Theoretical global seismology / Теоретическая глобальная сейсмология

After every major earthquake, the Earth rings like a large bell for several days. These free oscillations of the Earth are routinely detected at modern broad-band seismographic stations, which are now distributed globally. The eigenfrequencies and decay rates of the vibrations can be measured and used to constrain the radial and lateral distribution of density, seismic wave speed and anelastic attenuation within the interior. The observed amplitudes and phases can likewise be used to infer the origin times, hypocentral locations, seismic moments, and fault geometries of the earthquakes responsible for the excitation. The analysis of the free oscillations of the Earth and the allied normal-mode methods employed in the determination of the Earth's internal structure and the source mechanisms of earthquakes—the topics considered in this book—constitute one of the cornerstones of quantitative seismology. Excellent reviews which summarize the state of progress at two pivotal points in the development of the field are provided by Stoneley (1961), Lapwood & Usami (1981) and Buland (1981). This introduction contains our own brief historical survey of research on terrestrial free oscillations and the associated propagating surface waves, focusing upon the theoretical and observational advances made prior to 1985. More recent developments are described—with little attention to their historical context—in subsequent chapters of the book. <...>