An Introduction to Seismology, Earthquakes, and Earth Structure

by Stein, Seth; Wysession, Michael

• ISBN13: 9780865420786
• ISBN10: 0865420785
• Edition: 1st
• Format: Paperback
• Copyright: 1991-01-16
• Publisher: Wiley-Blackwell

Summary

An Introduction to Seismology, Earthquakes and Earth Structures is an introduction to seismology and its role in the earth sciences, and is written for advanced undergraduate and beginning graduate students.The fundamentals of seismic wave propagation are developed using a physical approach and then applied to show how refraction, reflection, and teleseismic techniques are used to study the structure and thus the composition and evolution of the earth. The book shows how seismic waves are used to study earthquakes and are integrated with other data to investigate the plate tectonic processes that cause earthquakes. Figures, examples, problems, and computer exercises teach students about seismology in a creative and intuitive manner. Necessary mathematical tools including vector and tensor analysis, matrix algebra, Fourier analysis, statistics of errors, signal processing, and data inversion are introduced with many relevant examples. The text also addresses the fundamentals of seismometry and applications of seismology to societal issues. Special attention is paid to help students visualize connections between different topics and view seismology as an integrated science.An Introduction to Seismology, Earthquakes, and Earth Structure gives an excellent overview for students of geophysics and tectonics, and provides a strong foundation for further studies in seismology. Multidisciplinary examples throughout the text - catering to students in varied disciplines (geology, mineralogy, petrology, physics, etc.). Most up to date book on the market - includes recent seismic events such as the 1999 Earthquakes in Turkey, Greece, and Taiwan). Chapter outlines - each chapter begins with an outline and a list of learning objectives to help students focus and study. Essential math review - an entire section reviews the essential math needed to understand seismology. This can be covered in class or left to students to review as needed. End of chapter problem sets - homework problems that cover the material presented in the chapter. Solutions to all odd numbered problem sets are listed in the back so that students can track their progress. Extensive References - classic references and more current references are listed at the end of each chapter. A set of instructor's resources containing downloadable versions of all the figures in the book, errata and answers to homework problems is available at: http://levee.wustl.edu/seismology/book/. Also available on this website are PowerPoint lecture slides corresponding to the first 5 chapters of the book.

Author Biography

Seth Stein is Professor of Geological Sciences at Northwestern University. He has received the James B Macelwane Medal of the American Geophysical Union, been elected a Fellow of the American Geophysical Union and Geological Society of America, and named to the Institute for Scientific Information Highly Cited Researchers list. He served as Scientific Director of the University Navstar Consortium and on the Incorporated Research Institutions for Seismology's Executive Committee, and started Northwestern's Environmental Science program.

Michael Wysession is an Associate Professor in the Department of Earth and Planetary Sciences at Washington University. He is the recipient of the Packard Foundation and NSF Presidential Faculty Fellowships for his research into the structure of the Earth's deep interior.

