Marine Geophysics

Provides a comprehensive review of techniques used to explore the oceans and examines what geophysical observations reveal about the structure and tectonics of the seabed and the Earth's interior. Exploration of the oceans using geophysical methods has had a profound effect on the way we view the structure of the earth and its behaviour through geological time. Geophysics has also played a vital role in the search for petroleum and other natural resources lying beneath the seabed. This volume looks at: * the means of locating observations accurately and determining in detail the morphology of the sea floor * the powerful seismic techniques for imaging the Earth's interior from shallow coastal areas to deep-sea trenches * the gravity and magnetic fields over the oceans, heat flow, electrical and radiometric methods and measurements in offshore boreholes * geophysical observations on the development of the modern oceans, the structure of their deep basins, and the nature of their aseismic and seismically active margins. This book will be of interest to marine scientists and advanced undergraduates and postgraduates following courses on, or undertaking research in, geophysics, marine geology, oceanography, physical sciences, remote sensing, marine surveying and offshore engineering.

This book is about marine seismic sources, their history, their physical principles and their deconvolution. It is particularly accented towards the physical aspects rather than the mathematical principles of signature generation in water as it is these aspects which the authors have found to be somewhat neglected. A huge amount of research has been carried out by both commercial and academic institutions over the years and the resulting literature is a little daunting, to say the least. In spite of this, the subject is intrinsically very simple and relies on a very few fundamental physical principles, a somewhat larger number of heuristic principles and a refreshingly small amount of blunderbuss mathematics. As such it is still one of those subjects in which the gifted practical engineer reigns supreme and from which many of the important advances have originated. In Chapter 1 of the book, the underlying physics and concepts are discussed, including pressure and wave propagation, bubble motion, virtual images and the factors determining choice of source. In marine reflection seismology, almost all of the seismic data acquired currently is done with either the airgun or the watergun, which rely on the expulsion of air and water respectively to generate acoustic energy. As a consequence, the discussion in this chapter is geared towards these two sources, as is much of the rest of the book.

This book describes the development of ocean sciences over the past 50 years, highlighting the contributions of the National Science Foundation (NSF) to the field's progress. Many of the individuals who participated in the exciting discoveries in biological oceanography, chemical oceanography, physical oceanography, and marine geology and geophysics describe in the book how the discoveries were made possible by combinations of insightful individuals, new technology, and in some cases, serendipity. In addition to describing the advance of ocean science, the book examines the institutional structures and technology that made the advances possible and presents visions of the field's future. This book is the first-ever documentation of the history of NSF's Division of Ocean Sciences, how the structure of the division evolved to its present form, and the individuals who have been responsible for ocean sciences at NSF as "rotators" and career staff over the past 50 years.

An account of some aspects of marine geology and marine geophysics, comprehensible to those at an early stage in their study of geology and to scientists who are not specialists in these fields. There are many biologists, chemists, mathematicians or physicists who work in the laboratory or on board ship with geologists and geophysicists and this book will help them to understand the aims of their colleages' experiments. Wherever possible, without a loss of necessary precision, terminology is deliberately simplified.