts were devised to deal directly with the cloud cells and were dispensed directly into the clouds from an overflying aircraft. The chaff was devised to deal with the electrical manifestations of the storm from within, while the silver iodide salting technique was devised to deal with the mechanical forces of the storm.
Hundreds of devices, including lightning rods and charge transfer systems, are used to mitigate lightning damage and influence the path of a lightning flash.
A lightning rod (or lightning protector) is a metal strip or rod connected to earth through conductors and a grounding system, used to provide a preferred pathway to ground if lightning terminates on a structure. The class of these products are often called a “finial” or “air terminal”. A lightning rod or “Franklin rod” in honor of its famous inventor, Benjamin Franklin, is simply a metal rod, and without being connected to the lightning protection system, as was sometimes the case in the old days, will provide no added protection to a structure. Other names include “lightning conductor”, “arrester”, and “discharger”; however, over the years these names have been incorporated into other products or industries with a stake in lightning protection. Lightning arrester, for example, often refers to fused links that explode when a strike occurs to a high voltage overhead power line to protect the more expensive transformers down the line by opening the circuit. In reality, it was an early form of a heavy duty surge protection device (SPD). Modern arresters, constructed with metal oxides, are capable of safely shunting abnormally high voltage surges to ground while preventing normal system voltages from being shorted to ground.
Lightning is like a current along a wire, inducing a magnetic field, which interacts with telluric currents deep in the subsurface. These telluric currents have more impact on lightning strike locations than vegetation, infrastructure, or topography. There is extensive professional literature on magnetotellurics, ElectroSeis, Tipper and other geophysical exploration techniques based on passive measurements of lightning induced current
Lightning strikes are understood to have a skin depth of a few meters. We know lightning strikes are a major source for charging telluric currents, all the way to the Mohorovičić discontinuity, at the base of the crust at a depth of 10-90 km (6-55 miles), and everything below the Moho is believed to be molten, and therefore a good conductor. Lightning storms build up over hours, lightning strikes over milliseconds, and this build-up of static electricity in the atmosphere is what charges telluric currents, and what interacts with these currents to guide lightning strike locations.
Geophysicists have known atmospheric static currents charge telluric currents since the 1950s, with the invention of magnetotellurics as a geophysical exploration technique. The build-up to a lightning strike takes up to 500 ms and can be derived by summing the time for related Cloud-to-Cloud (C2C) and Cloud-to-Ground (C2G) strikes. This build-up of atmospheric charge identifies an area of opposite charge in the subsurface of the earth. Lightning stroke pathways are largely determined by the field lines connecting these two ‘capacitor plates’.
Treating the atmosphere and the earth as a capacitor, the charged thunder cloud can be considered one plate, while the other is the earth underlying the charged cloud. The dielectric is the insulating medium between the capacitor plates that transmits electrical force without conduction; namely the air and the earth, between the atmospheric static charge build-up and the interacting and oppositely charged currents in a different part of the thunderclouds (C2C strokes) or telluric currents at depth (C2G strokes). Dynamic makes two assumptions: firstly, lightning occurs when there is sufficient charge to bridge the capacitor; and secondly, lightning is affected by geology to a depth proportional to the cloud height, as estimated from the Peak Current of the stroke. We recognize it is hard to accurately measure the height of a lightning stroke, and that the lightning strike itself, lasting microseconds, is a small part of the electrical interaction between the atmosphere and the lithosphere. The bottom line is lightning is a meteorological event most often associated with storm clouds. Lightning seldom occurs in the extreme northern and southern latitudes, over deep water, or in some deserts, meaning there will be less lightning data in these areas for lightning analysis.
The North American Lightning Detection Network, containing 20 years of data from the US and Canada, is the most extensive lightning database available, with records of location, time, Peak Current, Peak-to-Zero Time, recording quality, and other attributes. Most strikes in the US are recorded by 10–25 sensors, each within about 1,000 km of the strike location. These data are collected and stored for insurance, safety, and meteorological reasons, but Dynamic Measurement’s exclusive data license for natural resource exploration highlights new uses for them.
Whistler induction
Lightning discharge heats the air and creates plasma. The entire lightning channel radiates electromagnetic energy. If in the radio frequency, it is called a radio atmospheric signal. If the plasma from lightning discharge travels along geomagnetic lines, the resulting radio-frequency disturbances are termed “whistlers” and are named for the sound which this interference makes in telephone lines.
The induction energy is the energy resulting from the distortion of one molecule by the mean electric field due to the other molecules. Like the electrostatic energy, it is absent in the case of inert gas atoms. The main contribution to the induction energy is due to the electric dipole induced in the Coupling of Lightning Discharges to Transmission (and/or Power) Lines
The problem of the coupling of external electromagnetic waves (such as lightning discharges and geomagnetic disturbances) to transmission (and/or power) lines, is of fundamental importance in the field of electromagnetic compatibility (EMC). Direct coupling of lightning to transmission/power lines has been widely and extensively studied, but little study has been done on the induction of power transmission lines when a lightning discharge ith molecule by the field resulting from the charge distribution of the other molecules.
Atmospheric Optical phenomena are caused when light from the Sun or Moon interacts with elements in the air or atmosphere, and an observer detects the light after it has interacted with those elements. Often, the light emitted by the Sun or Moon will be scattered, reflected or refracted by the elements before it reaches the observer’s eyes.
Some of these events can easily fall into other categories, such as rainbows.
Large, beautiful circles that appear around the Sun or Moon if the right conditions are present in the atmosphere. Light from the Sun and Moon can be refracted off of ice crystals at high altitudes if the crystals are present, and then detected by the eye.
Alpenglow is a phenomenon that is very similar to the Belt of Venus, and occurs just after sunset. The term was coined because the pink light that appears in the sky, opposite of the sunset, gives mountains a pinkish “glow”.
Resulting from solar particles entering Earth’s atmosphere near the north and south poles, these beautiful phenomena can typically only been seen near the arctic circles.
A pink or red band that sits approximately 10 degrees above the eastern horizon right after the Sun sets in the west, or 10 degrees above the western horizon before Sun rises in the east. The pink band rests on top of a darker grey or blue band which is the Earth’s shadow.
Large rays of sunlight in the sky that appear to meet or converge at the Sun from an observer’s perspective. These rays of sunlight are actually parallel, but they appear to come together due to the long distances between the observer, the horizon and the Sun.
An almost mythical phenomena that results when green in the light spectrum is refracted in the atmosphere as the Sun sets or rises. It lasts only seconds, and those who see it are said to be lucky.
Zodiacal light is a faint light reflected off of planets, dust and asteroid in our solar system. As these objects all lie on the same, flat plane (the ecliptic plane), the light reflected off of them can be seen under special circumstances. This phenomenon is similar to the way dust and stars in the Milky Way create a beautiful band across a dark, nighttime sky.
Atmospheric Optical phenomena are caused when light from the Sun or Moon interacts with elements in the air or atmosphere, and an observer detects the light after it has interacted with those elements. Often, the light emitted by the Sun or Moon will be scattered, reflected or refracted by the elements before it reaches the observer’s eyes.
Some of these events can easily fall into other categories, such as rainbows.
Large, beautiful circles that appear around the Sun or Moon if the right conditions are present in the atmosphere. Light from the Sun and Moon can be refracted off of ice crystals at high altitudes if the crystals are present, and then detected by the eye.
Alpenglow is a phenomenon that is very similar to the Belt of Venus, and occurs just after sunset. The term was coined because the pink light that appears in the sky, opposite of the sunset, gives mountains a pinkish “glow”.
Resulting from solar particles entering Earth’s atmosphere near the north and south poles, these beautiful phenomena can typically only been seen near the arctic circles.
A pink or red band that sits approximately 10 degrees above the eastern horizon right after the Sun sets in the west, or 10 degrees above the western horizon before Sun rises in the east. The pink band rests on top of a darker grey or blue band which is the Earth’s shadow.
Large rays of sunlight in the sky that appear to meet or converge at the Sun from an observer’s perspective. These rays of sunlight are actually parallel, but they appear to come together due to the long distances between the observer, the horizon and the Sun.
