Routine Data Processing in Earthquake Seismology: With Sample Data, Exercises and Software

by Jens Havskov, Lars Ottemoller

Overview

The purpose of this book is to get a practical understanding of the most common processing techniques in earthquake seismology. The book deals with manual methods and computer assisted methods. Each topic will be introduced with the basic theory followed by practical examples and exercises. There are manual exercises entirely based on the printed material of the book, as well as computer exercises based on public domain software. Most exercises are computer based. The software used, as well as all test data are available from http://extras.springer.com.

This book is intended for everyone processing earthquake data, both in the observatory routine and in connection with research. Using the exercises, the book can also be used as a basis for university courses in earthquake processing.

Since the main emphasis is on processing, the theory will only be dealt with to the extent needed to understand the processing steps, however references will be given to where more extensive explanations can be found.

Includes:
• Exercises
• Test data
• Public domain software (SEISAN)
available from http://extras.springer.com

Product Details

ISBN-13:	9789400790780
Publisher:	Springer Netherlands
Publication date:	11/14/2014
Edition description:	2010
Pages:	347
Product dimensions:	6.10(w) x 9.25(h) x 0.03(d)

Table of Contents

1 Introduction 1

1.1 Earthquakes 2

1.2 Recording Seismic Events and Picking Phases 6

1.3 Locating Earthquakes 9

1.4 Magnitude 10

1.5 Fault Plane Solution 11

1.6 Further Data Analysis 12

1.7 Software 13

2 Earth Structure and Seismic Phases 15

2.1 Earth Structure 15

2.2 Seismic Rays 18

2.3 Seismic Phases 21

2.4 Travel Times 28

2.5 Seismic Phases at Different Distances 33

2.6 Determination of Structure 45

2.7 Excercises 48

3 Instruments and Waveform Data 53

3.1 Seismic Sensors 53

3.2 Seismic Recorders 58

3.3 Correction for Instrument Response 61

3.3.1 How to Store the Response Information 65

3.3.2 Response in Practice 66

3.3.3 Using Response 67

3.3.4 How to Make Response Files 67

3.4 Waveform Formats 68

3.4.1 GSE 69

3.4.2 SEED 70

3.4.3 SAC 71

3.4.4 SEISAN 71

3.4.5 CSS 72

3.4.6 Common Points to Consider with Waveform Formats 72

3.4.7 Format to Use 76

3.5 Seismic Noise 76

3.6 Exercises 80

4 Signal Processing 83

4.1 Filtering 83

4.2 Spectral Analysis and Instrument Correction 86

4.3 Reading Seismic Phases 91

4.3.1 First Onset 91

4.3.2 Filtering and Phase Shift 91

4.3.3 Plotting Resolution 93

4.4 Correlation 94

4.5 Particle Motion and Component Rotation 94

4.6 Resampling 98

4.7 Software 99

4.8 Exercises 99

5 Location 101

5.1 Single Station Location 103

5.2 Multiple Station Location 107

5.3 Computer Implementation 110

5.3.1 Grid Search 110

5.3.2 Location by Iterative Methods 112

5.3.3 Example of Location in a Homogeneous Model 115

5.4 Error Quantification and Statistics 116

5.4.1 Example of Error Calculation 118

5.5 Relative Location Methods 120

5.5.1 Master Event Technique 120

5.5.2 Joint Hypocenter Location 122

5.5.3 Double Difference Earthquake Location 123

5.6 Practical Considerations in Earthquake Locations 124

5.6.1 Phases 126

5.6.2 Hypocentral Depth 127

5.6.3 Starting Location 134

5.6.4 Identification of P for Teleseismic Events 138

5.6.5 Outliers and Weighting Schemes 138

5.6.6 Timing Errors 139

5.6.7 Example of Outlier and Timing ProbleM_s 139

5.7 Software 143

5.8 Exercises 145

6 Magnitude 151

6.1 Amplitude and Period Measurements 153

6.2 Local Magnitude M_L 154

6.3 Coda Magnitude M_c 160

6.4 Body Wave Magnitude m_b 164

6.5 Broad Band Body Wave Magnitude m_B 169

6.6 Surface Wave Magnitude M_s 171

6.7 Broad Band Surface Wave Magnitude M_s 175

6.8 L_g-Wave Magnitude 178

6.9 Moment Magnitude M_w 178

