An Introduction to Applied and Environmental Geophysics E-Book

John M. Reynolds

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 1594

Veröffentlichungsjahr: 2011

Beschreibung

An Introduction to Applied and Environmental Geophysics, 2nd Edition, describes the rapidly developing field of near-surface geophysics. The book covers a range of applications including mineral, hydrocarbon and groundwater exploration, and emphasises the use of geophysics in civil engineering and in environmental investigations. Following on from the international popularity of the first edition, this new, revised, and much expanded edition contains additional case histories, and descriptions of geophysical techniques not previously included in such textbooks.

The level of mathematics and physics is deliberately kept to a minimum but is described qualitatively within the text. Relevant mathematical expressions are separated into boxes to supplement the text. The book is profusely illustrated with many figures, photographs and line drawings, many never previously published. Key source literature is provided in an extensive reference section; a list of web addresses for key organisations is also given in an appendix as a valuable additional resource.

• Covers new techniques such as Magnetic Resonance Sounding, Controlled- Source EM, shear-wave seismic refraction, and airborne gravity and EM techniques
• Now includes radioactivity surveying and more discussions of down-hole geophysical methods; hydrographic and Sub-Bottom Profiling surveying; and UneXploded Ordnance detection
• Expanded to include more forensic, archaeological, glaciological, agricultural and bio-geophysical applications
• Includes more information on physio-chemical properties of geological, engineering and environmental materials
• Takes a fully global approach
• Companion website with additional resources available at www.wiley.com/go/reynolds/introduction2e
• Accessible core textbook for undergraduates as well as an ideal reference for industry professionals

The second edition is ideal for students wanting a broad introduction to the subject and is also designed for practising civil and geotechnical engineers, geologists, archaeologists and environmental scientists who need an overview of modern geophysical methods relevant to their discipline. While the first edition was the first textbook to provide such a comprehensive coverage of environmental geophysics, the second edition is even more far ranging in terms of techniques, applications and case histories.