An almost mythical phenomena that results when green in the light spectrum is refracted in the atmosphere as the Sun sets or rises. It lasts only seconds, and those who see it are said to be lucky.
Zodiacal light is a faint light reflected off of planets, dust and asteroid in our solar system. As these objects all lie on the same, flat plane (the ecliptic plane), the light reflected off of them can be seen under special circumstances. This phenomenon is similar to the way dust and stars in the Milky Way create a beautiful band across a dark, nighttime sky
3.3. Oceanic phenomena
The oceans on Earth can be calming, beautiful or deceptively powerful. The same can be said about the phenomena that occur within them. Tsunamis are destructive forces that wield tremendous power, while smaller, regular waves are some of the most beautiful sights on Earth.
Oceanic phenomena can be defined as naturally occurring events that are contained within or directly caused by oceans. Below are some of the discussed oceanic phenomena:
Huge concentrations of algae that form in warmer ocean waters, as well as lakes and rivers. These growths can be toxic to humans and marine life, and have devastating impacts on tourism and fisheries.
Icicles of death- these are fragile crystal structures found near the bottom of the ocean. They are capable of killing starfish and other slow moving creatures at the bottom of the sea.
Tsunamis occur as a result of water displacement caused by large earthquakes or volcanic eruptions beneath the ocean floor. They are stealthy and difficult in deep ocean waters, but can cause tremendous damage when they arrive at shore.
Forming at high altitudes in massive Cumulonimbus clouds, hail can grow as big as 8 inches or more and fall at velocities over 100 miles per hour. It has the potential to cause damage to vehicles and more.
There are three sources of oceanic telluric currents, such as the induction of the space current system, the periodic variation of the tidal response/oceanic current potential and the circulation component of deep earth currents. The oceanic telluric current originates from the induction of the disturbance of the space current system in the earth medium and has different responses at different latitudes (longitudes) on the earth. In recent years, the observations of space-to-earth have further contributed to the development of deep ocean current at the global scale. (William 2005).
Moreover, deep conductivity information is detected by the magnetotelluric method, and the water content in the upper mantle is estimated by petrological experiments and heat flow structure detection (Zhang et al. 2012), which may provide the evidence that deep currents can affect near-surface telluric currents. The basic characteristic of the telluric current is that the current path tends to be a good conductive medium, and the energy flow concentrates in this good conductor. Moreover, GIC is an important source that may cause negative effects even disasters by man-made noise such as power grid, pipelines and railways, which is faster part of the current source if power networks contact to land (Liu et al. 2016, 2017). Therefore, the direction of long-period telluric current vector reflects the electrical inhomogeneity of deep medium, which is a key to understand the differentiation of deep conductivity.
The gravitational effect of the moon on the oceans causes ocean waves. The position of the moon around the Earth also directly affects when high or low tides occur.
Electrochemical effects in the ocean
In the oceans, different layers of water will be stratified by temperature and salinity, and each influences density. Both of these gradients influence electrical conductivity, and create variations in electric currents in the oceans.
The geoelectric field arises from the existence of telluric currents flowing in the solid earth medium. In recent decades, global observations have suggested that the telluric current is as active as the geomagnetic-inducted current (GIC) (Medford et al. 1981), especially within 10–200 s periods, possibly because the induced current adds to the primary horizontal components rather than subtracts from the vertical components (Jones et al. 1969). The shorter- and longer-period groups are related to the ionospheric current system and the induction phenomena inside the earth, respectively. As discussed by Chave et al. (1992) and Berguig et al. (2013), the telluric current generated from the following several sources: one is fluctuations of the geomagnetic field at the earth’s surface caused by time-varying electric current systems in the ionosphere and magnetosphere; the other is dynamo processes within the earth’s core and the motional induction caused by the flow of conducting seawater across the earth’s geomagnetic field. The significance of these sources depends on the frequency and spatial scale of the source. The stray current that can arise from motional induction, have become more recognized in recent years, another possible source of systematic errors of telluric current is potential measurements.
Correspondingly, there are three sources of oceanic telluric currents, such as the induction of the space current system, the periodic variation of the tidal response/oceanic current potential and the circulation component of deep earth currents. According to Serson (1973) and William (2005), the oceanic telluric current originates from the induction of the disturbance of the space current system in the earth medium and has different responses at different latitudes (longitudes) on the earth. In recent years, the observations of space-to-earth have further contributed to the development of deep ocean current at the global scale (Schnepf et al. 2014, 2015). In addition, deep conductivity information is detected by the magnetotelluric method, and the water content in the upper mantle is estimated by petrological experiments and heat flow structure detection (Yoshino et al. 2008; Zhang et al. 2012), which may provide the evidence that deep currents can affect near-surface telluric currents. The basic characteristic of the telluric current is that the current path tends to be a good conductive medium, and the energy flow concentrates in this good conductor. Moreover, GIC is an important source that may cause negative effects even disasters by man-made noise such as power grid, pipelines and railways, which is faster part of the current source if power networks contact to land (Liu et al. 2016, 2017). Therefore, the direction of long-period telluric current vector reflects the electrical inhomogeneity of deep medium (Zhang et al. 2017), which is a key to understand the differentiation of deep conductivity.
The electromagnetic field observations on the earth’s surface can reflect the information of the earth’s deep conductor structure and provide a direct record of the electromagnetic disturbance outside the solid earth. The observation data can be used to study the deep earth’s electromagnetic dynamics, especially the crust–mantle activity, and also a basis for studying the energy exchange between the earth and space.
Studies on telluric current in the zone between land and sea are limited. Generally speaking, the current superimposed on any DC currents are induced by other processes in the geophysical environment, such as ocean tides (Lanzerotti et al. 1985). This may affect the deposition of heavy metal ions in still water and the stability of coastal power grids and coastal high-speed railway traction grids under geomagnetic storms, even it can destroy the cathodic protection for submarine pipelines and the steel frames of drilling platforms (Thomson et al. 2005; Degiorgi and Wimmer 2005; Liu et al. 2010, 2011, 2016).
Deep‐sea hydrothermal vents are hot springs on the seafloor. In recent years, electricity generation in deep‐sea hydrothermal vents has been reported. Electricity can be generated through the sulfide minerals that form in seafloor hydrothermal deposits, and these minerals can convert the redox and heat energy between hydrothermal fluids and seawater into electric power. The physical and chemical phenomena of generating electricity from natural minerals provide key insights into development of deep‐sea power plants and novel electricity‐conversion materials with earth abundant elements. In addition, the new findings have established a novel concept of life, e. g., existence of electricity‐sustained life in hydrothermal vents and widespread occurrence of electron‐uptake ecosystems on the seafloor, together with a new hypothesis about the origin of life
Since the discovery in late 1970s, deep‐sea hydrothermal vents have attracted great interests from various fields of science e. g., the occurrence and distribution of unique ecosystems, the relevance to origin and early evolution of life in the Earth, the formation of hydrothermal mineral deposits, the impacts on the global ocean chemistry and plate tectonics, and the ubiquity in extraterrestrial planets.1 Recently, researchers have found the electricity generation phenomenon in deep‐sea hydrothermal systems by analyzing the electric properties of mineral samples collected from deep‐sea hydrothermal vents and performing in‐situ electrochemical measurements in the deep sea.2 In this article, we briefly review the history and process of discovering electricity generation in the deep sea and introduce new studies inspired by this phenomenon.
Deep‐sea Hydrothermal Vents
Deep‐sea hydrothermal vents are fractures in the Earth’s crust that discharge crustal heated fluids. The hydrothermal fluid circulation is geologically associated with magmatism and geochemically processed by high‐temperature mineral‐seawater interactions. The fluids contain abundant metallic ions and gases and form mineral deposits when cooled by the surrounding, cold seawater on the seafloor.
