Progress towards an understanding of the dynamics and interactions of galaxies has been spurred on more than ever by a wealth of new observations and numerical experiments. The Heidelberg Conference 1989, the papers of which are collected in this volume, was extremely successful in presenting a synoptic view of the field in all its aspects: galaxy interactions in the early universe and in recent times, interactions of our galaxy and its neighbours, dynamical problems of elliptical and disk galaxies, groups and clusters, starburst and nuclear activity triggered by interactions, merger scenarios, and numerical experiments. Researchers and graduate students, specialists or not, will find here a complete overview of a rapidly growing field of astronomy.

Apart from Hotine's work on Mathematical Geodesy, several previously unpublished reports are collected in this monograph, complemented by extensive comments on these contributions and a complete bibliography of Hotine by the editor.

The African continent is unique in that it has escaped widespread orogenic activity after the Pan African orogenic event. Therefore, the African Plate provides the world's best example of the relationship between extensional magmatism and structural setting. This first complete and up-to-date review, written by leading scientists, discusses the evolutionary model and offers a new and reliable basis for scientists working on plate tectonics and extensional areas in other continents.

The theory, observations, and applications ofgravitational lensingconstitute one ofthe most rapidly growing branches ofextragalactic astrophysics. The deflection of light from very distant sources by intervening masses provides a unique possibility for the investigation of both background sources and lens mass distributions. Gravitational lensing manifestsitselfmost distinctly through multiply imaged QSOs and the formation of highly elongated im ages of distant galaxies ('arcs') and spectacular ring-like images of extra galactic radio sources. But the effects of gravitational light deflection are not limited to these prominent image configurations; more subtle, since not directly observable, consequences of lensing are the, possibly strong, mag nification of sources, which may permit observation of intrinsically fainter, or more distant, sources than would be visible without these natural tele scopes. Such light deflection can also affect the source counts of QSOs and of other compact extragalactic sources, and can lead to flux variability of sources owing to propagation effects. Trying to summarizethe theory and observationalstatus ofgravitational lensing in a monograph turned out to be a bigger problem than any of the authors anticipated when we started this project at the end of 1987, encour aged by Martin Harwit, who originally approached us. The development in the field has been very rapid during the last four years, both through the ory and through observation, and many sections have been rewritten several times, as the previous versions became out of date.

Climate is the most important component of the Earth's environment and climatic fluctuations have a strong impact on water supplies, vegetation, energy use etc. Thus our understanding of the climatic system is of utmost importance. Leading experts in the field of climate modelling and paleoclimatology present the most recent methods for reconstructing past climatic variations and for modelling the climatic system and its evolution. The first of three parts is devoted to the climatic system and the physical basis for its modelling; the second summarizes the evolution of the global atmosphere, the ocean, the continents, the biosphere, and the ice sheets during recent climatic cycles; the last part focusses on the understanding of past and future climatic changes.

This IMA Volume in Mathematics and its Applications STOCHASTIC MODELS IN GEOSYSTEMS is based on the proceedings of a workshop with the same title and was an integral part of the 1993-94 IMA program on "Emerging Applications of Probability." We would like to thank Stanislav A. Molchanov and Wojbor A. Woyczynski for their hard work in organizing this meeting and in edit ing the proceedings. We also take this opportunity to thank the National Science Foundation, the Office of N aval Research, the Army Research Of fice, and the National Security Agency, whose financial support made this workshop possible. A vner Friedman Willard Miller, Jr. v PREFACE A workshop on Stochastic Models in Geosystems was held during the week of May 16, 1994 at the Institute for Mathematics and Its Applica tions at the University of Minnesota. It was part of the Special Year on Emerging Applications of Prob ability program put together by an organiz ing committee chaired by J. Michael Steele. The invited speakers represented a broad interdisciplinary spectrum including mathematics, statistics, physics, geophysics, astrophysics, atmo spheric physics, fluid mechanics, seismology, and oceanography. The com mon underlying theme was stochastic modeling of geophysical phenomena and papers appearing in this volume reflect a number of research directions that are currently pursued in these areas."

