INTRODUCTION

Seismology is a venerable science with a long history. The Chinese scientist Chang Heng is credited with the invention in 132 AD, nearly two thousand years ago, of the first functional seismoscope, a primitive but ingenious device of elegant construction and beautiful design that registered the arrival of seismic waves and enabled the observer to infer the direction they came from. The origins of earthquakes were not at all understood. For centuries these fearsome events were attributed to supernatural powers. The accompanying destruction and loss of life were often understood in superstitious terms and interpreted as punishment inflicted by the gods on a sinful society. Biblical mentions of earthquakes – e.g., in the destruction of Sodom and Gomorrah – emphasize this vengeful theme. Although early astronomers and philosophers sought to explain earthquakes as natural phenomena unrelated to spiritual factors, the belief that earthquakes were an expression of divine anger prevailed until the advent of the Age of Reason in the eighteenth century. The path to a logical understanding of natural phenomena was laid in the seventeenth century by the systematic observations of scientists like Galileo, the discovery and statement of physical laws by Newton and the development of rational thought by contemporary philosophers.

In addition to the development of the techniques of scientific observation, an understanding of the laws of elasticity and the limited strength of materials was necessary before seismology could progress as a science.