Unique ecosystems are found around hydrothermal vents, including high densities of tubeworms, shrimps, crabs, snails, clams, and other macro‐ and micro‐organisms. Although photosynthetic organisms, such as plants using light energy, are the primary producers and sustain the surface ecosystems, the deep‐sea vent ecosystems are based on the redox energy between the reductive hydrothermal fluid and oxidative seawater. Various microorganisms can use the redox energy to produce organic matter from inorganic carbon, and these organisms are called chemosynthetic or chemoautotrophic microorganisms. Many animals host specific chemosynthetic microorganisms inside and outside of their cells and tissues, and utilize organic matter via the symbionts as the nutrition source. Therefore, the biomass production and maintenance depend on the redox non‐equilibrium conditions in the mixing zones of reductive hydrothermal fluid and oxidative seawater.
Hydrothermal vents act as natural plumbing systems that transport heat and chemicals from the interior of the Earth and that help regulate global ocean chemistry. In the process, they accumulate vast amounts of potentially valuable minerals on the seafloor.
For instance, the mammoth copper mines of Cyprus, were formed by hydrothermal activity millions of years ago before those rocks were uplifted from the seafloor to become dry land. The difficulty of mining in deep water near fragile ecosystems and the relatively small size of ocean bottom deposits compared to those on land have so far prevented seafloor mining from becoming commercially viable.
Vents also support complex ecosystems of exotic organisms that have developed unique biochemical adaptations to high temperatures and environmental conditions we would consider toxic. Learning about these organisms can teach us about the evolution of life on Earth and the possibility of life elsewhere in the solar system and the universe. Many previously unknown metabolic processes and compounds found in vent organisms could also have commercial uses one day.
The fluid from the hydrothermal vents contains gases that are in liquid form because of the high pressure of the deep ocean. In the past, bringing such samples to the surface resulted in loss of the gaseous portion. WHOI scientists and engineers developed the IGTS to keep samples of vent fluid at high pressure until they can be brought to a lab for analysis. WHOI geologist Chris German led the expedition, which visited the deepest known hydrothermal vents in the world.
Electricity Generation in Deep‐sea Hydrothermal Fields
Electrochemical Properties of Sulfide Minerals from Deep‐sea Vent
In the process of upwelling through the subsea floor and discharging from the seafloor vents, metal‐ and sulfide‐rich hydrothermal fluids are cooled and mixed with seawater near the seafloor, resulting in mineral precipitation and formation of seafloor and subsea floor hydrothermal mineral deposits such as chimneys, flanges and mounds. Hydrothermal mineral deposits have been extensively studied as potential, valuable metal resources. In addition, sulfide metals are expected to serve as novel materials for catalysts, sensor elements, and other applications. However, little information is available on the electrical properties of natural hydrothermal minerals. (Nakamura et al. 2000) examined the electric conductivity characteristics of natural minerals, collected from a black smoker vent chimney in a deep‐sea hydrothermal field in southern Lau Basin.
The current−voltage characteristics of mineral were examined over a 2‐mm distance using specimens cut from the inner surface, middle inside, and outer surface of the chimney wall. The observed linear increase in the current with the voltage verified the metal‐like electrical conduction of the chimney specimens. In addition, long‐distance conductivity measured at various locations between the inner and outer surface of the chimney wall and a chimney block can be used as a cable for an electric circuit. Bulk chalcopyrite and pyrite crystals are typically considered non‐conductors. The chimney sulfide minerals were comprised of micron and submicron crystalline particles that formed a densely interconnected structure. Together with the formation of structural defects, the sulfide chimney minerals are capable of mediating efficient electron transport.
Metabolic electrochemistry in the ocean
The metabolic action of micro- and macrobiota in the oceans may contribute to an electrical signal that is measurable.
Climate change with increasing temperature and ocean acidification (OA) poses risks for marine ecosystems. According to Pörtner and Farrell, synergistic effects of elevated temperature and CO₂-induced OA on energy metabolism will narrow the thermal tolerance window of marine ectothermal animals. To test this hypothesis, we investigated the effect of an acute temperature rise on energy metabolism of the oyster, Crassostrea gigas chronically exposed to elevated CO₂ levels (partial pressure of CO₂ in the seawater ~0.15 kPa, seawater pH ~ 7.7). Within one month of incubation at elevated PCo₂ and 15 °C hemolymph pH fell (pH(e) = 7.1 ± 0.2 (CO₂-group) vs. 7.6 ± 0.1 (control)) and P(e)CO₂ values in hemolymph increased (0.5 ± 0.2 kPa (CO₂-group) vs. 0.2 ± 0.04 kPa (control)). Slightly but significantly elevated bicarbonate concentrations in the hemolymph of CO₂-incubated oysters ([HCO₃⁻](e) = 1.8 ± 0.3 mM (CO₂-group) vs. 1.3 ± 0.1 mM (control)) indicate only minimal regulation of extracellular acid-base status. At the acclimation temperature of 15 °C the OA-induced decrease in pH (e) did not lead to metabolic depression in oysters as standard metabolism rates (SMR) of CO₂-exposed oysters were similar to controls. Upon acute warming SMR rose in both groups, but displayed a stronger increase in the CO₂-incubated group. Investigation in isolated gill cells revealed a similar temperature dependence of respiration between groups. Furthermore, the fraction of cellular energy demand for ion regulation via Na+/K+-ATPase was not affected by chronic hypercapnia or temperature. Metabolic profiling using ¹H-NMR spectroscopy revealed substantial changes in some tissues following OA exposure at 15 °C. In mantle tissue alanine and ATP levels decreased significantly whereas an increase in succinate levels was observed in gill tissue. These findings suggest shifts in metabolic pathways following OA-exposure. Our study confirms that OA affects energy Water can be converted to its component elemental gasses, H2 and O2 through the application of an external voltage. Water doesn’t decompose into hydrogen and oxygen spontaneously as the Gibbs free energy for the process at standard conditions is about 474.4 kJ. The decomposition of water into hydrogen and oxygen can be performed in an electrolytic cell. In it, a pair of inert electrodes usually made of platinum immersed in water act as anode and cathode in the electrolytic process. The electrolysis starts with the application of an external voltage between the electrodes. This process will not occur except at extremely high voltages without an electrolyte such as sodium chloride or sulfuric acid (most used 0.1 M).
Bubbles from the gases will be seen near both electrodes. The following half reactions describe the process mentioned above:
Anode (oxidation): 2 H2O(l) → O2(g) + 4 H+(aq) + 4 e−
Cathode (reduction): 2 H2O(g) + 2 e− → H2(g) + 2 OH−(aq)
Overall reaction: 2 H2O(l) → 2 H2(g) + O2(g)
Although strong acids may be used in the apparatus, the reaction will not net consume the acid. While this reaction will work at any conductive electrode at a sufficiently large potential, platinum catalyzes both hydrogen and oxygen formation, allowing for relatively mild voltages (~2 V depending on the pH) metabolism in oysters and suggests that climate change may affect populations of sessile coastal invertebrates such as mollusks.
Surface phenomena
This is the thin layer of a substance at the boundary of contiguous bodies, mediums or phases. These properties result from excess free energy of the surface layer and from the special features of the layer’s structure and composition. It may be either with chemical transformation or purely physical in nature; they occur at liquid and solid interface boundaries. Capillary phenomena which includes capillary absorption of liquid into porous bodies, capillary condensation and establishment of the equilibrium shape of drops, gas bubbles and menisci. Capillary phenomena is related to surface tension resulting from the deformation liquid boundaries. Molecular nature and properties of a surface may be radically altered as a result of the formation of surface monomolecular layers or phase films. Such changes may result from such physical processes as adsorption, surface diffusion, and the spreading of liquids or from the chemical interaction of components of the contiguous phases. Any modification of the surface, or interphase, layer usually leads to an increase or decrease in molecular interaction between the contiguous phases.
Physical or chemical transformations in surface layers strongly affect the nature and rate of such heterogeneous phenomena as corrosive, catalytic, and membrane processes. Surface phenomena also affect the typically volumetric properties of bodies. Thus, a decrease in the free surface energy of solids by an actively adsorptive medium results in a decrease in the strength of these bodies. Such surface phenomena as electroadhesive and electrocapillary phenomena and electrode processes, which result from the presence of electric charges in the surface layer, form a special group. Physical or chemical changes in the surface layer of a conductor or semiconductor significantly affect the electron work function. They also affect such surface phenomena in semiconductors as surface states, surface conductivity, and surface recombination; these influences are reflected in the operational characteristics of such semiconductor instruments as solar batteries and photodiodes.
