This book deals with various theoretical and practical methods for real-time automatic signal processing in local (and regional) seismic networks and associated software developments, including extraction of small seismic signal from noisy observation by piecewise modeling and self-organizing state space modeling, determination of arrival time of S wave by locally multivariate stationary AT modeling, automatic interpretation of seismic signal by combining cumulativ sum and simulative annealing (CUSUM-SA), AR-filtering for local and teleseismic events, the currently high sensitivity seismic network running in Japan (Hi-net), PC-based computer package for automatic detection and location of earthquakes, real-time automatic seismic data-processing in seismic network running in eastern Sicily (Italy), the SIL (South Iceland Lowland) seismological data acquisition system and routine analysis in Iceland and Sweden.

In the last decade of the 20th century, there has been great progress in the physics of earthquake generation; that is, the introduction of laboratory-based fault constitutive laws as a basic equation governing earthquake rupture, quantitative description of tectonic loading driven by plate motion, and a microscopic approach to study fault zone processes. The fault constitutive law plays the role of an interface between microscopic processes in fault zones and macroscopic processes of a fault system, and the plate motion connects diverse crustal activities with mantle dynamics. An ambitious challenge for us is to develop realistic computer simulation models for the complete earthquake process on the basis of microphysics in fault zones and macro-dynamics in the crust-mantle system. Recent advances in high performance computer technology and numerical simulation methodology are bringing this vision within reach. The book consists of two parts and presents a cross-section of cutting-edge research in the field of computational earthquake physics. Part I includes works on microphysics of rupture and fault constitutive laws, and dynamic rupture, wave propagation and strong ground motion. Part II covers earthquake cycles, crustal deformation, plate dynamics, and seismicity change and its physical interpretation. Topics in Part II range from the 3-D simulations of earthquake generation cycles and interseismic crustal deformation associated with plate subduction to the development of new methods for analyzing geophysical and geodetical data and new simulation algorithms for large amplitude folding and mantle convection with viscoelastic/brittle lithosphere, as well as a theoretical study of accelerated seismic release on heterogeneous faults, simulation of long-range automaton models of earthquakes, and various approaches to earthquake predicition based on underlying physical and/or statistical models for seismicity change.

In the last decade of the 20th century, there has been great progress in the physics of earthquake generation; that is, the introduction of laboratory-based fault constitutive laws as a basic equation governing earthquake rupture, quantitative description of tectonic loading driven by plate motion, and a microscopic approach to study fault zone processes. The fault constitutive law plays the role of an interface between microscopic processes in fault zones and macroscopic processes of a fault system, and the plate motion connects diverse crustal activities with mantle dynamics. An ambitious challenge for us is to develop realistic computer simulation models for the complete earthquake process on the basis of microphysics in fault zones and macro-dynamics in the crust-mantle system. Recent advances in high performance computer technology and numerical simulation methodology are bringing this vision within reach. The book consists of two parts and presents a cross-section of cutting-edge research in the field of computational earthquake physics. Part I includes works on microphysics of rupture and fault constitutive laws, and dynamic rupture, wave propagation and strong ground motion. Part II covers earthquake cycles, crustal deformation, plate dynamics, and seismicity change and its physical interpretation. Topics covered in Part I range from the microscopic simulation and laboratory studies of rock fracture and the underlying mechanism for nucleation and catastrophic failure to the development of theoretical models of frictional behaviors of faults; as well as the simulation studies of dynamic rupture processes and seismic wave propagation in a 3-D heterogeneous medium, to the case studies of strong ground motions from the 1999 Chi-Chi earthquake and seismic hazard estimation for Cascadian subduction zone earthquakes.

In 1999, two earthquakes occurred in the Istanbul-Marmara region of Turkey and the Athens-Corinth region of Greece, and an increased risk of further events caused great concern among the earth science community. This book presents and discusses the latest results from studies of the Izmit-D zce and Athens earthquakes and assesses the data that are available and relevant to the geology, seismology, tectonics, geodesy and other fields related to earthquake studies and to evaluate earthquake hazard potential.