This book is written primarily for Earth scientists faced with problems in thermo mechanics such as the flow and evolution of ice-sheets, convection currents in the mantle, isostatic rebound, folding of strata or collapse of cavities in salt domes. Failure, faults, seismic waves and all processes involving inertial terms will not be dealt with. In general such scientists (graduate students beginning a Ph. D. for instance) have too small a background'in continuum mechanics and in numerical computation to model conveniently these problems, which are not elementary at all. Most of them are not linear, and therefore seldom dealt with in treatises. If the study of reality were clearly cut into two successive steps: first to make a physical model, setting up a well-posed problem in thermo-mechanics, and second to solve it, the obvious solution would be to find a specialist in computational mechanics who could spend enough time on a problem which, although maybe crucial for on-going fundamental research, has little practical interest in general, and cannot be considered properly as a noteworthy progress in Mechanics. But this is not the way Science develops. There is a continuous dialectic between the building up of a model and its mathematical treatment. The model should be simple enough to be tractable, but not oversimplified. Its sensitivity to the different components it is made of should be investigated, and more thought is needed when the results contradict hard facts.

Renaissance man " ... discovered many a mechanical marvel .... The achievement of the astronauts '" opened up comparable prospects to the men of today, but of infinitely wider scope". C. LUCET, French Ambassador to the United States.* "Any future ... must inevitably pass through the channel of combined disciplines ... (from which) will arise a humanization of state-of-the-art technology, and updating of methods of Earth Science." Author unknown.** "It is difficult to say what is impossible, for the dream of yesterday is the hope of today and reality tomorrow." ROBERT GODDARD, American physicist. This'phrase has become the symbol of NASA . * Is there a crisis of the spirit?, Bu/. Soc. Prof. Fr. en Amer. (1969) p. 9. *. La recherchespatiale [Space Research] (May 1969) p. 15. INTRODUCTION FROM GALILEO TO ALDRIN AND ARMSTRONG In 1610, Galileo observed the surface of the Moon through the lens which bears his name and announced that, contrary to official opinion, its surface was irregular and not smooth. We now know that this observation -and many others ofGalileo-was a correct one, but the opposition that always arises against research too far ahead of its time resulted in his condemnation.

The NATO Advanced Study Institute "Paleorift Systems with Emphasis on the Permian Oslo Rift" was held at Sundvollen near Oslo, Norway, 26. July - 5. August, 1977. The meeting included 6 field trips to various parts of the Oslo Region. 70 official participants and 16 observers from 14 countries attended the meeting. The majority of the invited lectures, short research papers and progress reports presented at the meeting are published in two volumes, of which this is volume No. II. A table of con tents for both volumes is include8 herein. The field trip guide is being published in the Nor gian Geological Survey Series, Vol. 327 (1978). We are especially pleased to acknowledge the efforts of the many authors of contributed papers, and the able assistance of secretaries, proof-readers and other staffmembers without whose help these volumes would not have been possible. Oslo, 20. February 1978. Ivar B. Ramberg Else-Ragnhild Neumann xi Organizing Committee members: O. Eldholm Department of Geology, University G. Grcentsnlie of Oslo J. Naterstad I.B. Ramberg (chairman) J.A. Dons Mineralogical-Geological Museum, B.T. Larsen (secretary) University of Oslo E.-R. Neumann (secretary) K.S. Heier (chairman) Norwegian Geological Survey S. Huseby B. Sundvoll M.A. Sellevoll Seismological Observatory, University of Bergen K. Storetvedt Geophysics Institute, University of Bergen P.M. Ihlen Geological Institute, University of Chr. Oftedahl Trondheim F.M. Vokes E.S. Husebye NTNF/NORSAR, 2007 Kjeller This volume is Scientific Report No. 40 of the Geodynamics Project

A damaging earthquake with intensity VII MSK and local magni= tude 5. 1 occurred on November 8, 1983, at 0:49 GMT near the Belgium town of Liege in the border region between Belgium, Germany and the Netherlands. This most severe earthquake in the northwestern part of Central Europe since more than thirty years has well been recorded by the dense seismic station network in West Germany which consists of more than twenty stations situated in the Lower Rhine Embayment and in the adjoining Rhenish Massif. Most of the stations are equipped with modern digital recording systems. Thus high-quality seismograms are available from the region east and southeast of the epicenter covering a distance range between 70 km and 144 km. From these data the source characteristics of the Liege mainshock and of its largest after= shock have been determined in order to get more information on the seismotectonic processes causing the Liege events. 2. Seismic Station Network During the period of 1976 to 1982 the seismic station network in the Lower Rhine Embayment and in the Rhenish Massif was consi= derably enlarged and mostly equipped with digital recording systems (Figure 1). At present there are more than twenty stations in operation. Most of them are operated by the Department of Earthquake Geology of the Geological Institute of the University of Cologne and the Geo= logical Survey of Nordrhein-Westfalen at Krefeld.

