Vol. 157, 2000 spanning across disciplines and national boundaries gives cause for optimism. New participation in ACES to extend its existing synergies is welcomed. We wish to thank the scientific participants of The APEC Cooperation for Earthquake Simulation (ACES) and the contributors to this book. We express appreciation to the Australian, Chinese, Japanese and USA governments for supporting the establishment of ACES. We gratefully acknowledge funding support by the Australian government's Department of Industry, Science and Resources, The University of Queensland, Japan's Science and Technology Agency through its Research Organisation for Information Science and Technology, the Chinese Ministry of Science and Technology, and the National Science Foundation of China. We acknowledge with appreciation additional workshop sponsorship pro vided by SGI (Silicon Graphics). Special thanks to QUAKES team members (Tracy Paroz, David Place, Steffen Abe, Dion Weatherley and Steven Jaume) and Kim Olsen who provided assistance to the Editors. Peter Mora would also like to thank Evelyne Meier. REFERENCES I-st ACES Workshop Proceedings (1999), ed. Mora, P. (ACES, Brisbane, Australia, ISBN 1 86499 121 6), 554 pp. APEC Cooperation for Earthquake Simulation: http: //quakes. earth. uq. edu. au/ACES ACES Inaugural Workshop: http: //quakes. earth. uq. edu. au/ACES_ WS Raul Madariaga Peter Mora QUAKES Laboratoire de Geologie Department of Earth Sciences Ecole Normale Superieur The University of Queensland 24 Rue Lhomond 4072 Brisbane, Qld F-75231 Paris, Cedex 05 Australia France mora@earth. up. edu. au madariag@geologie. ens."

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.

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.

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."

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.

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.

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.

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.

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.

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 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.

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.

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).

AVO (SEG Investigations in Geophysics No. 16) by Satinder Chopra and John Castagna begins with a brief discussion on the basics of seismic-wave propagation as it relates to AVO, followed by a discussion of the rock-physics foundation for AVO analysis including the use of Gassmann's equations and fluid substitution. Then, the early seismic observations and how they led to the birth of AVO analysis are presented. The various approximations for the Zoeppritz equations are examined, and the assumptions and limitations of each approximation are clearly identified. A section on the factors that affect seismic amplitudes and a discussion of the processing considerations important for AVO analysis are included. A subsequent section explores the various techniques used in AVO interpretation. Finally, topics including the influence of anisotropy in AVO analysis, the use of AVO inversion, estimation of uncertainty in AVO analysis, converted-wave AVO, and the future of the AVO method are discussed. Equally helpful to new entrants into the field as well as to seasoned workers, AVO will provide readers with the most up-to-date knowledge on amplitude variation with offset.

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.

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.

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.

ing within the downgoing plate, and appears to be assoeiated with segmentation of the subdueting plate produeed by forees related to the subduetion of the Louisville Ridge. To analyze fault plane heterogeneities in the northern Solomon Islands subdue- tion segment and their association with rupture eharaeteristics in general and the existenee of earthquake doublets in partieular, Xv and SCHWARTZ study in detail two sets of doublets, from 1974 and 1975, and then reloeate 85 underthrusting events in the area. The authors find that few smaller magnitude events overlap asperity regions, and that the majority of small magnitude underthrusting earth- quak es oeeupy a segment that has never experieneed a magnitude greater than 7.0 earthquake in the historie times. It will be of great value to soeiety when seismologists and geophysieists are able to monitor and prediet the pattern of geophysieal phenomena assoeiated with subduetion; this issue presents a modest step towards this goal. PAGEOPH, Vol. 140, No. 2 (1993) 0033 ~4553;93;020 183 ~ 28$1.50 + 0.20;0 (c) 1993 Birkhauser Verlag, Basel Slip Partitioning along Major Convergent Plate Boundaries 2 GUANG YU,l STEVEN G. WESNOUSKY,l and GORAN EKSTROM Abstract-Along plate boundaries characterized by oblique convergence, earthquake slip vectors are commonly rotated toward the normal of the trench with respect to predicted plate motion vectors. Consequently, relative plate motion along such convergent margins must be partitioned between displacements along the thrust plate interface and deformation within the foreare and back-are regions.

In the early 1950s microseisms, with characteristic amplitudes of several micro meters, were considered insignificant relative to powerful destructive earthquakes. They were understood to be noise, as natural fluctuations, not carrying any in formation and distorting recordings on seismograms. Intensive investigations over subsequent decades have shown, however, that microseisins are only a single facet of a huge complex of phenomena comprising cyclone movement over oceans, sea roughness, infrasound, geomagnetic micropulsations, terrestial of these phenomena proved to be confined in time currents, etc. The source and space, whereas their effects propagated over global distances. This could be interpreted as a case of natural "remote sensing." It should be mentioned that all of the evidence gathered in the last few decades supports the theory of M. S. Longuet-Higgins published in 1950. The author has been engaged in problems of microseisms since 1955 and is deeply convinced that these phenomena are not only of theoretical interest but may also find practical application in meteorology, oceanology, navigation and other areas. She hopes. that this book will stimulate further research as well as new approaches to practical problems."