Table of Contents

Preface	ix
Acknowledgments	xi
Introduction	1	(28)
Introduction	1	(8)
Overview	1	(4)
Models in seismology	5	(4)
Seismology and society	9	(20)
Seismic hazards and risks	11	(3)
Engineering seismology and earthquake engineering	14	(4)
Highways, bridges, dams, and pipelines	18	(1)
Tsunamis, landslides, and soil liquefaction	19	(1)
Earthquake forecasting	20	(4)
Earthquake prediction	24	(2)
Real-time warnings	26	(1)
Nuclear monitoring and treaty verification	26	(2)
Further reading	28	(1)
Basic Seismological Theory	29	(90)
Introduction	29	(1)
Waves on a string	29	(9)
Theory	29	(2)
Harmonic wave solution	31	(1)
Reflection and transmission	32	(3)
Energy in a harmonic wave	35	(1)
Normal modes of a string	36	(2)
Stress and strain	38	(15)
Introduction	38	(1)
Stress	39	(2)
Stress as a tensor	41	(1)
Principal stresses	42	(1)
Maximum shear stress and faulting	43	(2)
Deviatoric stresses	45	(1)
Equation of motion	46	(1)
Strain	47	(1)
Constitutive equations	48	(3)
Boundary conditions	51	(1)
Strain energy	52	(1)
Seismic waves	53	(9)
The seismic wave equation	53	(1)
Plane waves	54	(1)
Spherical waves	55	(1)
P and S waves	56	(5)
Energy in a plane wave	61	(1)
Snell's law	62	(13)
The layered medium approximation	62	(1)
Plane wave potentials for a layered medium	63	(2)
Angle of incidence and apparent velocity	65	(1)
Snell's law	66	(1)
Critical angle	67	(1)
Snell's law for SH waves	68	(1)
Ray parameter and slowness	69	(1)
Waveguides	70	(1)
Fermat's principle and geometric ray theory	70	(2)
Huygens' principle and diffraction	72	(3)
Plane wave reflection and transmission coefficients	75	(11)
Introduction	75	(1)
SH wave reflection and transmission coefficients	76	(1)
Energy flux for reflected and transmitted SH waves	77	(1)
Postcritical SH waves	78	(1)
P-SV waves at a free surface	79	(2)
Solid-solid and solid-liquid interfaces	81	(4)
Examples	85	(1)
Surface waves	86	(7)
Introduction	86	(1)
Rayleigh waves in a homogeneous halfspace	87	(3)
Love waves in a layer over a halfspace	90	(1)
Love wave dispersion	91	(2)
Dispersion	93	(8)
Phase and group velocity	93	(1)
Dispersive signals	94	(2)
Surface wave dispersion studies	96	(3)
Tsunami dispersion	99	(2)
Normal modes of the earth	101	(18)
Motivation	101	(1)
Modes of a sphere	101	(2)
Spherical harmonics	103	(1)
Torsional modes	104	(2)
Spheroidal modes	106	(1)
Modes and propagating waves	106	(4)
Observing normal modes	110	(1)
Normal mode synthetic seismograms	111	(1)
Mode attenuation, splitting, and coupling	111	(4)
Further reading	115	(1)
Problems	116	(3)
Seismology and Earth Structure	119	(96)
Introduction	119	(1)
Refraction seismology	120	(14)
Flat layer method	120	(3)
Dipping layer method	123	(3)
Advanced analysis methods	126	(2)
Crustal structure	128	(4)
Rocks and minerals	132	(2)
Reflection seismology	134	(23)
Travel time curves for reflections	134	(3)
Intercept-slowness formulation for travel times	137	(3)
Multichannel data geometry	140	(1)
Common midpoint stacking	141	(4)
Signal enhancement	145	(3)
Deconvolution	148	(4)
Migration	152	(4)
Data processing sequence	156	(1)
Seismic waves in a spherical earth	157	(5)
Ray paths and travel times	157	(2)
Velocity distributions	159	(2)
Travel time curve inversion	161	(1)
Body wave travel time studies	162	(15)
Body wave phases	163	(3)
Core phases	166	(3)
Upper mantle structure	169	(2)
Lower mantle structure	171	(3)
Visualizing body waves	174	(3)
Anisotropic earth structure	177	(8)
General considerations	177	(1)
Transverse isotropy and azimuthal anisotropy	177	(2)
Anisotropy of minerals and rocks	179	(1)
Anisotropy of composite structures	180	(1)
Anisotropy in the lithosphere and the asthenosphere	180	(2)
Anisotropy in the mantle and the core	182	(3)
Attenuation and anelasticity	185	(13)
Wave attenuation	185	(2)
Geometric spreading	187	(1)
Multipathing	187	(2)
Scattering	189	(1)
Intrinsic attenuation	190	(2)
Quality factor, Q	192	(1)
Spectral resonance peaks	193	(1)
Physical dispersion due to anelasticity	194	(2)
Physical models for anelasticity	196	(1)
Q from crust to inner core	197	(1)
Composition of the mantle and the core	198	(17)
Density within the earth	199	(4)
Temperature in the earth	203	(1)
Composition of the mantle	204	(4)
Composition of D''	208	(1)
Composition of the core	209	(1)
Seismology and planetary evolution	210	(2)
Further reading	212	(1)
Problems	212	(3)
Earthquakes	215	(71)
Introduction	215	(2)
Focal mechanisms	217	(12)
Fault geometry	217	(2)
First motions	219	(1)
Body wave radiation patterns	220	(2)
Stereographic fault plane representation	222	(6)
Analytical representation of fault geometry	228	(1)
Waveform modeling	229	(10)
Basic model	229	(1)
Source time function	230	(1)
Body wave modeling	231	(4)
Surface wave focal mechanisms	235	(4)
Once and future earthquakes	239	(1)
Moment tensors	239	(12)
Equivalent forces	239	(1)
Single forces	240	(1)
Force couples	241	(1)
Double couples	242	(1)
Earthquake moment tensors	242	(3)