Leseprobe

Contents

Cover

Title Page

Copyright

Preface to the 2nd Edition

Acknowledgements

1: Introduction

1.1 What are ‘applied’ and ‘environmental’ geophysics?

1.2 Geophysical methods

1.3 Matching geophysical methods to applications

1.4 Planning a geophysical survey

1.5 Geophysical survey design

2: Gravity Methods

2.1 Introduction

2.2 Physical basis

2.3 Measurement of gravity

2.4 Gravity meters

2.5 Corrections to gravity observations

2.6 Interpretation methods

2.7 Applications and case histories

3: Geomagnetic Methods

3.1 Introduction

3.2 Basic concepts and units of geomagnetism

3.3 Magnetic properties of rocks

3.4 The Earth's magnetic field

3.5 Magnetic instruments

3.6 Magnetic surveying

3.7 Qualitative interpretation

3.8 Quantitative interpretation

3.9 Applications and case histories

4: Applied Seismology: Introduction and Principles

4.1 Introduction

4.2 Seismic waves

4.3 Raypath geometry in layered ground

4.4 Loss of seismic energy

4.5 Seismic energy sources

4.6 Detection and recording of seismic waves

5: Seismic Refraction Surveying

5.1 Introduction

5.2 General principles of refraction surveying

5.3 Geometry of refracted raypaths

5.4 Interpretational methods

5.5 Applications and case histories

5.6 Shear wave methods

6: Seismic Reflection Surveying

6.1 Introduction

6.2 Reflection surveys

6.3 Reflection data processing

6.4 Correlating seismic data with borehole logs and cones

6.5 Interpretation

6.6 Applications

7: Electrical Resistivity Methods

7.1 Introduction

7.2 Basic principles

7.3 Electrode configurations and geometric factors

7.4 Modes of deployment

7.5 Interpretation methods

7.6 ERT applications and case histories

7.7 Mise-à-la-masse (MALM) method

7.8 Leak detection through artificial membranes

8: Spontaneous (Self) Potential Methods

8.1 Introduction

8.2 Occurrence of self-potentials

8.3 Origin of self-potentials

8.4 Measurement of self-potentials

8.5 Corrections to SP data

8.6 Interpretation of self-potential anomalies

8.7 Applications and case histories

8.8 Electrokinetic (EK) surveying

9: Induced Polarisation

9.1 Introduction

9.2 Origin of induced polarisation effects

9.3 Measurement of induced polarisation

9.4 Applications and case histories

10: Electromagnetic Methods: Introduction and Principles

10.1 Introduction

10.2 Principles of EM surveying

10.3 Airborne EM surveying

10.4 Seaborne EM surveying

10.5 Borehole EM surveying

11: Electromagnetic Methods: Systems and Applications

11.1 Introduction

11.2 Continuous-wave (CW) systems

11.3 Pulse-transient (TEM) or time-domain (TDEM) EM systems

12: Electromagnetic Methods: Systems and Applications II

12.1 Very-low-frequency (VLF) methods

12.2 The telluric method

12.3 The magnetotelluric (MT) method

12.4 Magnetic Resonance Sounding (MRS)

13: Introduction to Ground-Penetrating Radar

13.1 Introduction

13.2 Principles of operation

13.3 Propagation of radiowaves

13.4 Dielectric properties of earth materials

13.5 Modes of data acquisition

13.6 Data processing

13.7 Interpretation techniques

14: Ground-Penetrating Radar: Applications and Case Histories

14.1 Geological mapping

14.2 Hydrogeology and groundwater contamination

14.3 Glaciological applications

14.4 Engineering applications on manmade structures

14.5 Voids within manmade structures

14.6 Archaeological investigations

14.7 Forensic uses of GPR

14.8 Wide-aperture radar mapping and migration processing

14.9 Borehole radar

14.10 UXO and landmine detection

14.11 Animals

15: Radiometrics

15.1 Introduction

15.2 Natural radiation

15.3 Radioactivity of rocks

15.4 Radiation detectors

15.5 Data correction methods

15.6 Radiometric data presentation

15.7 Case histories

Appendix 1: Web addresses

Learned societies

Other organisations

References

Index

This edition first published 2011 © 2011 by John Wiley & Sons, Ltd.

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Library of Congress Cataloging-in-Publication Data

Reynolds, John M. An introduction to applied and environmental geophysics / John M. Reynolds. – 2nd ed. p. cm. Includes index. Summary: “The book covers a range of applications including mineral and hydrocarbon exploration but the greatest emphasis is on the use of geophysics in civil engineering, and in environmental and groundwater investigations” – Provided by publisher. ISBN 978-0-471-48535-3 (hardback) 978-0-471-485360 (paperback) 1. Geophysics–Technique. 2. Seismology–Technique. I. Title. QC808.5.R49 2011 624.1′51–dc22 2010047246

A catalogue record for this book is available from the British Library.

This book is published in the following electronic format: ePDF 9780470975015, ePub 9780470975442

First Impression 2011

Preface to the 2nd Edition

The idea for this book originated in 1987 while I was preparing for lectures on courses in applied geology and environmental geophysics at Plymouth Polytechnic (now the University of Plymouth), Devon, England. Students who had only very basic mathematical skills and little if any physics background found most of the so-called ‘introductory’ texts difficult to follow owing to the perceived opacity of text and daunting display of apparently complex mathematics. To junior undergraduates, this is immediately offputting and geophysics becomes known as a ‘hard’ subject and one to be avoided at all costs.

I hope that the information on the pages that follow will demonstrate the range of applications of modern geophysics – most now very well established, others very much in the early stages of implementation. It is also hoped that the book will provide a foundation on which to build if the reader wishes to take the subject further. The references cited, by no means exhaustive, have been included to provide pointers to more detailed discussions.

The aim of this book is to provide a basic introduction to geophysics, keeping the mathematics and theoretical physics to a minimum and emphasising the applications. Considerable effort has been expended in compiling a representative set of case histories that demonstrate clearly the issues being discussed.

The first edition of this book was different from other introductory texts in that it paid attention to a great deal of new material, or topics not previously discussed in detail: for example, geophysical survey design and line optimisation techniques, image-processing of potential field data, recent developments in high-resolution seismic reflection profiling, electrical resistivity Sub-Surface Imaging (tomography), Spectral Induced Polarisation, and Ground Penetrating Radar, amongst many other subjects, which until 1997, when the first edition was published, had never featured in detail in such a book. While retaining much of the basic theory and principles from the first edition, the scope of material has been expanded considerably in the second edition to reflect the changes and developments in the subject. Consequently, there is much new material. Many new and unpublished case histories from commercial projects have been included along with recently published examples of applications.