Surface phenomena are found in any heterogeneous system consisting of two or several phases. In essence, the entire physical world, from cosmic bodies to submicroscopic formations, is heterogeneous. Only systems in limited volumes of space may be regarded as homogeneous. Thus, the role of surface phenomena in natural and technological processes is great. Surface phenomena are especially important in disperse systems, in which the interphase surface is most highly developed. In fact, the conditions facilitating the appearance and prolonged existence of such systems are related to surface phenomena.
The major problems of colloid chemistry reduce to surface phenomena in disperse systems. All the processes that lead to changes in the size of the particles of the highly dispersed phase, including coagulation, coalescence, peptization, and emulsifica-tion, are due to the interaction of Brownian motion and surface phenomena. In coarsely disperse and macroheterogeneous systems, a primary role is played by the tension between surface forces and external mechanical actions. Surface phenomena, by affecting the magnitude of the free surface energy and the structure of the surface layer, control the origin and growth of new-phase particles in supersaturated vapors, solutions, and melts. Surface phenomena also control the interaction of colloidal particles in the formation of various types of disperse structures. Surfactants, which alter the structure and properties of interphase surfaces as a result of adsorption, often fundamentally affect the extent and tendency of processes caused by surface phenomena.
The utilization of surface phenomena in industry permits the improvement of existing technological processes. Surface phenomena often determine methods for extending the durability of important structural and construction materials; they also determine the efficiency of mining and concentrating minerals and the quality and properties of products of the chemical, textile, food-processing, and pharmaceutical industries. Surface phenomena have great importance in metallurgy and in the production of ceramics, metal ceramics, and such polymer materials as plastics, rubbers, paints, and varnishes. Such surface phenomena as lubrication, abrasion, contact interaction, and structural changes in polycrystalline and composite materials, as well as electrical and electrochemical processes and phenomena occurring on the surfaces of solids, are important in technology.
A knowledge of surface phenomena in biology makes it possible to control biological processes with the aim of increasing agricultural productivity and developing the microbiological industry and the potentialities of medicine and veterinary
3.4.1 Artificial signals
Earth electric currents may come from the transmission of electricity or electromagnetic radiation emanating from human-made sources and also from on-ground activity, such as from electric trains. The magnitude of artificial telluric currents depends directly upon the generation process. Extremely low frequency radio waves are generated by heating the ionosphere, and are used by the US military to communicate with submarines.
Sudden shrieks of radio waves from deep space keep slamming into radio telescopes on Earth, spattering those instruments’ detectors with confusing data. And now, astronomers are using artificial intelligence to pinpoint the source of the shrieks, in the hope of explaining what’s sending them to Earth from researchers suspect billions of light-years across space.
Usually, these weird, unexplained signals are detected only after the fact, when astronomers notice out-of-place spikes in their data sometimes years after the incident. The signals have complex, mysterious structures, patterns of peaks and valleys in radio waves that play out in just milliseconds. That’s not the sort of signal astronomers expect to come from a simple explosion, or any other one of the standard events known to scatter spikes of electromagnetic energy across space. Astronomers call these strange signals fast radio bursts (FRBs). Ever since the first one was uncovered in 2007, using data recorded in 2001, there’s been an ongoing effort to pin down their source. But FRBs arrive at random times and places, and existing human technology and observation methods aren’t well-primed to spot these signals.
Now, in a paper published July 4 in the journal Monthly Notices of the Royal Astronomical Society, a team of astronomers wrote that they managed to detect five FRBs in real time using a single radio telescope. [The 12 Strangest Objects in the Universe]
Wael Farah, a doctoral student at Swinburne University of Technology in Melbourne, Australia, developed a machine-learning system that recognized the signatures of FRBs as they arrived at the University of Sydney’s Molonglo Radio Observatory, near Canberra. As Live Science has previously reported, many scientific instruments, including radio telescopes, produce more data per second than they can reasonably store. So they don’t record anything in the finest detail except their most interesting observations.
3.4.2 Metabolic electrochemistry in soil
The daily action of plants, fungi, bacteria, lichen or algae that inhabit soil and rock fissures may produce electrical signals from electrochemical processes related to metabolism. Some evidence exists that soil microbes respond to changes in the geomagnetic field though the converse has not been shown. Environmental metagenomics now allows us to directly measure genetic potential of microbiomes in situ with the capability of linking soil chemistry to soil biology (Vogel et al .,2010) Yet, we lack vital knowledge to link these soil microbiomes to their in situ activities. This is because community-level phenotypes of microbial consortia vary significantly due to the presence of genes, their expression, localization, and population size of microbes in various biogeochemical conditions. Complementing genetic analysis with direct biochemical observations presents an opportunity to establish direct association between genes and functions (Phelan et al., 2012). However, this requires a precise understanding of soil organic matter composition, concentration, and accessibility to microbes. Since these processes occur within the three-dimensional architecture of the soil environment, the spatial distribution of microbes and metabolites represents another important factor in linking metagenomes to soil chemistry.
So far, the understanding of soil organics has been very coarse.Soil carbon was assumed to be composed of recalcitrant macromolecules, like humic substances, formed via in situ polymerization and other processes. However, recent spectroscopic analyses have led to the emerging view that soil carbon is largely composed of small molecular weight microbial metabolites associated, with varying affinity, to soil minerals (Schmidt et al, 2011) Therefore, to decipher the underlying processes of soil chemistry, the definition of soil carbon as total organic carbon and more recently as labile and recalcitrant carbon is not enough to link soil metabolites to microbial genomics. Fortunately, soil metabolomics methods are being developed to directly characterize the small molecule metabolites within soils, enabling determination of the critical factors governing soil carbon cycling such as plant biomass deconstruction, metabolite partitioning into the microbiome, and metabolite-mineral sorption.
Measurement Methods
Both telluric and magnetotelluric methods are used for exploring the structure beneath the Earth’s surface (such as in industrial prospecting). For mineral exploration the targets are any subsurface structure with a distinguishable resistance in comparison to its surroundings.
Data from resistivity surveys are customarily presented and interpreted in the form of values of apparent resistivity (ρa). Apparent resistivity is defined as the resistivity of an electrically homogeneous and isotropic half-space that would yield the measured relationship between the applied current and the potential difference for a particular arrangement and spacing of electrodes. An equation giving the apparent resistivity in terms of applied current, distribution of potential, and arrangement of electrodes can be arrived at through an examination of the potential distribution due to a single current electrode. The effect of an electrode pair (or any other combination) can be found by superposition. Consider a single point electrode, located on the boundary of a semi-infinite, electrically homogeneous medium, which represents a fictitious homogeneous earth. If the electrode carries a current I, measured in amperes (a), the potential at any point in the medium or on the boundary is given by:
v=ρ I/2πd………………………………………………………………………. (i)
Where, V = potential in voltage
ρ = resistivity of the medium,
d = distance between the electrodes.
CHAPTER 4
MATERIALS AND METHODS
4.1 Introduction
Data acquisition technique involved measurement of ground current potentials in two counties (Nairobi city and Kajiado) at different profiles so as to cover enough area of study. Electrical analysis of data collected to determine the existence of telluric current potentials was also done. The areas of study were selected due to different concentrations of underground structures in the two locations hence basis of comparison.
Telluric current potentials were recorded using EX542 Industrial Multimeter/Data logger.
4.1.1 Area of study
Embakasi is in Nairobi’s Eastlands area, south-east of Nairobi County and slightly more than one third of Nairobi’s Industrial Area. Kenya Railways Corporation is developing a new standard gauge railway (SGR) line for passengers and cargo transportation between Mombasa and Nairobi that passes through Embakasi. Ministry of Energy and Petroleum (MoEP) through Kenya Pipeline Company operates an expansive underground infrastructure for petroleum products within Embakasi area. Jomo Kenyatta International Airport, the main airport of Nairobi is located in Embakasi. The Nairobi City Water & Sewerage Company Ltd, a subsidiary of the County Government of Nairobi has its infrastructure widely underground in Embakasi area. ICT and telecommunications service providers such as Safaricom Ltd, Telkom Kenya are increasingly expanding their networks both commercially and domestically in Embakasi area, more specifically, underground fiber cable connectivity. The area is underlain by tertiary volcanics, the main soils types in the area is black clay. Considering the stated activities in this location, it therefore attracts the study on telluric currents.
