Imaging, Modeling and Assimilation in Seismology (eBook)

lt;!doctype html public "-//w3c//dtd html 4.0 transitional//en">

Edited by Yong-Gang Li, University of Southern California, Los Angeles, USA.

Imaging, Modeling and Assimilation in Seismology: An Overview 11
References 21
Chapter 1 Full-Wave Seismic Data Assimilation: A Unified Methodology for Seismic Waveform Inversion 29
1.1 Introduction 29
1.2 Generalized Inverse 31
1.2.1 Prior Probability Densities 32
1.2.2 Bayes’ Theorem 35
1.2.3 Euler-Lagrange Equations 36
1.3 Data Functionals 41
1.3.1 Differential Waveforms 42
1.3.2 Cross-correlation Measurements 43
1.3.3 Generalized Seismological Data Functionals (GSDF) 44
1.4 The Adjoint Method 48
1.4.1 An Example of Adjoint Travel-Time Tomography 49
1.4.2 Review of Some Recent Adjoint Waveform Tomography 51
1.5 The Scattering-Integral (SI) Method 52
1.5.1 Full-Wave Tomography Based on SI 54
1.5.2 Earthquake Source Parameter Inversion Based on SI 56
1.6 Discussion 64
1.6.1 Computational Challenges 65
1.6.2 Nonlinearity 67
1.7 Summary 68
References 69
Chapter 2 One-Return Propagators and the Applications in Modeling and Imaging 75
2.1 Introduction 76
2.2 Primary-Only Modeling and One-Return Approximation 77
2.3 Elastic One-Return Modeling 82
2.3.1 Local Born Approximation 83
2.3.2 The Thin Slab Approximation 85
2.3.3 Small-Angle Approximation and the Screen Propagator 87
2.3.4 Numerical Implementation 90
2.3.5 Elastic, Acoustic and Scalar Cases 91
2.4 Applications of One-Return Propagators in Modeling, Imaging and Inversion 91
2.4.1 Applications to Modeling 91
2.4.2 One-Return Propagators Used in Migration Imaging 95
2.4.3 Calculate Finite-Frequency Sensitivity Kernels Used in Velocity Inversion 98
2.5 Other Development of One-Return Modeling 103
2.5.1 Super-Wide Angle One-Way Propagator 103
2.5.2 One-Way Boundary Element Method 105
2.6 Conclusion 109
References 110
Chapter 3 Fault-Zone Trapped Waves: High-Resolution Characterization of the Damage Zone of the Parkfield San Andreas Fault at Depth 117
3.1 Introduction 117
3.2 Fault-Zone Trapped Waves at the SAFOD Site 119
3.2.1 The SAFOD Surface Array 121
3.2.2 The SAFOD Borehole Seismographs 126
3.2.3 Finite-Difference Simulation of Fault-Zone Trapped Waves at SAFOD Site 134
3.3 Fault-Zone Trapped Waves at the Surface Array near Parkfield Town 142
3.4 Conclusion and Discussion 145
Acknowledgements 148
References 148
Appendix: Modeling Fault-Zone Trapped SH-Love Waves 153
Chapter 4 Fault-Zone Trapped Waves at a Dip Fault: Documentation of Rock Damage on the Thrusting Longmen-Shan Fault Ruptured in the 2008 M8 Wenchuan Earthquake 161
4.1 Geological Setting and Scientific Significance 162
4.2 Data and Results 164
4.2.1 Data Collection 164
4.2.2 Examples of Waveform Data 167
4.3 3-D Finite-Difference Investigations of Trapping Efficiency at the Dipping Fault 174
4.3.1 Effect of Fault-Zone Dip Angle 176
4.3.2 Effect of Epicentral Distance 179
4.3.3 Effect of Source Depth 181
4.3.4 Effect of Source away from Vertical and Dip Fault Zones 182
4.3.5 Effect of Fault-Zone Width and Velocity Reduction 185
4.4 3-D Finite-Difference Simulations of FZTWs at the South Longmen-Shan Fault 185
4.5 Fault Rock Co-Seismic Damage and Post-Mainshock Heal 190
4.6 Conclusion and Discussion 196
Acknowledgements 200
References 200
Appendix 206
Chapter 5 Ground-Motion Simulations with Dynamic Source Characterization and Parallel Computing 209
5.1 Introduction 209
5.2 The Spontaneous Rupture Model 210
5.3 EQdyna: An Explicit Finite Element Method for Simulating Spontaneous Rupture on Geometrically Complex Faults and Wave Propagation in Complex Geologic Structure 213
5.4 Two Examples of Ground-Motion Related Applications of EQdyna 216
5.4.1 Sensitivity of Physical Limits on Ground Motion on Yucca Mountain 216
5.4.2 Effects of Faulting Style Change on Ground Motion 219
5.5 Hybrid MPI/OpenMP Parallelization of EQdyna and Its Application to a Benchmark Problem 220
5.5.1 Element-size Dependence of Solutions 221
5.5.2 Computational Resource Requirements and Performance Analysis 225
5.6 Conclusions 225
Acknowledgements 226
References 226
Chapter 6 Load-Unload Response Ratio and Its New Progress 229
6.1 Introduction 229
6.2 The Status of Earthquake Prediction Using LURR 233
6.3 Peak Point of the LURR and Its Significance 234
6.4 Earthquake Cases in 2008–2009 236
6.5 Improving the Prediction of Magnitude M and T2-Application of Dimensional Method 237
6.5.1 Location 237
6.5.2 Magnitude 237
6.5.3 Occurrence time (T2) 241
6.6 Conclusions 242
Acknowledgements 242
References 242
Chapter 7 Discrete Element Method and Its Applications in Earthquake and Rock Fracture Modeling 245
7.1 Introduction 245
7.2 A Brief Introduction to the Esys_Particle 247
7.3 Theoretical and Algorithm Development 248
7.3.1 The Equations of Particle Motion 248
7.3.2 Contact Laws, Particle Interactions and Calculation of Forces and Torques 249
7.3.3 Calibration of the Model 252
7.3.4 Incorporation of Thermal and Hydrodynamic Effects 253
7.3.5 Parallel Algorithm 255
7.4 Some Numerical Results Obtained by Using the Esys-Particle 255
7.4.1 Earthquakes 255
7.4.2 Rock fracture 261
7.5 Coupling of Multiple Physics 264
7.5.1 Thermal-Mechanical Coupling 264
7.5.2 Hydro-Mechanical Coupling 265
7.5.3 Full Solid-Fluid Coupling 265
7.6 Discussion and Conclusions 266
Acknowledgements 268
References 268