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Author: Agustín Udías Vallina Publisher: Cambridge University Press ISBN: 1107040272 Category : Nature Languages : en Pages : 313
Book Description
An innovative new approach to studying earthquake source mechanisms, combining theory and observation, for graduate students, researchers and seismology professionals.
Author: Agustín Udías Vallina Publisher: Cambridge University Press ISBN: 1107040272 Category : Nature Languages : en Pages : 313
Book Description
An innovative new approach to studying earthquake source mechanisms, combining theory and observation, for graduate students, researchers and seismology professionals.
Author: B. V. Kostrov Publisher: Cambridge University Press ISBN: 9780521303453 Category : Mathematics Languages : en Pages : 308
Book Description
Kostrov and Das present a general theoretical model summarizing our current knowledge of fracture mechanics as applied to earthquakes and earthquake source processes. Part I explains continuum and fracture mechanics, providing the reader with some background and context. Part II continues with a discussion of the inverse problem of earthquake source theory and a description of the seismic moment tensor. Part III presents specific earthquake source models. Although data processing and acquisition techniques are discussed only in simplified form for illustrative purposes, the material in this book will aid in better orienting and developing these techniques. The aim of this book is to explore the phenomena underlying earthquake fracture and present a general theoretical model for earthquake source processes.
Author: D.E. James Publisher: Springer Science & Business Media ISBN: 0442243669 Category : Science Languages : en Pages : 1299
Book Description
Consisting of more than 150 articles written by leading experts, this authoritative reference encompasses the entire field of solid-earth geophysics. It describes in detail the state of current knowledge, including advanced instrumentation and techniques, and focuses on important areas of exploration geophysics. It also offers clear and complete coverage of seismology, geodesy, gravimetry, magnetotellurics and related areas in the adjacent disciplines of physics, geology, oceanography and space science.
Author: UDIAS Publisher: Birkhäuser ISBN: 3034886543 Category : Science Languages : en Pages : 212
Book Description
nesus, Armenia, and Georgia have largely profited from the experience acquired in the study of the large events of the early 1980s. The Mediterranean region is not only the site of shallow dispersed seismic activity, it is also the site of localized intermediate depth seismic activity, and of some rare deeper events. Active subduc tion is clearly at the origin of Greek intermediate depth seismicity, while the deep activity under Calabria and the Vrancea region in Romania is clearly related to downgoing slabs that have long remained active after the arrest of subduction. The origin of the intermediate and very deep seismicity below Spain is a considerably more complex problem. Several possible explanations of the intermediate depth activity to about 110 km have been proposed, but the origin of the deep (650 km) events studied by BURFORN et a1. remains a mystery since this is the only source of deep activity that is not related in an obvious way to a subduction zone. The problem of seismic source mechanism and seismotectonics cannot be completely separated from that of the mechanical origin of earthquakes. Recent work on this subject has revealed the intimate relation between fault geometry, as observed by field geologists, and the results of inversion of source process from seismic data in the far-field or in the near-field.
Author: Hussam Abdullah Busfar Publisher: ISBN: Category : Languages : en Pages : 156
Book Description
Determining the focal mechanism of an earthquake helps us to better characterize reservoirs, define faults, and understand the stress and strain regime. The objective of this thesis is to find the focal mechanism and depth of earthquakes. This objective is met using a full waveform modeling method in which we generate synthetic seismograms using a discrete wavenumber code to match the observed seismograms. We first calculate Green's functions given an initial estimate of the earthquake's hypocenter, the locations of the seismic recording stations, and the velocity model of the region for a series of depths with intervals of 1 km. Then, we calculate the moment tensor for 6840 different combinations of strikes, dips, and rakes for each of those depths. These are convolved with Green's function and with an assumed smooth ramp source time function to produce the different synthetic seismograms corresponding to the different strikes, dips, rakes, and depths. We use a grid search in order to find the synthetic seismogram, with the combination of depth, strike, dip, and rake, that best fits the observed seismogram. These parameters will be the focal mechanism solution of an earthquake. The whole procedure is repeated for a reduced number of recording stations in order to determine a minimum number of recording stations that is needed for a reliable source mechanism and depth solution. We tested the method using two earthquakes in Southern California. Their locations, depths, and source mechanisms were determined using data from a multitude of stations. Southern California Seismic Network's real-time solution of earthquake 9718013 puts the earthquake at a depth of 15.22 km. The moment tensor inversion method determines the depth of the earthquake to be 8 km with a strike, dip, and rake of 318, 33, -180, respectively. The same network determines the depth of earthquake 14408052 to be 7.3 km. The moment tensor solution determines the strike, dip, rake, and depth of earthquake 14408052 to be 162, 82, -167, and 5 km, respectively. In this study, we wanted to test our method using seismograms from a relatively few stations. We used five stations for each earthquake, then 3 stations for earthquake 9718013, and two stations for earthquake 14408052. When using five recording stations, the strike, dip, rake, and depth of earthquake 9718013 are 300, 60, -170, and 15 km, respectively. When using three recording stations for the same earthquake, the strike, dip, rake, and depth are 300, 60, -180, and 14 km, respectively. For earthquake 14408052, the strike, dip, rake, and depth are 160, 80, -170, and 7 km, respectively, when using five recording stations. The strike, dip, rake, and depth for this same earthquake are 160, 80, -160, and 8 km, respectively, when using only two stations. The results show that the ten best solutions for each earthquake are very similar, and identical in many cases, indicating that the method is robust and the solution is unique. This assures us that the full waveform modeling method is a fast and reliable way to find the focal mechanisms and depths of earthquakes using seismograms from a few stations when the velocity structure is known.