On the other hand, Ongata Rongai is in Kajiado County, situated 17 km south of Nairobi and west of Ngong hills. Unlike Embakasi, Ongata Rongai has low underground Electrical, Electronics and Telecommunication installation and this makes it a good choice for this research in terms of measurement of telluric currents for data comparison.
Figure 1: Embakasi Location Map
Figure 2: Ongata Rongai Location Map
4.2 Data measurement
Telluric current measurements and data recordings were done in a setup shown in figure 3 using electromagnetic geophysical method (telluric current method) which is not very sensitive to resistivity structure beneath. Focus was on the variations of telluric currents, which are low frequency electric currents that move near the surface of the earth.
The study was concerned with the behavior of fields observed on the earth’s uniform surface.
Figure 3: Block diagram of telluric current measurement
The investigation covered an area of 10000 m2, consisting of three profiles; 1 m spacing between the electrodes, 5 m spacing between the electrodes and 10 m spacing between the electrodes drilled 30 cm into the ground for 24 hours on each profile per location. The telluric currents were recorded using EX542: 12 Function Wireless 433 MHz True Root Mean Square (RMS) Industrial Multimeter/Data logger with the following features:
True RMS measurements for accurate AC Voltage and Current measurements
AC/DC Voltage & Current, Resistance, Capacitance, Frequency electrical/electronic, Temperature, Duty Cycle, Diode/Continuity
Data Acquisition Mode for real time data transmission directly to a PC.
4.3 Data Reduction
Data reduction is the transformation of numerical or alphabetical digital information derived empirically or experimentally into a corrected, ordered, and simplified form. The basic concept is the reduction of multitudinous amounts of data down to the meaningful parts.
When information is derived from instrument readings there may also be a transformation from analog to digital form. When the data are already in digital form the ‘reduction’ of the data typically involves some editing, scaling, encoding, sorting, collating, and producing tabular summaries. When the observations are discrete but the underlying phenomenon is continuous then smoothing and interpolation are often needed. Often the data reduction is undertaken in the presence of reading or measurement errors. Some idea of the nature of these errors is needed before the most likely value may be determined
The reduction of telluric current data was necessary to minimize causes of telluric current variations other than those arising from telluric effects of the earth. In addition, since the profiles were more than one and the duration for recording data was 24 hours, the amount of data recorded was huge; therefore data reduction was necessary to ensure amplitudes of interest were considered.
4.4 Data Processing
Data processing is the conversion of data into usable and desired form. This conversion or “processing” is carried out using a predefined sequence of operations either manually or automatically. Most of the data processing is done by using computers and thus done automatically. The output or “processed” data can be obtained in different forms like image, graph, table, vector file, audio, charts or any other desired format depending on the software or method of data processing used. When done itself it is referred to as automatic data processing.
The telluric data collected in the study area enabled the preparation of dataset for ease of interpretation. From the reduced telluric data, a 2 dimension (2D) model was plotted based on the two variables (current versus time and voltage versus time).
4.5 Data Presentation, Analysis and Interpretation
There are several methods of presenting telluric current data, namely: Non graphical techniques and Graphical techniques. Graphical method was adopted in the study since information could be compared in terms of graphical representation.
Data presented was then analyzed and interpreted for determination of the possible effects of telluric currents on miniaturized electrical, electronic and telecommunication devices and systems in the area of study. From the data, interpretation was done based on amplitudes of telluric currents in the area of study.
Data processing, interpretation and presentation were done using specialized software known as Statistica.
Statistica can be used together with other applications without modification to the existing platform. It is offered as absolute interactive software.
CHAPTER 5
RESULTS AND DISCUSSION
5.1 Introduction
In this chapter, results and detailed discussions of the study are presented.
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11:46:00 AM 0.159 11:20:00 AM 0.175 10:50:00 AM 0.18
11:48:00 AM 0.159 11:22:00 AM 0.175 10:52:00 AM 0.18
11:50:00 AM 0.158 11:24:00 AM 0.175 10:54:00 AM 0.18
11:52:00 AM 0.158 11:26:00 AM 0.174 10:56:00 AM 0.18
11:54:00 AM 0.158 11:28:00 AM 0.175 10:58:00 AM 0.178
11:56:00 AM 0.159 11:30:00 AM 0.174 11:00:00 AM 0.18
11:58:00 AM 0.158 11:32:00 AM 0.175 11:02:01 AM 0.177
12:00:00 PM 0.158 11:34:00 AM 0.175 11:04:00 AM 0.177
12:02:00 PM 0.158 11:36:00 AM 0.174 11:06:00 AM 0.182
12:04:00 PM 0.158 11:38:00 AM 0.173 11:08:00 AM 0.176
12:06:00 PM 0.158 11:40:00 AM 0.173 11:10:00 AM 0.176
12:08:00 PM 0.158 11:42:00 AM 0.173 11:12:00 AM 0.174
12:10:00 PM 0.157 11:44:00 AM 0.173 11:14:00 AM 0.176
12:12:00 PM 0.158 11:46:00 AM 0.173 11:16:00 AM 0.176
12:14:01 PM 0.158 11:48:00 AM 0.173 11:18:00 AM 0.176
12:16:00 PM 0.157 11:50:00 AM 0.173 11:20:00 AM 0.176
12:18:00 PM 0.159 11:52:00 AM 0.172 11:22:00 AM 0.176
12:20:00 PM 0.16 11:54:00 AM 0.173 11:24:00 AM 0.187
12:22:01 PM 0.159 11:56:00 AM 0.172 11:26:00 AM 0.186
12:24:00 PM 0.16 11:58:00 AM 0.172 11:28:00 AM 0.186
12:26:00 PM 0.16 12:00:00 PM 0.172 11:30:00 AM 0.186
12:28:00 PM 0.16 12:02:00 PM 0.172 11:32:00 AM 0.186
12:30:00 PM 0.159 12:04:00 PM 0.173 11:34:00 AM 0.186
12:32:00 PM 0.16 12:06:01 PM 0.173 11:36:00 AM 0.186
12:34:00 PM 0.159 12:08:00 PM 0.173 11:38:00 AM 0.186
12:36:00 PM 0.159 12:10:00 PM 0.173 11:40:00 AM 0.186
12:38:00 PM 0.158 12:12:00 PM 0.173 11:42:00 AM 0.185
12:40:00 PM 0.158 12:14:00 PM 0.173 11:44:00 AM 0.185
12:42:00 PM 0.158 12:16:00 PM 0.173 11:46:00 AM 0.185
12:44:00 PM 0.158 12:18:00 PM 0.173 11:48:00 AM 0.185
12:46:00 PM 0.158 12:20:00 PM 0.173 11:50:00 AM 0.185
12:48:00 PM 0.159 12:22:00 PM 0.173 11:52:00 AM 0.185
12:50:00 PM 0.159 12:24:00 PM 0.173 11:54:00 AM 0.184
12:52:00 PM 0.158 12:26:00 PM 0.173 11:56:00 AM 0.184
12:54:00 PM 0.158 12:28:00 PM 0.174 11:58:00 AM 0.185
12:56:00 PM 0.158 12:30:00 PM 0.172 12:00:00 PM 0.185
12:58:00 PM 0.157 12:32:00 PM 0.171 12:02:00 PM 0.185
1:00:00 PM 0.156 12:34:00 PM 0.171 12:04:00 PM 0.185
1:02:00 PM 0.155 12:36:00 PM 0.171 12:06:00 PM 0.185
1:04:00 PM 0.155 12:38:00 PM 0.171 12:08:00 PM 0.184
1:06:00 PM 0.155 12:40:00 PM 0.171 12:10:00 PM 0.185
1:08:00 PM 0.155 12:42:00 PM 0.171 12:12:00 PM 0.184
1:10:00 PM 0.155 12:44:00 PM 0.171 12:14:00 PM 0.184
1:12:00 PM 0.155 12:46:00 PM 0.171 12:16:00 PM 0.184
1:14:00 PM 0.154 12:48:00 PM 0.172 12:18:00 PM 0.184
1:16:00 PM 0.154 12:50:00 PM 0.172 12:20:00 PM 0.184
1:18:00 PM 0.155 12:52:00 PM 0.173 12:22:00 PM 0.184
1:20:00 PM 0.154 12:54:00 PM 0.173 12:24:00 PM 0.184
1:22:00 PM 0.155 12:56:00 PM 0.173 12:26:00 PM 0.183
1:24:00 PM 0.155 12:58:00 PM 0.173 12:28:00 PM 0.184
1:26:00 PM 0.154 1:00:00 PM 0.173 12:30:00 PM 0.183
1:28:00 PM 0.153 1:02:00 PM 0.173 12:32:00 PM 0.184
1:30:00 PM 0.154 1:04:00 PM 0.173 12:34:00 PM 0.183
1:32:00 PM 0.154 1:06:00 PM 0.173 12:36:00 PM 0.183
1:34:00 PM 0.154 1:08:00 PM 0.172 12:38:00 PM 0.183
1:36:00 PM 0.154 1:10:00 PM 0.172 12:40:00 PM 0.183
1:38:00 PM 0.154 1:12:00 PM 0.172 12:42:00 PM 0.183
1:40:00 PM 0.155 1:14:00 PM 0.171 12:44:00 PM 0.182
1:42:00 PM 0.155 1:16:00 PM 0.171 12:46:00 PM 0.182
1:44:00 PM 0.154 1:18:00 PM 0.171 12:48:00 PM 0
1:46:00 PM 0.154 1:20:00 PM 0.17 12:50:00 PM 0.259
1:48:00 PM 0.154 1:22:00 PM 0.171 12:52:00 PM 0.187
Table 1. Telluric currents measured at 1m, 5m and 10 meter profiles respectively in Nairobi County.
