This collection of conference papers describes state-of-the-art methodologies and algorithms used in the treatment of inverse problems, focusing on seismology and image processing. The papers also describe new general methodologies for analysis and solution of inverse problems by means of statistical and deterministic algorithms. The book gives a glimpse of recent techniques, many of which are still under development.

requiring the adaptation of probabilistic maps to design ground motions; and (d) the generalization of design parameters to locations where there is little seismic history. Maximum displacements, velocities, and, based on the European Build ing Code EC8, design ground acceleration maps have thus been produced by ZivCic et al. for Slovenia, Marku ic et al. for Croatia, Bus et al. for Hungary, and Radulian et al. for Romania. The last two contributions in the volume are dedicated to studies of local site effects that could affect the microzonation of large urban areas. Moldoveanu et al. employed a technique based on the modal summation and finite dif ferences to calculate the expected ground motion in the capital city of Bucha rest due to large intermediate-depth Vrancea earthquakes. Their results outline that the presence of alluvial sediments and the possible variation of event scenario require the use of all three components of motion for a reliable determination of the seismic input. The study of Marmureanu et al., more limited in scope, offers a laboratory analysis of the attenuation effects for sur face layers. The authors confirm that seismic attenuation in sedimentary layers is a function of the strain levels induced by large earthquakes, and find that the quality factor is nearly constant over a relatively wide frequency range, between 7 and 100 Hz."

DEKORP, the German continental reflection seismic program, was the major focus of deep seismic research in Germany in the 1980s and 1990s. The seismic sections provided fundamental new insight into deep geological structure of the European continent and the dynamics of continental formation. They formed the basis for worldwide comparative studies of orogenic structure. The complicated signature of the reflections from the deep crust indicated that new processing and interpretation techniques must be considered to better image the crystalline crust. Results of these efforts, including pre-stack migration, 3-D imaging, shear waves and seismic anisotropy, are presented in this special volume. In part, the articles open the perspective to new and future research. In part, they document research activity triggered by technical and interpretational questions raised by DEKORP field work and profiling results. Many of the presented methods can find immediate application in industrial seismic prospecting.

204 Pure app!. geophys. , P. Reasenberg demonstrated that in Cascadia earthquakes are four times more likely to be foreshocks than in California. Many speakers emphasized the regional differences in all earthquake parameters, and it was generally understood that basic models of the earthquake occurrence must be modified for regional application. The idea that the focal mechanisms of foreshocks may differ from that of background activity was advocated by Y. Chen and identified by M. Ohtake as possibly the thus far most neglected property of foreshocks, in efforts to identify them. S. Matsumura proposed that focal mechanism patterns of small earthquakes may differ character istically near locked fault segments into which fault creep is advancing. Considerable discussion was devoted to the status of the seismic gap hypothesis because M. Wyss argued that the occurrence of the M 7. 9, 1986, Andreanof Islands earthquake was a confirmation of Reid's rebound theory of earthquakes and thus of the time predictable version of the gap hypothesis, whereas Y. Kagan believed he could negate this view by presenting a list of nine earthquake pairs with M> 7. 4, moment centroid separation of less than 100 km, and time difference less than about 60% of the time he estimated it would take plate motions to restore the slip of the first event.

Modern seismology is a relatively new science; most current ideas originated no earlier than the latter half of the nineteenth century. The focus of this book is on seismological concepts, how they originated and how they form our modern understanding of the science. A history of seismology falls naturally into four periods: a largely mythological period previous to the 1755 Lisbon earthquake; a period of direct observation from then to the development of seismometers in the late 19th century; a period during which study of seismic arrival times were used to outline the structure of the earth's interior extending the 1960s; the modern era in which all aspects of seismic waves are used in combination with trial models and computers to elucidate details of the earthquake process. This history attempts to show how modern ideas grew from simple beginnings. Ideas are rarely new, and their first presentations are often neglected until someone is able to present the evidence for their correctness convincingly. Much care has been used to give the earliest sources of ideas and to reference the basic papers on all aspects of earthquake seismology to help investigators find such references in tracing the roots of their own work.

