Ground Motion Seismology

This book explains the physics behind seismic ground motions and seismic waves to graduate and upper undergraduate students as well as to professionals. Both seismic ground motions and seismic waves are terms for "shaking" due to earthquakes, but it is common that shaking in the near-field of an earthquake source is called seismic ground motion and in the far-field is called seismic waves. Seismic ground motion is often described by the tensor formula based on the representation theorem, but in this book explicit formulation is emphasized beginning with Augustus Edward Hough Love (1863 - 1940). The book also explains in depth the equations and methods used for analysis and computation of shaking close to an earthquake source. In addition, it provides in detail information and knowledge related to teleseismic body waves, which are frequently used in the analysis of the source of an earthquake.

Auteur

Kazuki Koketsu is a professor of applied seismology at the Earthquake Research Institute, The University of Tokyo, where he received his M.Sc. and Ph.D. in geophysics. He has held the positions of research associate and associate professor at the Earthquake Research Institute, The University of Tokyo, and visiting fellow at the Research School of Earth Sciences of the Australian National University. His selected papers include Koketsu, K. and M. Kikuchi, Propagation of seismic ground motion in the Kanto basin, Japan, Science 288, 1237-1239 (2000); Yokota, Y. and K. Koketsu, A very long-term transient event preceding the 2011 Tohoku earthquake, Nature Communications 6, doi:10.1038/ncomms6934 (2015); and Koketsu, K. et al., Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal, earthquake, Scientific Reports 6, doi:10.1038/srep28536 (2016).

He is a member of the Subcommittee for Evaluations of Strong Ground Motions, Ministry of Education, Culture, Sports, Science and Technology of Japan; the Committee of Earthquake Insurance, Ministry of Finance of Japan; a representative of the Seismological Society of Japan; and the recipient of the 2016 Paper Award of the Japan Association for Earthquake Engineering. He was an associate editor of the Journal of Seismology (Springer) between 2005 and 2012.

Contenu

1 Earthquakes and Ground Motion

1.1 Definition of Ground Motion

1.2 Ground Motion and Seismic Waves

1.2.1 Elastic Strain

1.2.2 Balance of Stress

1.2.3 Constitutive Law and Equation of Motion

1.2.4 Wave Equation and Seismic Wave

1.2.5 Wavefronts and Rays

1.2.6 Anelasticity

1.3 Principles of Ground Motion

1.3.1 Principle of Superposition

1.3.2 Reciprocity Theorem

1.3.3 Representation Theorem

Problems

References

2 The Effect of Earthquake Source

2.1 Representation of Earthquake Source

2.1.1 Discovery of Earthquake Source

2.1.2 Representation of Source Fault

2.1.3 Ground Motion by Point Force

2.1.4 Ground Motion by Point Source 2.1.5 Potential Representation

2.2 Cylindrical Wave Expansion

2.2.1 Vertical Strike Slip Fault

2.2.2 Inclined Strike Slip Fault

2.2.3 Vertical Dip Slip Fault

2.2.4 Inclined Dip Slip Fault

2.2.5 Extension to Arbitrary Fault Slip

2.3 Analysis of the Earthquake Source

2.3.1 Hypocenter Determination

2.3.2 Radiation Pattern and Fault Plane Solution

2.3.3 Moment Tensor

2.3.4 CMT Inversion

2.3.5 Ground Motion from a Finite Fault

2.3.6 Source Processes and Source Inversion

2.3.7 Stress Drop and Slip Rate Function

2.3.8 Directivity Effect

Problems

References

3 The Effect of Propagation

3.1 Propagation in 1-D Media

3.1.1 1-D Velocity Structure

3.1.2 SH wave

3.1.3 P wave and SV wave

3.1.4 Haskell matrix

3.1.5 Reflection/Transmission Matrix I

3.1.6 Reflection/Transmission Matrix II

3.1.7 Wavenumber Integration (Approximate)

3.1.8 Wavenumber Integration (Numerical)

3.1.9 Surface Wave (Love Wave)

3.1.10 Surface Wave (Rayleigh Wave)

3.1.11 Teleseismic Body Wave

3.1.12 Crustal Deformation

3.2 Propagation in 3-D Velocity Structures

3.2.1 3-D Velocity Structure

3.2.2 Ray Theory

3.2.3 Ray Tracing

3.2.4 Finite Difference Method

3.2.5 Finite Element Method

3.2.6 Aki-Larner Method

3.3 Analysis of Propagation

3.3.1 Long-Period Ground Motion

3.3.2 Microtremors

3.3.3 Seismic Interferometry

3.3.4 Seismic Tomography

Problems

References

4 Observation and Processing

4.1 Seismographs

4.1.1 Instrumentation of Seismographs

4.1.2 Strong Motion Seismographs

4.1.3 Electromagnetic Seismographs

4.1.4 Servo Mechanisms

4.2 Spectral Processing

4.2.1 A/D Conversion

4.2.2 Fourier Transform

4.2.3 Discrete Fourier Transform

4.2.4 FFT

4.3 Filtering

4.3.1 Filters and Windows

4.3.2 Low-Pass Filters

4.3.3 High-Pass and Band-Pass Filters

4.4 Least-Squares Method

4.4.1 Computation in Least-Squares Method

4.4.2 Constraints in Least-Squares Method

Problems

References

Appendix

A.1 Magnitude

A.1.1 Definition of Magnitude

A.1.2 Recent Magnitudes

A.2 Seismic Intensity

A.2.1 Characteristics of Seismic Intensity

A.2.2 Sensory Seismic Intensity

A.2.3 Instrumental Seismic Intensity

References

Index