Figure 4. Scatterplot of telluric current against time at 1m profile in Nairobi County
Figure 5. Scatterplot of telluric current against time at 5m profile in Nairobi County
Figure 6. Scatterplot of telluric current against time at 10m profile in Nairobi County
Table 2. Telluric currents measured at 1m, 5m and 10 meter profiles respectively in Kajiado County.
25/01/2019 (1m profile) mA 28/01/2019 (5m profile) mA 30/01/2019 (10 m profile) mA
12:00:00 PM 0.094 12:18:12 PM 0.097 9:42:34 AM 0.196
12:02:00 PM 0.095 12:20:00 PM 0.113 9:44:00 AM 0.708
12:04:00 PM 0.094 12:22:00 PM 0.104 9:46:00 AM 0.336
12:06:00 PM 0.093 12:24:00 PM 0.097 9:48:00 AM 0.884
12:08:00 PM 0.094 12:26:00 PM 0.106 9:50:00 AM 0.912
12:10:00 PM 0.094 12:28:00 PM 0.106 9:52:00 AM 0.761
12:12:00 PM 0.094 12:30:00 PM 0.112 9:54:00 AM 0.155
12:14:00 PM 0.094 12:32:00 PM 0.085 9:56:00 AM 0.971
12:16:00 PM 0.094 12:34:00 PM 0.112 9:58:00 AM 0.189
12:18:00 PM 0.094 12:36:00 PM 0.09 10:00:00 AM 0.868
12:20:00 PM 0.094 12:38:00 PM 0.099 10:02:00 AM 0.624
12:22:00 PM 0.094 12:40:00 PM 0.097 10:04:00 AM 0.051
12:24:00 PM 0.095 12:42:00 PM 0.091 10:06:00 AM 0.878
12:26:00 PM 0.093 12:44:00 PM 0.105 10:08:00 AM 0.599
12:28:00 PM 0.094 12:46:00 PM 0.089 10:10:00 AM 0.791
12:30:00 PM 0.094 12:48:00 PM 0.095 10:12:00 AM 0.688
12:32:00 PM 0.092 12:50:00 PM 0.094 10:14:00 AM 0.736
12:34:00 PM 0.093 12:52:00 PM 0.115 10:16:00 AM 0.936
12:36:00 PM 0.094 12:54:00 PM 0.091 10:18:00 AM 0.67
12:38:00 PM 0.094 12:56:00 PM 0.092 10:20:00 AM 0.556
12:40:00 PM 0.093 12:58:00 PM 0.093 10:22:00 AM 0.903
12:42:00 PM 0.093 1:00:00 PM 0.098 10:24:00 AM 0.959
12:44:00 PM 0.094 1:02:00 PM 0.093 10:26:00 AM 0.868
12:46:00 PM 0.092 1:04:00 PM 0.1 10:28:00 AM 0.631
12:48:00 PM 0.095 1:06:00 PM 0.109 10:30:00 AM 0.863
12:50:00 PM 0.094 1:08:00 PM 0.092 10:32:00 AM 0.844
12:52:00 PM 0.094 1:10:00 PM 0.099 10:34:00 AM 0.028
12:54:00 PM 0.094 1:12:00 PM 0.097 10:36:00 AM 0.972
12:56:00 PM 0.094 1:14:00 PM 0.084 10:38:00 AM 0.462
12:58:00 PM 0.094 1:16:00 PM 0.087 10:40:00 AM 0.909
1:00:00 PM 0.093 1:18:00 PM 0.11 10:42:00 AM 0.476
1:02:00 PM 0.095 1:20:00 PM 0.092 10:44:00 AM 0.483
1:04:00 PM 0.095 1:22:00 PM 0.102 10:46:00 AM 0.79
1:06:00 PM 0.095 1:24:00 PM 0.098 10:48:00 AM 0.1
1:08:00 PM 0.094 1:26:00 PM 0.091 10:50:00 AM 0.751
1:10:00 PM 0.094 1:28:00 PM 0.095 10:54:00 AM 0.69
1:12:00 PM 0.095 1:30:00 PM 0.091 10:56:00 AM 0.93
1:14:00 PM 0.094 1:32:00 PM 0.096 10:58:00 AM 0.612
1:16:00 PM 0.094 1:34:00 PM 0.088 11:00:00 AM 0.556
1:18:00 PM 0.093 1:36:00 PM 0.095 11:02:00 AM 0.884
1:20:00 PM 0.094 1:38:00 PM 0.091 11:04:00 AM 0.632
1:22:00 PM 0.094 1:40:00 PM 0.099 11:06:00 AM 0.617
1:24:00 PM 0.094 1:42:00 PM 0.096 11:08:00 AM 0.413
1:26:00 PM 0.095 1:44:00 PM 0.099 11:10:00 AM 0.355
1:28:00 PM 0.094 1:46:00 PM 0.094 11:12:00 AM 0.5
1:30:00 PM 0.094 1:48:00 PM 0.102 11:14:00 AM 0.606
1:32:00 PM 0.094 1:50:00 PM 0.087 11:16:00 AM 0.588
1:34:00 PM 0.092 1:52:00 PM 0.091 11:18:00 AM 0.253
1:36:00 PM 0.095 1:54:00 PM 0.088 11:20:00 AM 0.188
1:38:00 PM 0.095 1:56:00 PM 0.095 11:22:00 AM 0.199
1:40:00 PM 0.095 1:58:00 PM 0.106 11:24:00 AM 0.16
1:42:00 PM 0.095 2:00:00 PM 0.094 11:26:00 AM 0.023
1:44:00 PM 0.095 2:02:00 PM 0.105 11:28:00 AM 0.988
1:46:00 PM 0.094 2:04:00 PM 0.096 11:30:00 AM 0.902
1:48:00 PM 0.095 2:06:00 PM 0.092 11:32:00 AM 0.343
1:50:00 PM 0.094 2:08:00 PM 0.11 11:34:00 AM 0.164
1:52:00 PM 0.096 2:10:00 PM 0.098 11:36:00 AM 0.206
1:54:00 PM 0.095 2:12:00 PM 0.091 11:38:00 AM 0.321
1:56:00 PM 0.094 2:14:00 PM 0.11 11:40:00 AM 0.497
1:58:00 PM 0.095 2:16:00 PM 0.103 11:40:40 AM 0.363
2:00:00 PM 0.096 2:18:00 PM 0.104 11:42:00 AM 0.417
2:02:00 PM 0.095 2:20:01 PM 0.097 11:44:00 AM 0.48
2:04:00 PM 0.095 2:22:00 PM 0.102 11:46:00 AM 0.323
2:06:00 PM 0.094 2:24:00 PM 0.091 11:48:00 AM 0.675
2:08:00 PM 0.094 2:26:00 PM 0.1 11:50:00 AM 0.725
2:10:00 PM 0.095 2:28:00 PM 0.109 11:52:00 AM 0.72
2:12:00 PM 0.095 2:30:00 PM 0.097 11:54:00 AM 0.528
2:14:00 PM 0.095 2:32:00 PM 0.11 11:56:00 AM 0.645
2:16:00 PM 0.095 2:34:00 PM 0.105 11:58:00 AM 0.462
2:18:00 PM 0.095 2:36:00 PM 0.099 12:00:00 PM 0.451
2:20:00 PM 0.096 2:38:00 PM 0.102 12:02:00 PM 0.364
2:22:00 PM 0.095 2:40:00 PM 0.105 12:04:00 PM 0.432
2:24:00 PM 0.094 2:42:00 PM 0.099 12:06:00 PM 0.095
2:26:00 PM 0.094 2:44:00 PM 0.11 12:08:00 PM 0.808
2:28:00 PM 0.095 2:46:00 PM 0.106 12:10:00 PM 0.773
2:30:00 PM 0.095 2:48:00 PM 0.099 12:12:00 PM 0.569
