Seismology in the United States, 1986-1990

Abstract

In this volume, seven highly respected seismologists attempt to summarize seismological research in the U.S. in the past four years. This is indeed a daunting task; the mere compilation and classification of the overwhelming volume of new seismological literature is difficult enough, but to confidently provide an overview of our new knowledge and understanding is almost impossible. Although the study of vibrations in the Earth (that is, seismology) may at first seem to be a scientific field of limited scope, it encompasses a vast range of observations and problems in mathematical physics. Seismologists currently study waves varying in frequencies from 10^2 Hz to 10^(-4) Hz (20 octaves) and in acceleration amplitudes from 1 g to 10^(-12) g (240 dB). These waves are observed at a wide variety of distances as they travel through a very complex medium, the interior of the Earth. Furthermore the waves are excited by numerous and often complex mechanisms, including earthquakes, man-made explosions, landslides, volcanoes, and atmospheric disturbances. Seismologists study waves from earthquakes that range in energy over 15 orders of magnitude. These waves are studied to reveal the physical properties of the Earth, the kinematics and dynamics of Earth deformation, the characteristics of destructive earthquakes and volcanoes, and the occurrence of man-made explosions. When viewed from this perspective, it is little wonder that any individual seismologist can feel overwhelmed by the sheer volume of seismological research in the past four years. Several thousand seismological papers were published in the past four years; Langston (this issue) alone lists 800 papers pertaining to wave propagation problems. I confess that I have only read a small fraction of these, and even if I had read them all, I would not attempt to choose those having the greatest significance. Instead, I can only summarize current trends in seismological research.

Files

Additional details