Earthquakes in shallow subduction zones account for the greatest part of seismic energy release in the Earth and often cause significant damage; in some cases they are accompanied by devastating tsunamis. Understanding the physics of seismogenic and tsunamigenic processes in such zones continues to be a challenging focus of ongoing research. The seismologic and geodetic work reported in this volume highlights the recent advances made toward quantifying and understandig the role of shallow plate coupling in the earthquake generation process. The relation between regional seismotectonics, features in the downgoing plate, and the slip distribution in earthquakes are examined for recent and great historical events. In addition to papers reporting new results, review articles on tsunami and tsunamigenic earthquakes and depth dependent plate interface properties are presented. These observational results, along with complementary laboratory and theoretical studies, can assist in assessing the seismic potential of a given region.

Volcanoes are some of the most dramatic expressions of the powerful tectonic forces at work in the Earth beneath our feet. But volcanism, a profoundly important feature of Earth, and indeed of other planets and moons too, encompasses much more than just volcanoes themselves. On a planetary scale, volcanism is an indispensable heat release mechanism, which on Earth allows the conditions for life. IIt releases gases into the atmosphere and produces enormous volumes of rock, and spectacular landscapes - landscapes which, during major eruptions, can be completely reshaped in a matter of hours. Through geological time volcanism has shaped both climate and biological evolution, and volcanoes can affect human life, too, for both good and ill. Yet, even after much study, some of the fundamental aspects of volcanicity remain mysterious. This Very Short Introduction takes the readers into the inferno of a racing pyroclastic current, and the heart of a moving lava flow, as understood through the latest scientific research. Exploring how volcanologists forensically decipher how volcanoes work, Michael Branney and Jan Zalasiewicz explain what we do (and don't) understood about the fundamental mechanisms of volcanism, and consider how volcanoes interact with other physical processes on the Earth, with life, and with human society. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.

Variations in seismic Q are sensitive to a much greater extent than are seismic velocity variations on factors such as temperature, fluid content, and the movement of solid state defects in the earth. For that reason an understanding of Q and its variation with position in the earth and with time should provide information in earth's tectonic evolution, as well as on aspects of its internal structure. Progress in understanding Q has suffered from difficulty in obtaining reliable amplitude data at global and temporary stations. Moreover, laboratory determinations of Q, until recently, were most often made at frequencies much higher than those measured by seismologists for waves propagating through the earth. Recent advances in seismic station distribution and quality, as well as in methodology at both high and low fequencies, have greatly improved the quality of observational data available to seismologists from global stations. Concurrent advances have been made in measuring Q using laboratory samples at frequencies that pertain to the earth and in theoretical understanding of seismic wave attenuation. Papers of this volume present new information on Q in the earth from several perspectives: methodology, results from global and regional observations of both body and surface waves, laboratory measurements, and theoretical understanding. The editors believe that we have reached a new threshold in Q studies and that advances in data quality and methodology will spur increased interest in this difficult, but interesting field.

The perturbation of the earth by mankind causes earthquakes in a variety of situations. This phenomenon continues to be a major concern to engineers and scientists concerned with the mitigation of the consequences of this seismicity, as well as better understanding the processes at its origin. The present volume contains twelve papers from six countries, dealing with observations of triggered and induced seismicity in four continents. The reported cases include seismicity due to hard-rock mines, coal mines, underground research facilities for nuclear waste disposal, water injections, reservoirs, acquifers and oil fields. This volume provides case studies of previously unavailable observations of this phenomenon, investigations of the cause and source mechanism of seismic events, studies of source location distributions, determinations of seismic source parameters, cases of the use of such parameters in assessing rockburst hazard in mines, and measurements of velocity an attenuation properties of rock masses. The present collection of papers provides an excellent indication of the current state of the art and new developments in this area of research.

