Topics in Geophysics

Exploration beyond the Earth has tended to overshadow the less spectacular but no less far-reaching and significant efforts to understand our home planet--efforts that have in recent years produced massive quantities of new data and, beyond that, a radically new way of looking at the Earth: a new worldview, a Whole Earth approach, a global concept. As a result, it no longer suffices to update older texts with a scattering of new facts or to write new ones based on older models.This genuinely new text, prepared by the chairman of the geophysics course team at England's Open University, bases itself firmly (but undogmatically) on these new discoveries, in particular on knowledge of the large-scale features of the Earth's surface and interior in both their static and dynamic contexts. This is the global picture of the Earth as perceived by today's Earth scientist, although it carries with it no implication that will necessarily stand for all time without change, or even without radical change. The book opens with a general chapter summarizing this global picture, which is followed by three topics--chapters carefully designed to present three different aspects of geophysics and three different approaches to the science. Among them, they explore the Earth's crust, mantle, and core, but Smith has chosen to examine a few aspects in some detail rather than treat many in passing. This, in a sense, is a case-study text: it is meant for undergraduates, and only simple mathematics is called upon.The first topic is The Earth's Crust and Uppermost Mantle. This typifies the observational branch of geophysics and draws its conclusions from experimental evidence supported by a broad data base.The second treats The Earth's Heat and Thermal Properties, a subject that Smith calls the most important of all branches of geophysics. Nevertheless, the material presented here is not well covered in most texts, at least in part because it represents a speculative approach to geophysics, in the sense that processes that occur deep within the Earth must be inferred from very few clear data, and they may be interpreted in quite different ways.The last topic is Earthquakes: Characteristics, Prediction, and Modification. This is a subject of everyday interest and, in some parts of the world, of day-by-day interest--here, the frames of reference of human time and geological time coincide. Because of its social ramifications, this topical subject might be called an example of applied geophysics.