SURFACE WAVEANALYSIS FOR NEARSURFACE APPLICATIONS

It’s not what you look at that matters, it’s what you see.

Henry David Thoreau

SURFACE WAVEANALYSIS FOR NEARSURFACE APPLICATIONS

GIANCARLO DAL MORO

Institute of Rock Structure and Mechanics Academy

of Sciences of the Czech Republic, Prague,

Czech Republic

&

Eliosoft, Udine, Italy

AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD

PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO

Elsevier

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Library of Congress Cataloging-in-Publication Data

Dal Moro, Giancarlo, 1969-

Surface wave analysis for near surface applications / Giancarlo Dal Moro.

pages cm

Includes bibliographical references and index.

ISBN 978-0-12-800770-9

1. Surface waves (Seismology) 2. Seismology. I. Title.

QE538.5.D35 2015

551.22028’7–dc23

2014035516

British Library Cataloguing-in-Publication Data

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

ISBN: 978-0-12-800770-9

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CONTENTS

Preface vii

1. Introducing Surface Waves 1

1.1 A Brief Introduction 1

1.2 Lord Rayleigh and Prof. Love 1

1.3 Dispersion for Dummies 5

1.4 Dispersion, Velocity Spectra, and Dispersion Curves 8

1.5 Attenuation in Short 14

1.6 Surface Waves, Geology, Nonuniqueness, and Anisotropies 18

2. Data Acquisition 23

2.1 Introduction 23

2.2 Active Methodologies 25

2.3 Passive Methodologies 36

2.4 Few Final Remarks 41

3. Understanding Surface-Wave Phenomenology 43

3.1 Introducing the Problem 43

3.2 More about Modes and Components 49

3.3 About Passive Methods 57

3.4 Few Final Remarks 61

4. Horizontal-to-Vertical Spectral Ratio 65

4.1 Introduction 65

4.2 Data Acquisition and HVSR Computation 66

4.3 Some Problems 72

5. Inversion and Joint Inversion 87

5.1 Introduction 87

5.2 Misfit, Inversion, and Modeling: Concepts and Misconcepts 88

5.3 Local Minima and Nonuniqueness of the Solution 93

5.4 Joint Analysis 96

v

6. Full Velocity Spectrum Inversion and Other Unconventional Approaches 103

6.1 Introduction 103

6.2 Full Waveform and Full Velocity Spectrum Inversions 107

7. Some Final Notes 113

7.1 The Adopted Perspective 113

7.2 A Brief Miscellanea on Modes and Shear-Wave Velocities 114

7.3 Survey Planning and Result Evaluation 121

7.4 Summarizing Few Final Recommendations 127

AppendixdA Collection of Commented Case Studies 131

CASE STUDY 1: A Simple ZVF Analysis for Geotechnical Purposes 133

CASE STUDY 2: A Simple (but Educational) Case Study 139

CASE STUDY 3: Inverse Dispersion by the Book 149

CASE STUDY 4: When the Joint Analysis of Love and Rayleigh Waves Is Necessary 153

CASE STUDY 5: Joint Analysis of Rayleigh-Wave Dispersion and P-Wave Refraction 159

CASE STUDY 6: A Comprehensive Survey in the Swiss Alps 163

CASE STUDY 7: Joint Analysis of Rayleigh and Love Waves via Full Velocity Spectrum Analysis 171

CASE STUDY 8: A Civil Engineering Job 177

CASE STUDY 9: A Landslide Area 185

CASE STUDY 10: Back to the Swiss Alps 189

CASE STUDY 11: Modes and Components (A Very Tricky Site) 197

CASE STUDY 12: Analyzing Phase and Group Velocities Jointly with Horizontal-to-Vertical Spectral Ratio 205

CASE STUDY 13: Some Focus on Horizontal-to-Vertical Spectral Ratio Computation 211

CASE STUDY 14: Surface Waves on the Moon 219

References 227

Index 235

vi Contents