Physical and chemical studies of the earth and planets along with their surroundings are now developing very rapidly. As these studies are of essentially international charac ter, many international conferences, symposia, seminars and workshops are held every year. To publish proceedings of these meetings is of course important for tracing development of various disciplines of earth and planetary sciences though publishin, g is fast getting to be an expensive business. It is my pleasure to learn that the Center for Academic Publications Japan and the Japan Scientific Societies Press have agreed to undertake the publication of a series "Ad vances in Earth and Planetary Sciences" which should certainly become an important medium for conveying achievements of various meetings to the academic as well as non academic scientific communities. It is planned to publish the series mostly on the basis of proceedings that appear in the Journal of Geomagnetism and Geoelectricity edited by the Society of Terrestrial Magnetism and Electricity of Japan, the Journal of Physics of the Earth by the Seismological Society of Japan and the Volcanological Society of Japan, and the Geochemical Journal by the Geochemical Society of Japan, although occasional volumes of the series will include independent proceedings. Selection of meetings, of which the proceedings will be included in the series, will be made by the Editorial Committee for which I have the honour to work as the General Editor."

This volume contains most of the papers which were presented at the Interdisciplinary Symposium No. 4 "Geodetic Features of the Ocean Surface and their Implications" during the XVIII. General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Hamburg, August 1983. The symposium was jointly sponsored by the International Associ ation of Geodesy (lAG) and the International Association for the Physi cal Sciences of the Ocean (IAPSO), and was as such one further step in animpQrtant line of international and interdisciplinary symposia, re lated to the field of Marine Geodesy. Originally the term "Marine Geodesy" was widely understood as "Geodesy in the Marine Environment" and dealt primarily with two as pects: precise position determination at sea and determination of a fine structured marine geoid. However, mainly with the impact of satel lite radar altimeter measurements, a new understanding began to develop: it became evident that the field of Marine Geodesy could not be treated adequately from geodesists alone but that it needed close cooperation with related disciplines such as oceanography and marine geophysics. Symposium No. 4 at Hamburg could demonstrate that this coopera tion has already become a lively reality. The "geodetic features of the ocean surface" don't only reflect oceanographical but also marine geo physical aspects. As such scientists from geodesy, oceanography, marine geology and geophysics came together to present their ideas and to dis cuss questions of mutual interest."

The ihsan Ketin NATO Advanced Study Institute on the Tectonic Evolution of the Tethyan Region was conceived in 1982 in Veszprem, Hungary, when three of the organizers (B. C. B. , L. H. R. and A. M. C. 9. ) had come together for a meeting on the tectonics of the Pannonian basin. All three of us had experience in the Tethyan belt and all three of us had been for some time deploring the lack of communication among workers of this immense orogenic belt. Much new work had been completed in such previously little-known areas as Turkey, Iran, Afghanistan, the People's Republic of China, the entire Himalayan region, as well as new work in the European parts of the chain. Also, ironically, parts of the belt had just been closed to field work for political reasons, so it seemed as if the time was right to sit back and consider what had been done so far. Because the Istanbul group had had an interest in the whole of the Tethyan belt and because that ancient city was more centrally locElted with excellent opportunities to see both Palaeo- and Neo-Tethyan rocks in a weekend excursion, we thought that Istanbul was a natural place for such a meeting, not mentioning its own considerable attractions for the would-be contributors. A happy coincidence was that Prof.

Proceedings of a Symposium organized by the Summer Advanced Study Institute, held at Queen's University, Kingston, Ontario, August 3-14, 1970

Geophysical prospecting is an applied science and the range of scientific principles to be applied is very wide. In this collection of original papers, the application of many different principles is described in the search for sulphides, other metallic ores and radioactive deposits. The papers are all concerned with surface observations and cover both the theory and the practice of the methods used. In all cases the advan tages and disadvantages of the methods are described and their role in the detection of mineral deposits is discussed and placed in context. Electromagnetic methods are covered in detail, involving the use of both electric and magnetic field effects. Techniques are described involv ing observations both at a number of discrete frequencies and with continuously changing frequency. In spite of the diversity of method it is interesting to note the strong links between the papers; two chapters, for example, start from the same fundamental illustration, first published by Won, of the basic relationship between source frequency, ground con ductivity and depth of penetration. The all-important economic aspects are not forgotten and the first chapter assesses the statistics of performance and describes their use in the shaping and management of an exploration programme. The editor takes this opportunity to thank the busy men who have set aside time to write these contributions."