This book treats various generalizations of the classical O'Doherty-Anstey formula in order to describe stratigraphic filtering effects. These are the effects that can be observed when elastic and electromagnetic waves propagate through multilayered structures. Our aim was to treat this topic in a comprehensive manner and present compact results in a didactically simple way, emphasizing the physics of the wave-propagation phenomena. We do not claim mathematical rigidity in all our derivations, however, we are pleased to have obtained quite simple descriptions of scattering, transmission and reflection of wavefields in acoustic, elastic, and poroelastic media which can be useful for various seismological and non-seismological applications.

This book deals with the application of fractal and nonlinear time-series analysis to seismicity and earthquakes within the framework of earthquake prediction research. Emphasis is on theoretical foundations as well as practical implementation and pitfalls to enable readers to conduct their own analyses. The theoretical parts include introductions to fractals and multifractals, the relation between fractal dimension and entropy, the Hurst phenomenon, basic ideas of low-dimensional chaotic dynamics and a roadmap of nonlinear time-series analysis. Practical implementation is discussed in each case and synthetic data sets are analyzed. Fractal methods are applied to landslide and seismicity patterns in space and time, nonlinear analysis is carried out for radon and strain data as well as earthquake intervals. Due to the comprehensive coverage of theoretical background and step-by-step applications, readers of all levels will benefit from this book.

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.

This volume contains 18 papers from 8 countries dealing with different aspects of triggered and induced seismicity. In situ observations of the phenomenon include examples of seismicity due to reservoirs, hard-rock mines, coal mines, mine collapses, brine production caverns, fluid injections, and geothermal hot-dry-rock projects. High-frequency acoustic emission studies from laboratory experiments and hard-rock mines have also been reported. Besides providing case studies of previously unavailable observations of seismicity, the present volume contains investigations of the causes and source mechanism of seismic events, determination of source parameters, seismic hazard as related to the design of support systems for underground openings and procedures for closure of brine production caverns, and the use of seismic and non-destructive techniques in assessing rock damage, measuring dynamic elastic moduli and detecting discontinuities. This collection of papers provides an excellent indication of the state of the art, recent developments and outstanding challenges facing scientists and engineers in understanding the causes and alleviating the effects of induced seismicity.

The special issue contains contributions presented at the international workshop Seismic waves in laterally inhomogeneous media IV, which was held at the Castle of Trest, Czech Republic, May 22-27, 1995. The workshop, which was attended by about 100 seismologists from more than 10 countries, was devoted mainly to the current state of theoretical and computational means of study of seismic wave propagation in complex structures. The special issue can be of interest for theoretical, global and explorational seismologists. The first part contains papers dealing with the study and the use of various methods of solving forward and inverse problems in complicated structures. Among other methods, discrete-wave number method, the finite-difference method, the edge-wave supperposition method and the ray method are studied and used. Most papers contained in the second part are related to the ray method. The most important topics are two-point ray tracing, grid calculations of travel times and amplitudes and seismic wave propagation in anisotropic media.

The special issue contains contributions presented at the international workshop Seismic waves in laterally inhomo- geneous media IV, which was held at the Castle of Trest, Czech Republic, May 22-27, 1995. The workshop, which was attended by about 100 seismologists from more than 10 countries, was devoted mainly to the current state of theoretical and computational means of study of seismic wave propagation in complex structures. The special issue can be of interest for theoretical, global and explorational seismologists. The first part contains papers dealing with the study and the use of various methods of solving forward and inverse problems in complicated structures. Among other methods, discrete-wave number method, the finite-difference method, the edge-wave supperposition method and the ray method are studied and used. Most papers contained in the second part are related to the ray method. The most important topics are two-point ray tracing, grid calculations of travel times and amplitudes and seismic wave propagation in anisotropic media.