6.10 Energy Magnitude M_e 179

6.11 Comparison of Magnitude Scales 180

6.12 Summary 183

6.13 Average Magnitude and Station Corrections 184

6.14 Adjusting Magnitude Scales to Local or Regional Conditions 185

6.14.1 Select a Scale from Another Region 185

6.14.2 Derive M_L Scale 186

6.14.3 Derive M_c Scale 187

6.14.4 Determine Local Attenuation to Calculate M_w 188

6.15 Exercises 188

7 Focal Mechanism and Seismogram Modeling 193

7.1 Fault geometry 194

7.2 Source Radiation 195

7.3 Fault Plane Solution in Practice 198

7.4 Obtaining Polarity 206

7.5 Fault Plane Solution Using Local Data and Polarity 208

7.6 Composite Fault Plane Solution 209

7.7 Fault Plane Solution Using Global Data 210

7.8 Fault Plane Solution Using Amplitudes 212

7.8.1 Using Amplitude Ratios 214

7.8.2 Example of Using Amplitude Ratios for a Distant Earthquake 216

7.8.3 Using Spectral Amplitudes 219

7.9 Moment Tensor 222

7.10 Moment Tensor Inversion 227

7.10.1 Moment Tensor Inversion at Local and Regional Distance 229

7.10.2 Global Distance 233

7.11 Seismogram Modeling 235

7.11.1 Ray Method 236

7.11.2 Approximation to Complete SeismograMs 236

7.11.3 Global Case of Using the Ray Method 236

7.11.4 The Source Time Function 237

7.11.5 Local Case of Using the Ray Method 238

7.11.6 Complete Seismogram 239

7.12 Software 240

7.13 Exercises 241

8 Spectral Analysis 245

8.1 Attenuation 245

8.2 Seismic Source Model 248

8.3 Geometrical Spreading 251

8.3.1 Local and Regional Distances 251

8.3.2 Teleseismic Distances 253

8.4 Self Similarity and Seismic Source Spectra 255

8.5 Spectral Analysis at Local and Regional Distances 257

8.6 Spectral Analysis at Teleseismic Distances 262

8.6.1 Attenuation 262

8.6.2 Geometrical Spreading 263

8.7 Determination of Q 265

8.7.1 Determine k 265

8.7.2 Q and k from Spectral Modeling 267

8.7.3 Coda Q 268

8.7.4 Two Station Methods for Q-Determination 273

8.7.5 Multiple Station Method for Q-Determination 276

8.8 Soil Amplification 278

8.9 Exercises 280

9 Array Processing 283

9.1 Basic Array Parameters 283

9.1.1 Example of Calculating p from a Three Station Array 286

9.1.2 Using a Seismic Network as an Array 287

9.2 Beam Forming 288

9.3 Frequency-Wavenumber Analysis (fk) 289

9.4 Array Response 290

9.5 Processing Software 292

9.5.1 Manual Processing 292

9.5.2 FK Processing 293

9.6 Using Array Measurements for Identifying Phases 294

9.7 Exercises 295

10 Operation 299

10.1 Data and Data Storage 299

10.2 Routine Processing 303

10.2.1 Screening of Detections 303

10.2.2 Event Classification 304

10.2.3 Analysis 304

10.2.4 Epi and Hypocenter Maps 307

10.2.5 Felt Earthquakes 308

10.2.6 Quality Control 309

10.2.7 Seismic Bulletin 314

10.3 Data Exchange 314

10.4 Earthquake Statistics 318

10.5 Software 320

10.5.1 Processing Systems for Routine Operation 321

10.5.2 Mapping Software 323

10.6 Exercises 324

References 327

Index 339

Editorial Reviews

From the reviews:

“A book useful for training students in basic analysis skills … . The book has a clear target audience: the routine analysts who manually process seismic network data. … The approach could be characterized as suitably utilitarian. A strength of the book is the assumption that operators will use one of the existing seismic data analysis systems. The authors have a fairly wide knowledge of present systems and data recording formats and present some useful critiques of them.” (George Helffrich, Geological Magazine, February, 2011)

“The book presents a very good overview of the routine data processing in earthquake seismology. It should find its place at every seismological data center, serving as a general guide, a reminder of the issues that are not part of the data center’s everyday routine and an overview for the data center’s beginners or for visitors.”­­­ (Pawel Wiejacz, Pure and Applied Geophysics, Vol. 168, 2011)

From the Publisher