2:32:00 PM 0.095 2:50:00 PM 0.099 12:14:00 PM 0.027
2:34:00 PM 0.095 2:52:00 PM 0.097 12:16:00 PM 0.365
2:36:00 PM 0.095 2:54:00 PM 0.11 12:18:00 PM 0.611
2:38:00 PM 0.095 2:56:00 PM 0.096 12:20:00 PM 0.617
2:40:00 PM 0.095 2:58:00 PM 0.102 12:22:00 PM 0.775
2:42:00 PM 0.094 3:00:00 PM 0.103 12:24:00 PM 0.029
2:44:00 PM 0.095 3:02:00 PM 0.099 12:26:00 PM 0.934
2:46:00 PM 0.096 3:04:00 PM 0.102 12:28:00 PM 0.877
2:48:00 PM 0.096 3:06:00 PM 0.095 12:30:00 PM 0.135
2:50:00 PM 0.096 3:08:00 PM 0.102 12:32:00 PM 0.212
2:52:00 PM 0.096 3:10:00 PM 0.106 12:34:01 PM 0.974
2:54:00 PM 0.095 3:12:00 PM 0.107 12:36:00 PM 0.607
2:56:00 PM 0.096 3:14:00 PM 0.106 12:38:00 PM 0.693
2:58:00 PM 0.096 3:16:00 PM 0.105 12:40:00 PM 0.45
3:00:00 PM 0.095 3:18:00 PM 0.11 12:42:00 PM 0.511
3:02:00 PM 0.095 3:20:00 PM 0.105 12:44:00 PM 0.769
3:04:00 PM 0.097 3:22:00 PM 0.108 12:46:00 PM 0.699
3:06:00 PM 0.096 3:24:00 PM 0.106 12:48:00 PM 0.52
3:08:00 PM 0.096 3:26:00 PM 0.11 12:50:00 PM 0.498
3:10:00 PM 0.096 3:28:00 PM 0.104 12:52:00 PM 0.032
3:12:00 PM 0.096 3:30:00 PM 0.103 12:54:00 PM 0.816
3:14:00 PM 0.096 3:32:00 PM 0.115 12:56:00 PM 0.442
3:16:00 PM 0.097 3:34:00 PM 0.098 12:58:00 PM 0.55
3:18:00 PM 0.095 3:36:00 PM 0.109 1:00:00 PM 0.188
3:20:00 PM 0.095 3:38:00 PM 0.105 1:02:00 PM 0.956
3:22:00 PM 0.094 3:40:00 PM 0.117 1:04:00 PM 0.118
3:24:00 PM 0.095 3:42:00 PM 0.103 1:06:00 PM 0.158
3:26:00 PM 0.095 3:44:00 PM 0.107 1:08:00 PM 0.839
3:28:00 PM 0.096 3:46:00 PM 0.102 1:10:00 PM 0.498
3:30:00 PM 0.096 3:48:00 PM 0.107 1:12:00 PM 0.446
3:32:00 PM 0.097 3:50:00 PM 0.104 1:14:00 PM 0.569
3:34:00 PM 0.095 3:52:00 PM 0.104 1:16:00 PM 0.388
3:36:00 PM 0.096 3:54:00 PM 0.1 1:18:00 PM 0.621
3:38:00 PM 0.096 3:56:00 PM 0.108 1:20:00 PM 0.433
3:40:00 PM 0.096 3:58:00 PM 0.107 1:22:00 PM 0.559
3:42:00 PM 0.096 4:00:00 PM 0.102 1:24:00 PM 0.614
3:44:00 PM 0.095 4:02:00 PM 0.105 1:26:00 PM 0.832
3:46:00 PM 0.096 4:04:00 PM 0.108 1:28:00 PM 0.074
3:48:00 PM 0.096 4:06:00 PM 0.109 1:30:00 PM 0.663
3:50:00 PM 0.095 4:08:01 PM 0.107 1:32:00 PM 0.499
3:52:00 PM 0.096 4:10:00 PM 0.104 1:34:00 PM 0.663
3:54:00 PM 0.096 4:12:01 PM 0.12 1:36:00 PM 0.821
3:56:00 PM 0.097 4:14:00 PM 0.107 1:38:00 PM 0.678
3:58:00 PM 0.097 4:16:00 PM 0.103 1:40:00 PM 0.609
4:00:00 PM 0.096 4:18:00 PM 0.104 1:42:00 PM 0.508
4:02:00 PM 0.097 4:20:00 PM 0.103 1:44:00 PM 0.911
4:04:00 PM 0.096 4:22:00 PM 0.103 1:46:00 PM 0.823
4:06:00 PM 0.097 4:24:00 PM 0.103 1:48:00 PM 0.141
4:08:00 PM 0.095 4:26:00 PM 0.107 1:50:00 PM 0.899
4:10:00 PM 0.097 4:28:00 PM 0.105 1:52:01 PM 0.027
4:12:00 PM 0.097 4:30:00 PM 0.104 1:54:00 PM 0.859
4:14:00 PM 0.096 4:32:00 PM 0.106 1:56:00 PM 0.025
4:16:00 PM 0.095 4:34:00 PM 0.108 1:58:00 PM 0.227
4:18:00 PM 0.097 4:36:00 PM 0.111 2:00:00 PM 0.879
4:20:00 PM 0.096 4:38:00 PM 0.124 2:02:00 PM 0.869
4:22:00 PM 0.096 4:40:00 PM 0.112 2:04:00 PM 0.976
4:24:00 PM 0.096 4:42:00 PM 0.112 2:06:00 PM 0.91
4:26:00 PM 0.097 4:44:00 PM 0.108 2:08:00 PM 0.317
4:28:00 PM 0.096 4:46:00 PM 0.105 2:10:00 PM 0.129
4:30:00 PM 0.097 4:48:00 PM 0.105 2:12:00 PM 0.074
4:32:00 PM 0.097 4:50:00 PM 0.108 2:14:00 PM 0.677
4:34:00 PM 0.096 4:52:00 PM 0.109 2:16:00 PM 0.983
4:36:00 PM 0.096 4:54:00 PM 0.106 2:18:00 PM 0.297
4:38:00 PM 0.096 4:56:00 PM 0.103 2:20:00 PM 0.636
4:40:00 PM 0.096 4:58:01 PM 0.106 2:22:00 PM 0.11
4:42:00 PM 0.097 5:00:00 PM 0.106 2:24:00 PM 0.325
4:44:00 PM 0.097 5:02:00 PM 0.106 2:26:00 PM 0.47
4:46:00 PM 0.098 5:04:00 PM 0.108 2:28:00 PM 0.316
4:48:00 PM 0.096 5:06:00 PM 0.107 2:30:00 PM 0.972
4:50:00 PM 0.097 5:08:00 PM 0.105 2:32:00 PM 0.814
4:52:00 PM 0.099 5:10:00 PM 0.109 2:34:00 PM 0.773
4:54:00 PM 0.097 5:12:00 PM 0.11 2:36:00 PM 0.693
4:56:00 PM 0.097 5:14:00 PM 0.107 2:38:00 PM 0.81
4:58:00 PM 0.097 5:16:00 PM 0.11 2:40:00 PM 0.61
5:00:00 PM 0.097 5:18:00 PM 0.103 2:42:00 PM 0.712
Figure 7. Scatterplot of telluric current against time at 1m profile in Kajiado County
Figure 8. Scatterplot of telluric current against time at 5m profile in Kajiado County
Figure 9. Scatterplot of telluric current against time at 10m profile in Kajiado County
From the data collected and analyzed, there is a nonlinear behavior of telluric current. Assuming that earth has conductivity other than zero, this current can be expressed as:
j=σΕ …………………………………………………………… (ii)
Amplitudes and periods of the telluric currents fluctuating as a result of electromagnetic variation of earth.
