Mythology

To most ancient and medieval people (and to some people even today), an earthquake is an act of God, or some other supernatural power, visited on mankind as punishment for misbehavior. John Milne (1886) summarized various mythological causes such as the squirming of a giant catfish beneath Japan, a frog (Mongolia), a hog (Celebes), or a tortoise (American Indians).

More mechanistic explanations were preferred by Greek writers. Thales of Miletas (around 580 b.c.) suggested that the earth floated on a universal ocean whose storms shook the land (Sachs, 1979). Winds in subterranean caves also were commonly postulated as the cause. Aristotle (340 b.c.) credits Anaxagoras as the originator of this idea. Aristotle recognized an association between some earthquakes and volcanic eruptions. Because volcanic eruptions often included great and violent exhalations of gas, it was logical to suppose that earthquakes preceding the main eruption resulted from the progression of such gases from one underground cavern to another. The next concept was the possibility that collapse of cavern roofs after an eruption generated earthquake vibrations. René Descartes postulated that subterranean gases exploded to cause earthquakes (Geike, 1905).

By the seventeenth century, many descriptions of the effects of earthquakes had been published, probably with exaggeration and other distortions (Deresiewicz, 1982). Displacements of the ground surface were recognized as an effect of earthquakes but were not yet associated with the source of the vibrations.