Vlastislav Cerveny Ivan Psencik Academy of Sciences of the Czech Charles University Republic Faculty of Mathematics & Physics Geophysical Institute Dep. of Geophysics Bocni II, 1401 Ke Karlovu 3 14131 Praha 4 12116 Praha 2 Czech Republic Czech Republic e-mail: ip@ig. cas. cz e-mail: vcerveny@seis. karlov. mff. cuni. cz (c) Birkhauser Verlag, Basel, 2002 Pure appl. geophys. 159 (2002) 1403-1417 I Pure and Applied Geophysics 0033-4553/02/081403-15 $ 1. 50 + 0. 20/0 Coupled Anisotropic Shear-wave Ray Tracing in Situations where Associated Slowness Sheets Are Almost Tangent l P. M. BAKKER Summary- For shear waves in anisotropic media a frequency-dependent transport equation is derived, which involves coupling of both shear modes if the slowness vector points in adirection for which the associated slowness surfaces are (almost) tangent. This is achieved by averaging the Hamiltonians for both uncoupled shear modes. No assumption on weak anisotropy is made, and the shear polarisation is perpendicular to the P-wave polarisation for the actual slowness direction instead of an isotropically approximated P-wave polarisation. These are the main differences compared with the so-called zero-order quasi-isotropic approach. Key words: Anisotropy, ray tracing, shear wave. J. Introduction Reliable modelling of polarisations for shear waves in anisotropic media is relevant in the context of imaging mode-converted (OBCjOBS) data in cases where not only poSY, but also poSH conversions take place. In such situations it may be necessary to use the polarisation direction for consistent continuation of the different wave modes and for appropriate imaging.

In September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data center, and onsite inspections, to verify compliance. The problem of identifying small-magnitude banned nuclear tests and discriminating between such tests and the background of earthquakes and mining-related seismic events, is a challenging research problem. Because they emphasize CTBT verification research, the 12 papers in this special volume primarily addresses regional data recorded by a variety of arrays, broadband stations, and temporarily deployed stations. Nuclear explosions, earthquakes, mining-related explosions, mine collapses, single-charge and ripple-fired chemical explosions from Europe, Asia, North Africa, and North America are all studied. While the primary emphasis is on short-period, body-wave discriminants and associated source and path corrections, research that focuses on long-period data recorded at regional and teleseismic distances is also presented Hence, these papers demonstrate how event identification research in support of CTBT monitoring has expanded in recent years to include a wide variety of event types, data types, geographic regions and statistical techniques.

In many past and recent earthquakes it has been shown that the local conditions and, in particular, the local geology have a great influence on the observed seismic ground motion and, consequently, on the damage distribution in housing, industrial stock, and life-lines. Seismic microzoning is the usual procedure to have these local effects taken into account for engineering design and land-use planning, being a useful tool for earthquake risk mitigation. This volume presents a collection of papers mainly originated from a workshop on Seismic Microzoning, organized during the 23rd General Assembly of the European Geophysical Society (EGS) in Nice, France in April 1998. The workshop dealt with various geophysical tools for analysing the effects of the local soils of subsurface geology on seismic ground motion, namely the methods using experimental data such as microtremors, and the theoretical/numerical 1-D and 2-D modelling methods. Additional contributions discussing techniques for characterising soil properties, microzoning applications to several urban areas, and others were added to the volume to broaden this important topic.

This volume presents summaries of recent research results on the related subjects of source processes and explosion yield estimation, which are important elements of any treaty verification system. The term Source Processes, in the context of nuclear test monitoring, refers to a wide range of research topics. In a narrow definition, it describes the complex physical phenomena that are directly associated with a nuclear explosion, and the catastrophic deformation and transformation of the material surrounding the explosion. In a broader sense, it includes a host of topics related to the inference of explosion phenomena from seismic and other signals. A further widening of the definition includes the study and characterization of source processes of events other than nuclear, such as earthquakes and, in particular, mining explosions. This latter research is especially important relative to the question of identifying and discriminating nuclear explosions from other seismic events. Explosion Yield Estimation deals with the corresponding inverse problem of inferring explosion source characteristics through analyses of the various types of seismic signals produced by the explosion. This is a complex technical task which has been the focus of some of the most contentious treaty monitoring debates. The current compilation of eight articles on Source Processes and six articles on Explosion Yield Estimation gives a good representation of state-of-the-art research currently being conducted in the broad area of seismic source characterization in the context of nuclear test monitoring.