The promontory of Gargano in the southern Adriatic Sea represents one of the most interesting Italian coastal zones subjected to tsunami hazard. Figure la gives the geographical map of Italy; with a box embracing the region of Gargano; details of that region are in turn sketched in Figure lb. Because of the incompleteness of the earthquake and tsunami catalogues, no reports on tsunamis in this area are available prior to 1600 AD. The Gargano events have been recently revised in order to establish their reliability and to attain the phenomenological reconstruction of the tsunamis (Guidoboni and Tinti, 1987 and 1988; Tinti et. al. , 1995). This work fits the general purpose of assessing tsunami hazard along the Italian coasts and represents a continuation of a previous study, where the first quantitative description of the 1627 tsunami from a numerical modeling viewpoint was performed (Tinti and Piatanesi, 1996). The earthquake took place on 30 July 1627 about mid-day and was followed by four large aftershocks. It claimed more than 5,000 victims and destroyed completely numerous villages in the northern Gargano area, with the most severe damage located between S. Severo and Lesina. The earthquake excited a tsunami with the most impressive effects in proximity of the Lesina Lake where the most reliable contemporary chronicles report about an initial sea water withdrawal of about 2 miles and a subsequent penetration inland.

Advancements in digital sensor technology, digital image analysis techniques, as well as computer software and hardware have brought together the fields of computer vision and photogrammetry, which are now converging towards sharing, to a great extent, objectives and algorithms. The potential for mutual benefits by the close collaboration and interaction of these two disciplines is great, as photogrammetric know-how can be aided by the most recent image analysis developments in computer vision, while modern quantitative photogrammetric approaches can support computer vision activities. Devising methodologies for automating the extraction of man-made objects (e.g. buildings, roads) from digital aerial or satellite imagery is an application where this cooperation and mutual support is already reaping benefits. The valuable spatial information collected using these interdisciplinary techniques is of improved qualitative and quantitative accuracy. This book offers a comprehensive selection of high-quality and in-depth contributions from world-wide leading research institutions, treating theoretical as well as implementational issues, and representing the state-of-the-art on this subject among the photogrammetric and computer vision communities.

The Advanced Study Institute Ice Physics in the Natural and Endangered Environ ment was held at Acquafredda di Maratea, Italy, from September 7 to 19, 1997. The ASI was designed to study the broad range of ice science and technology, and it brought together an appropriately interdisciplinary group of lecturers and students to study the many facets of the subject. The talks and poster presentations explored how basic molecular physics of ice have important environmental consequences, and, con versely, how natural phenomena present new questions for fundamental study. The of lectures discusses these linkages, in order that overall unity of following sunimary the subject and this volume can be perceived. Not all of the lecturers and participants were able to contribute a written piece, but their active involvement was crucial to the success of the Institute and thereby influenced the content of the volume. We began the Institute by retracing the history of the search for a microscopic un derstanding of melting. Our motivation was straightforward. Nearly every phenome non involving ice in the environment is influenced by the change of phase from solid to liquid or vice-versa. Hence, a sufficiently deep physical picture of the melting tran sition enriches our appreciation of a vast array of geophysical and technical problems.

This issue is a collection of the papers read at the 'Workshop on Geomagnetic Observatory and Survey Practice' held during the XIVth General Assembly of IUGG (the International Union of Geology and Geophysics) in Hamburg, August 1983, sponsored by Division V of the International Association of Geomagnetism and Aeronomy (IAGA). The papers represent a snapshot taken at a very important time in the history of Geomagnetism and of the sciences which depend on measurements of one kind or another of the Earth's magnetic field. Research science now demands a much greater amount of information to be prepared and immediately made available to the scientific user. Experimental measurements are now required to be reduced, selected and made ready as information which can be recorded as data on magnetic tape in the form required for direct incorporation into the analytical programmes whiCh individual researchers run on digital computers. Computing has reduced the lead time between when observations are made and when they are required by researchers. Many scientific programmes, particularly those related to Solar-terrestrial geophysics, need data to be analysed as near as possible to the time it is recorded. In Geomagnetism these pressures apply to field variations where satellite based geophysical experiments require high resolution of the fine structure of external disturbance fields, and also to field mapping on a global and local scale where the demand for increased accuracy calls for better absolute observations and more frequent surveys.