Induced seismic events are of high scientific and economic significance. They are the result of human activities interacting with regional and local tectonics, changing the local crustal stress state by mining, extraction of rock masses, injection of fluids into the rock massif, and by changing the surface loading and pore pressure state near large reservoirs. Within Europe the study of induced seismic events has a long tradition and international scientific organizations have actively stimulated the co-operation in this field. During its General Assembly in September 1994, the European Seismological Society organized the symposium "Induced Seismic Events." The focus of this symposium was concentrated on induced events in central and eastern Europe, as well as in the former Soviet Union. The major contributions to the symposium, and also some Chinese, Canadian, and South African results are presented here. Case studies as well as data analyses and methodological studies are included. Seismologists and specialists working in the field of geohazard prevention will find much information in this volume that is pertinent to their work.

Digital signal processing has become an integral part of observational seismology. Seismic waveforms and the parameters commonly extracted from them are strongly influenced by the effects of numerous filters, both within the earth and within the recording system. With the advent of numerous software tools for the processing of digital seismograms, seismologists have unprecedented power in extracting information from seismic records. These tools are often based on sophisticated theoretical aspects of digital signal processing which, to be used properly, need to be understood. This book is aimed at observational seismologists and students in geophysics trying to obtain a basic understanding of those aspects of digital signal processing that are relevant to the interpretation of seismograms. It covers the basic theory of linear systems, the design and analysis of simple digital filters, the effect of sampling and A/D conversion, the calculation of `true ground motion', and the effects of seismic recording systems on parameters extracted from digital seismograms. It contains numerous examples and exercises together with their solutions.

How to better protection of our architectural heritage in the event of earthquakes? The vulnerability of cultural artifacts necessitates the working out of a system which takes into account the problems of architecture, engineering and seismology among others. Written by architects and engineers, this book attempts to offer answers and give guidelines for both architects and engineers working in this field.

This volume presents a unique compendium of papers assessing the effects of volcanism on lakes, as recorded by the volcaniclastic sediments deposited within them. The unifying theme is that the effects of volcanism on lacustrine sedimentation are diverse and distinctive, and that volcaniclastic lacustrine sediments hold the key to understanding a range of processes and events that cannot be readily addressed by the study of any non-volcanic lakes.

Thirteen papers, with authors from nine countries, examine both modern and ancient eruption-affected lacustrine deposits. Volcanic eruptions affect lakes and their deposits in many ways, and these papers evaluate processes and products of volcanic eruptions within lakes, of tectonically impounded lakes strongly influenced by volcanism, of eruption-impounded lakes and of general factors controlling sedimentation of vitric ash and pumice. Tephrastratigraphic studies also take advantage of the exceptional preservation of thin laminae in quiet lakes to precisely date episodes in the evolution of long-lived lakes and their catchment areas, and to understand how volcanism affects normal lacustrine processes.

The volume as a whole is an unparalleled source of information on all aspects of the physical sedimentary results of volcanism in lacustrine settings, and serves as a complement to other studies concerned primarily with thermal and geochemical characteristics of lakes within volcanic craters.

If you are a member of the International Association of Sedimentologists, for purchasing details, please see: http: //www.iasnet.org/publications/details.asp?code=SP30

This book gives a comprehensive, theoretical account of the wave-wave interaction process responsible for high acoustic noise levels, including: a geometric description of the interaction mechanism, which provides the basis for a full-wave analysis of the source process, the inclusion of both the monogeneous and inhomogeneous components of the wave-induced pressure field in the analytical description of the source, an examination of the relative contributions of the sum and difference-frequency components of the wave interaction process, the removal of the deep-water assumption of earlier analyses, and the development of an "exact" analytical expression which allows the source function of the wave-induced pressure field to be calculated over the whole frequency-wave number domain.