There was a significant change in telluric current amplitudes as spatial distance between the electrodes were adjusted, suggesting that the potential difference between two points A and B on figure 3 can be given by:
VB-VA = ∫_A^B▒Edl ………………………………………………………… (iii)
5.3 Comparison of Telluric current potentials in Kajiado & Nairobi Counties
Table 3: Average telluric current potential at profiles 1m, 5m and 10m in Kajiado & Nairobi counties respectively
Telluric Current Amplitudes in Kajiado (mA) Telluric Current Amplitudes in Nairobi (mA)
1m profile 5m profile 10m profile 1m profile 5m profile 10m profile
0.0951 0.102 0.156 0.159 0.177 0.184
5.4 Error margin in Telluric current potentials in Kajiado & Nairobi Counties
5.5 A practical electronic circuit before subjected to telluric currents
Figure 10: An electronic circuit before subjected to telluric currents
5.6 Effect of telluric current on buried electronic circuit
Figure 11: Cumulative effect of telluric currents on a buried electronic system
5.7 Effect of telluric current on underground communication lines
Figure 12: (a) Typical voice signal over wired Figure 12: (b) Voice signal over communication line. Communication lines exposed to telluric currents.
CHAPTER 6
CONCLUSION AND RECOMMENDATIONS
6.1 Conclusion
From the data recorded, it is evident that telluric current exists as measured at different points on earth’s surface.
Telluric currents initiates or accelerates the process of electrochemical corrosion on energized underground electronics and electrical circuits as in figure 9.
Wired communication lines, between a digital PABX and a terminal device (desktop phone), when exposed to telluric currents experiences an error as a result of cumulative effect of telluric currents which end up isolating the terminal device from connection.
From table 5, telluric current amplitudes are slightly higher in Embakasi compared to Ongata Rongai due to high concentration of underground structures installations.
From the potentials measured, there is need to create a preferred path for the current to discharge from the conducting structures i.e. earthing
Protection against electrochemical corrosion is to ensure that there is a good insulation on the conducting structure.
Electrical shielding may be installed in between the conducting structures and the stray current source.
Installation of electrolysis rectifiers that respond to the dynamic current in the area to provide the cathodic protection.
6.2 Recommendations
Telluric currents investigation carried out in Nairobi city and Kajiado counties cannot be regarded as an end but as a valuable piece of work and a guide to interested underground infrastructural developers and users to ensure electrical hazard free environment. There is need for researchers to consider study on underground currents in local environments to ensure that research on telluric currents is not ignored.
Based on electrical potentials measured, it is highly recommended to use electrical shielding in between the conducting structures and the stray current source.
For improved amplitudes of the telluric current potentials, use highly conducting materials as electrodes, such as silver coated electrodes.
This research work was carried out in Nairobi and Kajiado Counties. I further recommend the same study to be conducted on other counties with various underground structure and soil formations.
REFERENCES
Boteler, D.H, (2003). Geomagnetic Hazards to Conducting Networks. Journal on Natural Hazards 28, (2–3): 537–561.
Arora, (1999). Overview of Geomagnetic Deep Soundings (Gds) as Applied in the Parnaíba Basin, North-Northeast Brazil. New Age International (P) Limited, New Delhi.
Daniel S., (2014). Review of Mechanisms which Causes Telluric Currents in the Lithosphere. Annals of Geophysics 56, (5): 1-17.
Fraser Smith and Coates, (1978). The Earth’s Electrical Environment: 247. National Academy Press, Washington, D.C.
K. Vozoff, (1972). The Magnetotelluric method in the exploration of sedimentary basins. Geophysics 62, (2 – 37): 98-141.
Louis,Lanzerotti and Giovanni, P. Gregori,(1986). The Earth’s Electrical Environment. 232 – 250. The National Academies Press, Rome.
Russell (1986), Engebretson et al., (1995). Monitoring of the Telluric Currents Originated by Solar Related Atmospheric Events in Northwestern Turkey. 205: 208-215.
Turkish Journal of Electrical Engineering and Computer Sciences. Investigation of the telluric effects arising along the cathodically protected natural gas pipeline between Karadeniz Ereğli and Düzce (2013) 21, (3): 758 – 765. Scientific and Technological Research Council of Turkey.
Wallace H. Campbell, (1980). Observation of Electric Currents in the Alaska Oil Pipeline resulting from Auroral Electrojet Current Sources. Geophysical Journal of the Royal Astronomical Society Banner, 61 (2).
APPENDIX A
A list of the areas of study in Nairobi and Kajiado counties
Embakasi is in Nairobi’s Eastlands area, south-east of Nairobi County and slightly more than one third of Nairobi’s Industrial Area. Kenya Railways Corporation is developing a new standard gauge railway (SGR) line for passengers and cargo transportation between Mombasa and Nairobi that passes through Embakasi. Ministry of Energy and Petroleum (MoEP) through Kenya Pipeline Company operates an expansive underground infrastructure for petroleum products within Embakasi area. Jomo Kenyatta International Airport, the main airport of Nairobi is located in Embakasi. The Nairobi City Water & Sewerage Company Ltd, a subsidiary of the County Government of Nairobi has its infrastructure widely underground in Embakasi area. ICT and telecommunications service providers such as Safaricom Ltd, Telkom Kenya are increasingly expanding their networks both commercially and domestically in Embakasi area, more specifically, underground fiber cable connectivity. The area is underlain by tertiary volcanics, the main soils types in the area is black clay. Considering the stated activities in this location, it therefore attracts the study on telluric currents.
On the other hand, Ongata Rongai is in Kajiado County, situated 17 km south of Nairobi and west of Ngong hills. Unlike Embakasi, Ongata Rongai has low underground Electrical, Electronics and Telecommunication installation and this makes it a good choice for this research in terms of measurement of telluric currents for data comparison
APENDIX B
The types of telluric current
Shallow telluric currents: effects on shallow telluric currents can be found whenever a mineral has some remarkably different electrical conductivity compared to that of the surrounding materials. This gives rise to allocalised conductivity anomaly that can be studied by means of a dense network of recording instruments.
Shallow currents has been reported in several sedimental basins such as in the Seine basin and in the northern Germany anomaly (Gregory et al., 1982) these currents are responsible for a component of the magnetic signals where the geometrical orientation of the magnetic evaluations at higher frequencies are correlated with the shape of the signals. The different between the deep and shallow effects has been shown by Honkura (1974).
At shorter periods, when the skin depth is shallower the coast effect reflects the coast shape. At longer periods electromagnetic induction evidence suggest a dependence upon the downward bending of the lithospheric slab.
Deep telluric current: The behavior of the telluric current is controlled by the shape of the isotherms however it is noted as the concept of the lithosphere is more complicated whereby the experimental observations has shown different definitions can be distinguished: the elastic or flexual, the thermal, the seismic and the chemical or the mineralogical (Maxwell et al., 1984)
APPENDIX C
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