The study of sea waves has always been in the focus of mankind's atten tion. This is attributed not only to a desire to understand the behaviour in seas and oceans, but also, it has some practical necessity. Developing up-to date wind wave numerical methods requires detailed mathematical modelling, starting with wave generation, development, propagation and transformation on the surface in different water areas under quasi-stationary conditions, up to a synthesis of climatic features observed under different wave generation conditions in oceans, sea or coastal areas. The present monograph considers wind waves in terms of the most general formulation of the problem as a probable hydrodynamic process with wide spatial variability. It ranges between the global scale of the oceans, whose typical size is comparable with the Earth's radius, to the regional and local scales of the seas, including water areas limited in space with significant current or depth gradients in coastal zones, where waves cease their existence having propagated tens of thousand miles."

This volume tries to summarize the status of observational knowledge of the Kuiper Belt. Its recent discovery has revitalized the astromomical study of the Solar System and is beginning to open new and unexpected windows on the physics of planetesimal accretion. With more and better observational data being obtained at the technological limit of current facilities, a new perception of the relationships that exist among the various classes of small Solar System bodies has emerged. The new observations have also motivated a number of fascinating theoretical studies in Solar System dynamics.

One of the most interesting results obtained in the last two decades in the study of crustal deformation has been the recognition that large regions of continental crust undergo rotations about vertical axis during deformation. Proof of such rotations has come through the paleomagnetic studies, which reveal rotations when paleomagnetic declinations within the deforming region arc compared with those found in coeval rocks in the stable regions outside the deforming zone. Such rotations were first described in Oregon then in the North American Cordilleras and in Southern California and were a surprise to everyone. Even in California which, as a result of oil exploration, was among the best geologically explored regions in the world, no one could claim to have predicted that these rotations would be found. Rotations have subsequently been found in other areas of recent continental tectonic activity, notably in the Basin and Range province, New Zealand, the Andes, Greece and Western Turkey, so that they appear as an important feature of continental deformation.

Many geologists have an equivocal attitude to fluid movements within the crust and the associated changes in the chemical and physical properties of crustal rocks. The controversies earlier this centuary between the "soaks" and the "pontiffs" memorably summarised by H. H. Read (1957) in The Granite Controversy have largely been resolved. Few would now advocate the formation of large granitic bodies by in situ transformation of pre-existing crust as the result of the passage of ichors without the formation of a granitic melt. To many geochemists fluid transport and metasomatism have become slightly suspect processes which at the most locally disturb the primary geochemical and isotopic signatures. While there is common agreement that there are marked differences in the composition of the lower and upper crust, the role of fluid movement as one of the controls of this differentiation is often neglected in favour of suggested primary differences in the composition of igneous rocks emplaced at different depths. Selective fluid transport however provides many geologists with their livelyhood. Without the secondary concentration of commercially important elements by fluids within the crust the mining industry, geological science and human activities based on their products would be very different.

The idea for organl.zl.ng an Advanced Research Workshop entirely devoted to the Earth rotation was born in 1983 when Professor Raymond Hide suggested this topic to the special NATO panel of global transport mechanism in the Geosciences. Such a specialized meeting did not take place since the GEOP research conference on the rotation of the Earth and polar motion which was held at the Ohio State University (USA) in 1973. In the last ten years, highly precise measurements of the Earth's rotation parameters and new global geophysical data have become available allowing major advance to be made in the under standing of the various irregularities affecting the Earth's rotation. The aim of the workshop was to bring together scientists who have made important contributions in this field during the last decade both at the observational and geophysical interpretation levels. The confe rence was divided into four main topics. The first session was dedicated to the definition, implementation and maintenance of the terrestrial and celestial reference systems. A few critical points have been identified as requiring further improvements: (i) appro priate selection of terrestrial sites recognized for their long term stability, (ii) determination of the relationship between terrestrial and celestial references systems as well as between the various terrestrial ones, (iii) improvment of the theory of a rotating elastic earth (the recently adopted theory needs already some corrections')."