A workshop on Induced Seismicity was organized during the 27th General Assembly of the International Association of Seismology and Physics of Earth's Interior (IASPEI) in Wellington, New Zealand during January 10-21, 1994. This volume presents a collection of 16 papers accepted for publication which accrued from this workshop. The first three papers address mining activity related to induced seismicity. The fourth paper deals with water injection induced seismic activity, while the remaining 12 papers treat several aspects of water reservoir induced earthquakes. Globally, the Koyna dam creating Shivajisagar Lake in Maharashtra, India, continues to be the most significant site of reservoir-induced earthquakes. With the increase in the number of cases of induced seismicity, there is a growing concern among planners, engineers, geophysicists and geologists to understand the environment conducive to this phenomenon. While the changes in pore-fluid pressure have been identified as the key factor in inducing earthquakes, the phenomenon itself is still poorly understood. This reality thus makes the study of the induced seismicity very important and this volume timely.

The 1993 Southwest Hokkaido Earthquake of Magnitude 7. 9 (July 12, 22: 17 JST) caused serious tsunami disasters in the southwestern part of Hokkaido, particularly on Okushiri Island (a tiny island off the southwest coast of Hokkaido with a population of about 4,500 at the time of earthquake). Of 230 casualties, including 28 missing, about 200 deaths are attributable to the tsunami. We have conducted detailed field surveys of tsunami disasters to learn lessons from this costly natural experiment for the future prevention of similar tsunami disasters. Our field work was conducted in four surveys totaling 39 days. During the first field survey (July 16 through July 21, 1994), we worked mostly on the estimation of the subsidence of Okushiri Island during the earthquake. Hence, our main work on tsunami disasters initiated from the second field survey (July 31 through Aug. 15, 1994). Several groups have conducted detailed surveys of the distribution of tsunami runup height as measured from the level of sea water (TsUJI et al. , 1 994a, b; MATSUTOMI and SHUTO, 1994; GOTO et al. , 1994). Such a precise runup height distribution is essential for characterizing tsunami, including its overall size. Indeed, the height distribution is the fundamental data for inferring earthquake source parameters through the simulation of tsunami generation (TAKAHASHI et al. , 1994; IMAMURA et al. , 1994; TSUJI et al. , 1994a; SATAKE and TANIOKA 1994; ABE, 1994; TANIOKA et al. , in review).

Seismic imaging methods are currently used to produce images of the Earth's subsurface properties at diverse length scales, from high-resolution, near-surface environmental studies for oil and gas exploration to long-period images of the entire planet. This book presents the physical and mathematical basis of imaging algorithms in the context of controlled-source reflection seismology. The approach taken is motivated by physical optics and theoretical seismology. The theory is constantly put into practice via a graded sequence of computer exercises using the widely available SU (Seismic Unix) software package.

Digital signal processing has become more and more an integral part of observational seismology. While it offers unprecedented power in extracting information from seismic signals, it comes at the price of having to learn a variety of new skills. Dealing with digital seismic data requires at least a basic understanding of digital signal processing. Taking the calculation of true ground motion as the guiding problem, this course covers the basic theory of linear systems, the design and analysis of simple digital filters, the effect of sampling and A/D conversion and an introduction to spectral analysis of digital signals. It contains a number of examples and exercises that can be reproduced using the PITSA software package (Scherbaum and Johnson 1993) or similar programs.

Tectonic processes occurring in shallow subduction zones around the world generate the majority of large, damaging earthquakes. Last decade brought more understanding of these processes, showing however, their complexity and diversity from place to place. A full understanding of the seismotectonics of shallow subduction zones is yet to be achieved, however the ambitious goal of forecasting at least the largest of earthquakes is certainly worth pursuing. The present volume reports the most recent research in this field and includes theoretical as well as observational works concerning seismicity, mechanics and seismic potential of subduction segments around the world. Topics covered in Part II include new inversions for two great Alaska-Aleutians earthquakes (1957 Aleutian and 1964 Prince William Sound), seismicity trends and potential for large earthquakes in the Alaska-Aleutian region, rupture process of large earthquakes in Northern Mexico, global variability in subduction thrust zone-forearc systems, and possible causal relationship between large subduction earthquakes and volcanic eruptions. Part II is a companion volume to Part I, published in 1993.