Earthquakes are the expression of the continuing evolution of the Earth planet and of the deformation of its crust and occur worldwide; while the largest events (M>7. 5) concentrate on plate boundary areas and active plate interiors, moderate earthquakes may take place, if rarely, in all continental areas and may turn catastrophic in areas with poor building construction practice, as tragically shown by the sequence of earthquakes striking the Caucasus region in recent years (Spitak, Armenia, 1988; Rutbar, W. Iran, 1990; Ratcha, Georgia, 1991; Erzincan, E. Turkey, 1992). Vulnerability to disaster is increasing as urbanisation and development occupy more areas that are prone to the effects of significant earthquakes. In order to minimize the loss of life, property damage and social and economic disruption caused by earthquakes, it is essential that reliable estimates of seismic hazard be available to national decision makers and engineers for land use planning and improved building design and construction. While short- and mid-term earthquake prediction may one day be able to reduce significantly the death toll of earthquakes, the environmental effects (collapse of buildings and infrastructures, disruption of the productive chain, human resettlement) can be reduced only through a long-term prevention policy in earthquake-prone areas based on the assessment of seismic hazard and risk, the implementation of safe building construction codes, the increased public awareness on natural disasters, a strategy of land-use planning taking into account the seismic hazard and the occurrence of other natural disasters.

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."

Routine seismic monitoring in mines was introduced over 30 years ago with two main objectives in mind: * immediate location of larger seIsmIC events to guide rescue operations; * prediction of large rockmass instabilities. The first objective was achieved fairly quickly, but with the subsequent development of mine communication systems, its strategic importance has diminished. The very limited success with prediction can, at least partially, be attributed to three factors: * seismic monitoring systems based on analogue technology that provided noisy and, frequently, poorly calibrated data of limited dynamic range; * the non-quantitative description of a seismic event by at best its local magnitude; and * the resultant non-quantitative analysis of seismicity, frequently through parameters of some statistical distributions, with a somewhat loose but imaginative physical interpretation. The introduction of modern digital seismic systems to mines and progress in the theory and methods of quantitative seismology have enabled the implementation of realtime seismic monitoring as a management tool, quantifying rockmass response to mining and achieving the first tangible results with prediction. A seismic event, being a sudden inelastic deformation within the rockmass, can now routinely be quantified in terms of seismic moment, its tensor, and radiated seismic energy, so that the overall size of, and stress released at, the seismic source can be estimated.

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.

This manual describes all aspects of a field seismic crew, on land, in terms of their relevance to the activities of the birddog, who is the company's representative on that field crew. In particular, it descibes the essential functions of the birddog which are data quality control (all forms) and testing to ensure optimum data quality. Some fundamental concepts of the seismic methods are described. Written in a way that is not specific to any particular equipment or technology, it concentrates on the principles and methods of supervision which are common to all procedures and equipment.

This volume presents different studies carried out on induced seismicity, both from experimental and theoretical viewpoints. Several examples of seismic activity induced by underground nuclear explosions, impoundment of artificial reservoirs, and mining activities are given and discussed. Another important subject which is covered is earthquakes induced by other large earthquakes. Further, tectonic stress release in the immediate vicinity of an underground nuclear explosion is treated. The release produces aftershocks of small magnitude, usually for several weeks, occurring a few kilometers within the shot point. This phenomenon is of importance in the context of monitoring a Comprehensive Test Ban Treaty.

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.

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.

Earthquake Hazard and Risk is a book summarizing selected papers presented at the 27th General Assembly of the International Association of Seismology and Physics of the Earth's Interior (Wellington, January 1994). The papers, rigorously scrutinized by an international board of referees, cover some recent aspects of current research in earthquake hazard and seismic risk. They address the algorithms and methodology used in seismological applications, the reliability of these techniques with the decreasing level of probability and uncertainty associated with various seismotectonic settings, the physical and statistical nature of earthquake occurrences, strong ground motions and effects of surface seismogeological conditions. A special effort has been made to include papers that illustrate the assessment of earthquake hazard and seismic risk through applications at sites in either inter-plate or intra-plate tectonic settings. Of particular interest is hazard assessment in regions of rare large earthquakes. The book is suitable for those interested in earthquake hazard and seismic risk research as well as a more general audience of seismologists, geophysicists and Earth scientists. It is also useful for authorities responsible for public safety and natural hazard mitigation plans and for insurance companies.

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).

Recent advances in the power of inversion methods, the accuracy of acoustic field prediction codes, and the speed of digital computers have made the full field inversion of ocean and seismic parameters on a large scale a practical possibility. These methods exploit amplitude and phase information detected on hydrophone/geophone arrays, thereby extending traditional inversion schemes based on time of flight measurements. Full field inversion methods provide environmental information by minimising the mismatch between measured and predicted acoustic fields through a global search of possible environmental parameters. Full Field Inversion Methods in Ocean and Seismo-Acoustics is the formal record of a conference held in Italy in June 1994, sponsored by NATO SACLANT Undersea Research Centre. It includes papers by NATO specialists and others. Topics covered include: . speed and accuracy of acoustic field prediction codes . signal processing strategies . global inversion algorithms . search spaces of environmental parameters . environmental stochastic limitations . special purpose computer architectures . measurement geometries . source and receiving sensor technologies. "

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.

