cover

N. A. Anstey:

Seismic prospection instruments. Volume 1

Signal characteristics and instrument specifications. 2. rev. ed.

1981. X, 154 pages, 115 figures, 17x24cm, 600 g
Language: English

(Geoexploration Monographs, Number 3)

ISBN 978-3-443-13303-0, bound, price: 28.00 €

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Keywords

geoexplorationgeophyiscs

Contents

Synopsis top ↑

This book is intended to offer something to all seismologists, whether their particular concern is with earthquake seismology, or with crustal studies, or with one of the main divisions — data-gathering, data-processing, and interpretation — of seismic prospecting. Primarily, however, the book is addressed to the newcomer to the data-gathering function in seismic prospecting — to the fledgling seismic observer. Seismic observers are recruited both from physics graduates and from electronics engineers. Undoubtedly this is a healthy practice, which has worked well in the past. However, the difference in background makes it difficult to write for both groups without appearing trivial to one or the other.
The book describes fundamentals of the seismic prospecting method as well as the manipulation of waveforms. It deals with the seismic reflection technique and looks at desirable instrument characteristics.

Table of Contents top ↑

Authors’ preface 1st and 2nd edition IX
1 Elements of the seismic prospecting method
1.1 Elements of the seismic prospecting method 1
1.1.1 The basic simplicity1
1.1.2 The seismic disturbance 2
1.1.3 Spherical spreading 2
1.1.4 Seismic velocities 3
1.1.5 Wavefronts and ray-paths3
1.1.6 Reflection coefficients5
1.1.7 Transmission coefficients 7
1.1.8 The qV log and the basic seismic record 8
1.1.9 Mode conversion9
1.1.10 Surface waves 11
1.1.11 Ambient noise12
1.1.12 The objective of seismic recording technique 12
2 The manipulation of waveforms
2.1 Basic waveform concepts and definitions 14
2.1.1 Waveforms and operators 14
2.1.2 The sine wave 15
2.1.3 Bandwidths and octaves 16
2.1.4 The decibel scale 16
2.1.5 Linearity 17
2.2 The specification of waveforms 20
2.2.1 The time domain and the frequency domain20
2.2.2 The Fourier Series 20
2.2.3 Line spectra 22
2.2.4 The Fourier Integral 23
2.2.5 The continuous amplitude spectrum25
2.2.6 The continuous phase spectrum27
2.3 Linear operators and convolution 31
2.3.1 Linear operators 31
2.3.2 Frequency resppnse 31
2.3.3 The criterion of perfect fidelity 33
2.3.4 A typical example 33
2.3.5 The spike 34
2.3.6 The impulse-response 35
2.3.7 Superposition 36
2.3.8 Convolution 37
2.3.9 The complete Fourier scheme 39
2.3.10 Differentiation 40
2.3.11 Integration 43
2.3.12 Minimum-phase operators 45
3 The seismic reflection technique
3.1 The seismic signal 49
3.1.1 Introduction 49
3.1.2 The broad physical picture 49
3.1.3 Near-source effects 54
3.1.4 Effects in the body of the earth 56
3.1.5 The effect of reflections 62
3.1.6 Some numbers 67
3.2 Noise and surface waves 70
3.2.1 Wanted and unwanted signals 70
3.2.2 Ambient seismic noise 71
3.2.3 Surface waves 72
3.2.4 Man-made seismic noise 74
3.2.5 Source-generated seismic noise 75
3.2.6 Power-line interference 77
3.2.7 Electrical storms 77
3.2.8 Instrument noise 77
3.3 The field arrangement 78
3.3.1 The basic arrangement, and its dimensions 78
3.3.2 The spread 80
3.3.3 How many arrays? 81
3.3.4 Continuous cover 83
3.3.5 The arrangement for common-depth-point stacking 84
3.3.6 Variations 85
3.4 The seismic reflection record 86
3.5 The complete seismic chain 94
3.5.1 Source to detectors 94
3.5.2 Detectors to amplifiers 95
3.5.3 The amplifiers 96
3.5.4 The visual monitor 99
3.5.5 The recording system 101
3.5.6 Central processing 101
3.5.7 Variations 102
4 Desirable instrument characteristics
4.1 The easy ones 105
4.1.1 Record duration 105
4.1.2 Timing accuracy 105
4.1.3 Amplitude-frequency response 106
4.1.4 Phase-frequency response 107
4.1.5 Duplication 108
4.1.6 Physical characteristics 110
4.2 The problem of non-linearity 110
4.2.1 Introduction 110
4.2.2 Even and odd harmonics 111
4.2.3 Measurement of distortion 112
4.2.4 Points to watch 113
4.2.5 The problem of setting a tolerance 114
4.3 The problem of system noise 117
4.3.1 The concept of dynamic range 117
4.3.2 The characteristics of noise 119
4.3.3 Sources of system noise 123
4.3.4 The problem, and its solution 125
4.3.5 The relevance of filtering 130
4.4 Two illustrative specifications 132
4.4.1 A general-purpose equipment 132
4.4.2 A sign-bit system 137
Appendix
1.1 The International System of Units 140
1.2 Decibel conversion table 142
1.3 The phase-frequency response of minimum-phase operators 143
1.4 The Vibroseis system 144
Bibliography to Volume 1148
Index 151