Isotropic and CLVD moment tensors	245	(1)
Moment tensor inversion	246	(3)
Interpretation of moment tensors	249	(2)
Earthquake geodesy	251	(12)
Measuring ground deformation	251	(3)
Coseismic deformation	254	(2)
Joint geodetic and seismological earthquake studies	256	(3)
Interseismic deformation and the seismic cycle	259	(4)
Source parameters	263	(11)
Magnitudes and moment	263	(3)
Source spectra and scaling laws	266	(3)
Stress drop and earthquake energy	269	(5)
Earthquake statistics	274	(12)
Frequency--magnitude relations	274	(3)
Aftershocks	277	(1)
Earthquake probabilities	278	(4)
Further reading	282	(1)
Problems	282	(4)
Seismology and Plate Tectonics	286	(83)
Introduction	286	(4)
Plate kinematics	290	(8)
Relative plate motions	290	(3)
Global plate motions	293	(2)
Space-based geodesy	295	(1)
Absolute plate motions	296	(2)
Spreading centers	298	(9)
Geometry of ridges and transforms	298	(1)
Evolution of the oceanic lithosphere	299	(6)
Ridge and transform earthquakes and processes	305	(2)
Subduction zones	307	(19)
Thermal models of subduction	308	(4)
Earthquakes in subducting slabs	312	(9)
Interplate trench earthquakes	321	(5)
Oceanic intraplate earthquakes and tectonics	326	(7)
Locations of oceanic intraplate seismicity	326	(2)
Forces and stresses in the oceanic lithosphere	328	(3)
Constraints on mantle viscosity	331	(2)
Continental earthquakes and tectonics	333	(13)
Continental plate boundary zones	334	(5)
Seismic, aseismic, transient, and permanent deformation	339	(3)
Continental intraplate earthquakes	342	(4)
Faulting and deformation in the earth	346	(23)
Rheology	346	(2)
Rock fracture and friction	348	(7)
Ductile flow	355	(2)
Strength of the lithosphere	357	(2)
Earthquakes and rock friction	359	(5)
Earthquakes and regional deformation	364	(2)
Further reading	366	(1)
Problems	367	(2)
Seismograms as Signals	369	(46)
Introduction	369	(1)
Fourier analysis	369	(8)
Fourier series	369	(2)
Complex Fourier series	371	(1)
Fourier transforms	372	(2)
Properties of Fourier transforms	374	(1)
Delta functions	375	(2)
Linear systems	377	(8)
Basic model	377	(2)
Convolution and deconvolution modeling	379	(1)
Finite length signals	380	(3)
Correlation	383	(2)
Discrete time series and transforms	385	(6)
Sampling of continuous data	385	(2)
The discrete Fourier transform	387	(2)
Properties of DFTs	389	(1)
The fast Fourier transform (FFT)	389	(1)
Digital convolution	390	(1)
Stacking	391	(7)
Random errors	392	(3)
Stacking examples	395	(3)
Seismometers and seismological networks	398	(17)
Introduction	398	(1)
The damped harmonic oscillator	398	(2)
Earth noise	400	(1)
Seismometers and seismographs	400	(5)
Digital recording	405	(2)
Types of networks	407	(1)
Global networks	407	(2)
Arrays	409	(1)
Regional networks	410	(2)
Further reading	412	(1)
Problems	412	(3)
Inverse Problems	415	(28)
Introduction	415	(1)
Earthquake location	416	(8)
Theory	416	(3)
Earthquake location for a homogeneous medium	419	(1)
Errors	420	(2)
Earthquake location for more complex geometries	422	(2)
Travel time tomography	424	(10)
Theory	424	(2)
Generalized inverse	426	(1)
Properties of the generalized inverse solution	427	(2)
Variants of the solution	429	(1)
Examples	430	(4)
Stratified earth structure	434	(5)
Earth structure from normal modes	434	(2)
Parameter and data space inversions	436	(1)
Features of the solutions	437	(2)
Inverting for plate motions	439	(4)
Method	439	(1)
Testing the results with X2 and F-ration tests	440	(1)
Further reading	441	(1)
Problems	442	(1)
Appendix: Mathematical and Computational Background	443	(33)
A.1 Introduction	443	(1)
A.2 Complex numbers	443	(2)
A.3 Scalars and vectors	445	(5)
A.3.1 Definitions	445	(1)
A.3.2 Elementary vector operations	446	(1)
A.3.3 Scalar products	446	(1)
A.3.4 Vector products	447	(1)
A.3.5 Index notation	448	(1)
A.3.6 Vector spaces	449	(1)
A.4 Matrix algebra	450	(4)
A.4.1 Definitions	450	(1)
A.4.2 Determinant	451	(1)
A.4.3 Inverse	452	(1)
A.4.4 Systems of linear equations	452	(1)
A.4.5 Solving systems of equations on a computer	453	(1)
A.5 Vector transformations	454	(4)
A.5.1 Coordinate transformations	455	(1)
A.5.2 Eigenvalues and eigenvectors	456	(2)
A.5.3 Symmetric matrix eigenvalues, eigenvectors, diagonalization, and decomposition	458	(1)
A.6 Vector calculus	458	(4)
A.6.1 Scalar and vector fields	458	(1)
A.6.2 Gradient	459	(1)
A.6.3 Divergence	459	(1)
A.6.4 Curl	460	(1)
A.6.5 Laplacian	461	(1)
A.7 Spherical coordinates	462	(4)
A.7.1 The spherical coordinate system	462	(1)
A.7.2 Distance and azimuth	463	(2)
A.7.3 Choice of axes	465	(1)
A.7.4 Vector operators in spherical coordinates	465	(1)
A.8 Scientific programming	466	(10)
A.8.1 Example: synthetic seismogram calculation	466	(3)
A.8.2 Programming style	469	(1)
A.8.3 Representation of numbers	470	(1)
A.8.4 A few pitfalls	471	(1)
A.8.5 Some philosophical points	472	(1)
Further reading	473	(1)
Problems	473	(3)
References	476	(10)
Solutions to selected odd-numbered problems	486	(3)
Index	489