The subject material has been developed over a number of years, firstly while I was at Plymouth, and secondly and more recently while I have been working as a geophysical consultant. Early drafts of the first edition book were tried out on several hundred second- and third-year students who were unwitting ‘guinea pigs’ – their comments have been very helpful. While working in industry, I have found the need for an introductory book all the more evident. Many potential clients either appear unaware of how geophysics could possibly be of help to them, or have a very dated view as to the techniques available. There has been no suitable book to recommend to them that explained what they needed and wanted to know or that provided real examples.

Since publication of the first edition, the development of new instruments, improved data processing and interpretation software and increased understanding of physical processes have continued at a seemingly ever-faster rate. Much of this has also been fuelled by the availability of ever more powerful computers and associated technology. It has been difficult keeping abreast of all the new ideas, especially with an ever-growing number of scientific publications and the huge resource now available through the Internet. What is exciting is that the changes are still occurring and we can expect to see yet more novel developments over the next few years. We have seen new branches of the science develop, such as in forensic, agro- and bio-geophysics, as well as techniques mature, particularly in environmental geophysics and applications to contaminated land, for example. There has been a move away from just mapping to more monitoring and time-lapse surveys. There has also been a greater blurring of the boundaries between industrial sectors. Hydrocarbon exploration analytical techniques are now being used in ultra-high resolution engineering investigations, and electromagnetic methods have ventured offshore to become established in hydrocarbon exploration, just two examples amongst many.

It is my hope that this book will be seen as providing a broad overview of applied and environmental geophysics methods, illustrating the power and sophistication of the various techniques, as well as the limitations. If this book helps in improving the acceptance of geophysical methods and in increasing the awareness of the methods available, then it will have met its objective. There is no doubt that applied and environmental geophysics have an important role to play, and that the potential for the future is enormous.

It is inevitable with a book of this kind that brand names, instrument types, and specific manufacturers are named. References to such information does not constitute an endorsement of any product and no preference is implied, nor should any inference be drawn over any omissions. In books of this type the material covered tends to be flavoured by the interests and experience of the author, and I am sure that this one is no exception. I hope that what is included is a fair reflection of the current state of applied and environmental geophysics. Should any readers have any case histories that they feel are of particular significance, I should be most interested to receive them for possible inclusion at a later date. Also, any comments or corrections that readers might have would be gratefully received.

Another major difference with this edition is that while all the figures included herein are published in black and white greyscale, colour versions of many are included on an accompanying website at: www.wiley.com/go/reynolds/introduction2e, along with the list of web URLs given in the Appendix. Furthermore, the book is also available in electronic form in its entirety and also as e-chapters, all of which are available for purchase through the Wiley website at www.wiley.com.

The figures with a [C] in the captions indicates that the full colour version is available on the website.

Acknowledgements

Thanks are due to the many companies that have very kindly supplied material, and colleagues around the world for permitting extracts of their work to be reproduced as well as their kind comments about the first edition. A key feature of any technical book is the graphical material. Most of the figures that featured in the first edition and have been used in the second have been redrawn or updated; there have been many brand new figures and extensive graphical work done to enhance the material presented. I must show due recognition to a number of people who have assisted with this mammoth task and worked on the figures for me, especially Holly Rowlands, who has undertaken the majority of this work. Thanks are also due to my colleague Dr Lucy Catt for technical discussions and for her contribution in generating a number of the figures. I must also thank the editorial and production staff at John Wiley & Sons Ltd for their understanding and patience in waiting so long for the final manuscript, especially Fiona Woods and Rachael Ballard.

My final acknowledgement must be to my wife, Moira, for her support, encouragement and long-suffering patience while I have been closeted with ‘The Book’. Without her help, encouragement and forbearance, this second edition would never have been completed.

John M. Reynolds Mold, Flintshire, North Wales, UKMay 2010

1

Introduction

1.1 What are ‘applied’ and ‘environmental’ geophysics?

In the broadest sense, the science of geophysics is the application of physics to investigations of the Earth, Moon and planets. The subject is thus related to astronomy. Normally, however, the definition of ‘geophysics’ is used in a more restricted way, being applied solely to the Earth. Even then, the term includes such subjects as meteorology and ionospheric physics, and other aspects of atmospheric sciences.

To avoid confusion, the use of physics to study the interior of the Earth, from land surface to the inner core, is known as solid earth geophysics. This can be subdivided further into global geophysics, or alternatively pure geophysics, which is the study of the whole or substantial parts of the planet, and applied geophysics, which is concerned with investigating the Earth's crust and near-surface to achieve a practical and, more often than not, an economic aim.