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.

The geodynamic evolution of the Mediterranean region has been often described as a puzzling problem' because of the complex space-time distribution of tectonic events. The gathering of new constraining information and frequent changes of data and ideas among the scientists working on this topic seems to be the most suitable approach to the above problem. This volume reports the most significant results of geological, geophysical, seismological, volcanological, paleomagnetic studies and the geodynamic syntheses presented, and discussed. Special attention is devoted to regions, such as the Aegean--Anatolian and central Mediterranean, which played a crucial role in the evolution of the whole Mediterranean area. A considerable improvement in the understanding of the post-Tortonian deformation pattern of the Tyrrhenian--Apennine system has been achieved by recent geological and geophysical investigations. The geodynamic implications of the data presently available might provide important insights into the evolution of continental collision zones, where shortening processes may also involve lateral extrusion of crustal wedges and consumption of continental-like lithosphere. The main uncertainties which still surround the relative motion between Africa and Eurasia in the Mediterranean region are also pointed out. The arguments reported in this volume are mainly addressed to research scientists and advanced students of the earth sciences. (abstract) This volume reports information about the evolutionary history and the present structural-tectonic setting of the Mediterranean region, which has been presented and discussed during a meeting on Recent Evolution and Seismicity of the Mediterranean Region', held in Erice (Italy) in September 1992. Recent results of geological, geophysical, seismological, volcanological and paleomagnetic studies are described. The geodynamic implications of the presently available data set might provide important insights into the evolution of continental collision zones, where shortening processes may also involve lateral extrusion of crustal wedges and consumption of continental-like lithosphere.

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."

The reasons for writing this book are very simple. We use and teach com puter aided techniques of mathematical simulation and of pattern recogni tion. Life would be much simpler if we had a suitable text book with methods and computer programmes which we could keep referring to. Therefore, we have presented here material that is essential for mathematical modelling of some complex geological situations, with which earth scientists are often confronted. The reader is introduced not only to the essentials of computer modelling, data analysis and pattern recognition, but is also made familiar with the basic understanding with which they can plunge into when solving related and more complex problems. This book first makes a case for seismic stratigraphy and then for pattern recognition. Chapter 1 provides an extensive review of applications of pattern recognition methods in oil exploration. Simulation procedures are presented with examples that are fairly simple to understand and easy to use on the computer. Several geological situations can be formulated and simulated using the Monte Carlo method. The binary lithologic sequences, discussed in Chapter 2, consist of alternating layers of any two of sand, shale and coal."

Intermediate and deep earthquakes in Spain.- Spanish national strong motion network. Recording of the Huelva earthquake of 20 December, 1989.- Regional focal mechanisms for earthquakes in the Aegean area.- Rates of crustal deformation in the North Aegean trough-North Anatolian fault deduced from seismicity.- Regional stresses along the Eurasia-Africa plate boundary derived from focal mechanisms of large earthquakes.- Focal mechanisms of intraplate earthquakes in Bolivia, South America.- Partial breaking of a mature seismic gap: The 1987 earthquakes in New Britain.- Size of earthquakes in Southern Mexico from indirect methods.- Numerical simulation of the earthquake generation process.- Intermagnitude relationships and asperity statistics.- Complete synthetic seismograms for high-frequency multimode SH-waves.- Body-wave dispersion: Measurement and interpretation.

On November 13, 1985, catastrophic mudflows swept down the slopes of the erupting Nevado del Ruiz volcano, destroying structures in their paths. Various estimates of deaths ranged as high as 24,000 residents. Though the nature and extent of risk posed by the mudflows to local communities were well documented before the event and extensive efforts had been made to communicate this information to those at risk, the affected communities were caught largely unaware.
This volume analyzes the disaster's many aspects: the extent, constitution, and behavior of the mudflows; the nature of damage to structures; the status of the area's disaster warning system; and the extent of the area's disaster preparedness, emergency response actions, and disaster relief efforts--both at the time of the disaster and in the first few months following the event.

La Reunion is an oceanic intra-plate volcanic island located at the southern-most part 0 of the Mascarene Basin at 21 0 07' S, 55 32' E (Figure 1). It lies south of the Mascarene Plateau and Mauritius Island but is a distinct topographic feature on the rather flat ocean bottom of the Mascarene Basin, whose age is paleocene in the vicinity of the island (Schlich, 1982), and whose lowest point is more than 4000m deep. La Reunion is ellip tical in shape (50 X 70 km) with a NW-SE elongation. It is composed of two volcanoes: Piton des Neiges and Piton de la Fournaise. A third volcanic structure has been recent ly discovered on the east submarine flank of the island (Unat et aI., submitted). Piton des Neiges, a dormant and deeply eroded volcano, rises to a height of 3069 m and oc cupies the northwestern two-thirds of the island. Piton de la Fournaise (2630 m), one of the most active basaltic volcanoes in the world, began to grow more than 3. 5 X 1O years ago on the southeast flank of Piton des Neiges. The evolution of Piton de la Fournaise (Chevallier and Bachclery, 1981) is marked by the formation of three sub-concentric nested calderas (Figure 2). The boundaries of the two older calderas are more or less buried or eroded."