Vol. t59. 2002 J damaged zone on the rock mass. Collins el al. examine the benefits of employing small-scale microseismic and acoustic emission systems to investigate the temporal fracture mechanics of microcrack formation associated with a tunnel sealing experiment at the Underground Research Laboratory nuclear waste test site in Canada. They associate microseismic events with clusters of acoustic emissions and outline that both types of sources are generally characterized by deviatoric failure components. Using the same experimental setup, Hazzard el al. employed a bonded- particle model to simulate shear microfraclures induced by the lunnel excavation. Comparing Ihe modeling results with information provided by the moniloring of microseismicity and acoustic emissions, the authors identify similarities in both the presence of foreshocks associated with macro-slip events, and the pallerns of energy release during loading. Hildyard and Young allempt to model the seismic wave interaction with fractured rock surrounding underground openings, through exper- iments such as a rockbursl simulation, in situ events generating acoustic emissions, and laboratory fractures. Their results highlight that realistic wave modeling around openings requires the presence of a stress-dependent fracture stiffness coupling the surfaces of the fracture. Ultrasonic attenuation tomography and enhanced velocity tomography were studied by D~bski and Young for an earlier laboratory experiment of thennally induced fractures in granite.

On September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data center (IDC), and on-site inspections to verify compliance. Seismic methods play the lead role in monitoring the CTBT. This volume concentrates on the measurement and use of surface waves in monitoring the CTBT. Surface waves have three principal applications in CTBT monitoring: to help discriminate nuclear explosions from other sources of seismic energy, to provide mathematical characterizations of the seismic energy that emanates from seismic sources, and to be used as data in inversion for the seismic velocity structure of the crust and uppermost mantle for locating small seismic events regionally. The papers in this volume fall into two general categories: the development and/or application of methods to summarize information in surface waves, and the use of these summaries to advance the art of surface-wave identification, measurement, and source characterization. These papers cut across essentially all of the major applications of surface waves to monitoring the CTBT. This volume therefore provides a general introduction to the state of research in this area and should be useful as a guide for further exploration.

On September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data center (IDC), and on-site inspections to verify compliance. Successful monitoring of a CTBT requires that we detect and identify all nuclear explosions. Since many events of concern will be too small to be detected teleseismically, this capability requires the use of regional-distance seismograms. The complexity of regional seismograms presents many technical challenges for a monitoring program. This issue focuses on problems associated with regional wave propagation through complex media. It includes papers that investigate regional variations of elastic and anelastic properties of Eurasia, the blockage of regional phases by sedimentary basins, methods for modeling regional wave propagation and for calibrating seismic wave paths in order to extract amplitude variations and source parameters. These papers illustrate the research and development necessary for acquiring an understanding of regional wave propagation which in turn provides the foundation for operational tools used to monitor a CTBT.

In September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data centre (IDC), and on-site inspections, to verify compliance. This volume contains research papers focusing on seismic ecent location in the CTBT context. The on-site inspection protocol of the treaty specifies a search area not to exceed 1000 square km. Much of the current research effort is therefore directed towards refining the accuracy of event location by including allowances for three-dimensional structure within the Earth. The aim is that the true location of each event will lie within the specified source zone regarding postulated location. The papers in this volume cover many aspects of seismic event location, including the development of algorithms suitable for use with three-dimensional models, allowances for regional structure, use of calibration events and source-specific station corrections. They provide a broad overview of the current international effort to improve seismic event location accuracy, and the editors hope that it will stimulate increased interest and further advances in this important field.

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.

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.

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.

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.

Serendipity placed David Johnston on Mount St. Helens when the volcano rumbled to life in March 1980. Throughout that ominous spring, Johnston was part of a team that conducted scientific research that underpinned warnings about the mountain. Those warnings saved thousands of lives when the most devastating volcanic eruption in U.S. history blew apart Mount St. Helens, but killed Johnston on the ridge that now bears his name. Melanie Holmes tells the story of Johnston's journey from a nature-loving Boy Scout to a committed geologist. Blending science with personal detail, Holmes follows Johnston through encounters with Aleutian volcanoes, his work helping the Portuguese government assess the geothermal power of the Azores, and his dream job as a volcanologist with the U.S. Geological Survey. Interviews and personal writings reveal what a friend called "the most unjaded person I ever met," an imperfect but kind, intelligent young scientist passionately in love with his life and work and determined to make a difference.

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.

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.