Author: National Research Council Publisher: National Academies Press ISBN: 0309065623 Category : Science Languages : en Pages : 431
Book Description
The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific study of earthquakes is a surprisingly recent endeavor. Instrumental recordings of earthquakes were not made until the second half of the 19th century, and the primary mechanism for generating seismic waves was not identified until the beginning of the 20th century. From this recent start, a range of laboratory, field, and theoretical investigations have developed into a vigorous new discipline: the science of earthquakes. As a basic science, it provides a comprehensive understanding of earthquake behavior and related phenomena in the Earth and other terrestrial planets. As an applied science, it provides a knowledge base of great practical value for a global society whose infrastructure is built on the Earth's active crust. This book describes the growth and origins of earthquake science and identifies research and data collection efforts that will strengthen the scientific and social contributions of this exciting new discipline.
Author: F. A. Dahlen Publisher: Princeton University Press ISBN: 0691216150 Category : Science Languages : en Pages : 1040
Book Description
After every major earthquake, the Earth rings like a bell for several days. These free oscillations of the Earth and the related propagating body and surface waves are routinely detected at broad-band seismographic stations around the world. In this book, F. A. Dahlen and Jeroen Tromp present an advanced theoretical treatment of global seismology, describing the normal-mode, body-wave, and surface-wave methods employed in the determination of the Earth's three-dimensional internal structure and the source mechanisms of earthquakes. The authors provide a survey of both the history of global seismological research and the major theoretical and observational advances made in the past decade. The book is divided into three parts. In the first, "Foundations," Dahlen and Tromp give an extensive introduction to continuum mechanics and discuss the representation of seismic sources and the free oscillations of a completely general Earth model. The resulting theory should provide the basis for future scientific discussions of the elastic-gravitational deformation of the Earth. The second part, "The Spherical Earth," is devoted to the free oscillations of a spherically symmetric Earth. In the third part, "The Aspherical Earth," the authors discuss methods of dealing with the Earth's three-dimensional heterogeneity. The book is concerned primarily with the forward problem of global seismology--detailing how synthetic seismograms and spectra may be calculated and interpreted. As a long-needed unification of theories in global seismology, the book will be important to graduate students and to professional seismologists, geodynamicists, and geomagnetists, as well as to astronomers who study the free oscillations of the Sun and other stars.
Author: J. Koyama Publisher: Springer Science & Business Media ISBN: 9401732612 Category : Science Languages : en Pages : 207
Book Description
In seismology an earthquake source is described in terms of a fault with a particular rupture size. The faulting process of large earthquakes has been investigated in the last two decades through analyses of long-period seismo grams produced by advanced digital seismometry. By long-period far-field approximation, the earthquake source has been represented by physical parameters such as s~ismic moment, fault dimension and earthquake mag nitude. Meanwhile, destruction often results from strong ground motion due to large earthquakes at short distances. Since periods of strong ground motion are far shorter than those of seismic waves at teleseismic distances, the theory of long-period source process of earthquakes cannot be applied directly to strong ground motion at short distances. The excitation and propagation of high-frequency seismic waves are of special interest in recent earthquake seismology. In particular, the descrip tion and simulation of strong ground motion are very important not only for problems directly relevant to earthquake engineering, but also to the frac ture mechanics of earthquake faulting. Understanding of earthquake sources has been developed by investigating the complexity of faulting processes for the case of large earthquakes. Laboratory results on rock failures have also advanced the understanding of faulting mechanisms. Various attempts have been made to simulate, theoretically and empirically, the propagation of short-period seismic waves in the heterogeneous real earth.
Author: Agustín Udías Vallina
Author: Agustín Udías Vallina
Author: Shamita Das
Author: B. V. Kostrov
Author: Shamita Das
Author: D.E. James
Author: UDIAS
Author: Hussam Abdullah Busfar
Author: National Research Council
Author: F. A. Dahlen
Author: J. Koyama