‘Applied geophysics’ covers everything from experiments to determine the thickness of the crust (which is important in hydrocarbon exploration) to studies of shallow structures for engineering site investigations, exploring for groundwater and for minerals and other economic resources, to trying to locate narrow mine shafts or other forms of buried cavities, or the mapping of archaeological remains, or locating buried pipes and cables – but where in general the total depth of investigation is usually less than 100 m. The same scientific principles and technical challenges apply as much to shallow geophysical investigations as to pure geophysics. Sheriff (2002: p. 161) has defined ‘applied geophysics’ thus:

Making and interpreting measurements of physical properties of the Earth to determine sub-surface conditions, usually with an economic objective, e.g. discovery of fuel or mineral depositions.

‘Engineering geophysics’ can be described as being:

The application of geophysical methods to the investigation of sub-surface materials and structures that are likely to have (significant) engineering implications.

As the range of applications of geophysical methods has increased, particularly with respect to derelict and contaminated land investigations, the subdiscipline of ‘environmental geophysics’ has developed (Greenhouse, 1991; Steeples, 1991). This can be defined as being:

The application of geophysical methods to the investigation of near-surface bio-physico-chemical phenomena that are likely to have (significant) implications for the management of the local environment.

The principal distinction between engineering and environmental geophysics is more commonly that the former is concerned with structures and types of materials, whereas the latter can also include, for example, mapping variations in pore-fluid conductivities to indicate pollution plumes within groundwater. Chemical effects can be equally as important as physical phenomena. Since the mid-1980s in the UK, geophysical methods have been used increasingly to investigate derelict and contaminated land, with a specific objective of locating polluted areas prior to direct observations using trial pits and boreholes (e.g. Reynolds and Taylor, 1992). Geophysics is also being used much more extensively over landfills and other waste repositories (e.g. Reynolds and McCann, 1992). One of the advantages of using geophysical methods is that they are largely environmentally benign – there is no disturbance of subsurface materials. An obvious example is the location of a corroded steel drum containing toxic chemicals. To probe for it poses the real risk of puncturing it and creating a much more significant pollution incident. By using modern geomagnetic surveying methods, the drum's position can be isolated and a careful excavation instigated to remove the offending object without damage. Such an approach is cost-effective and environmentally safer.

There are obviously situations where a specific site investigation contains aspects of engineering as well as environmental geophysics, and there may well be considerable overlap. Indeed, if each subdiscipline of applied geophysics is considered, they may be represented as shown in Figure 1.1, as overlapping. Also included are six other subdisciplines whose names are largely self-explanatory: namely, agro-geophysics (the use of geophysics for agriculture and soil science), archaeo-geophysics (geophysics in archaeology), bio-geophysics (geophysical manifestation of microbial activity within geological materials), forensic geophysics (the application of geophysical methods to investigations that might come before a court of law), glacio-geophysics (geophysics in glaciology) and hydro-geophysics (geophysics in groundwater investigations; see Pellerin et al. (2009) and accompanying papers). Glacio-geophysics is particularly well established within the polar scientific communities and has been since the 1950s. The application of ground-based geophysical techniques for glaciological studies (and particularly on temperate glaciers) has come of age especially since the early 1990s (see for example the thematic set of papers on the geophysics of glacial and frozen materials, Kulessa and Woodward (2007)). Forensic geophysics is now recognised as a subdiscipline of forensic geoscience (‘geoforensics’; cf. Ruffell and McKinley, 2008) and is used regularly in police investigations in searches for mortal remains, buried bullion, and so on: see Pye and Croft (2003) and Ruffell (2006) for a basic introduction and signposting to other literature. The subdiscipline of bio-geophysics has emerged over the last decade or so (e.g. Williams et al. 2005; Slater and Atekwana, 2009) and examines the geophysical signatures of microbial cells in the Earth, the interaction of micro-organisms and subsurface geological materials, and alteration of the physical and chemical properties of geological materials as a result of microbial activity. The microbial activity may be natural, as in microbial bio-mineralisation, or artificial as in the insertion of bacteria into the ground to remediate diesel spills, for example. Perhaps the newest branch is agro-geophysics (Allred , 2008; Lück and Müller, 2009), which has emerged over the last decade. Recent examples of these applications of geophysics include water retention capacity of agricultural soils (Lück ., 2009, effects of long-term fertilisation on soil properties (Werban , 2009), and influences of tillage on soil moisture content (Müller , 2009).