In 1760 English natural philosopher and geologist John Michell published in the Philosophical Transactions of the Royal Society LI (1760) "Conjectures concerning the Cause and Observations upon the Phaenomena of Earthquakes." The work also appeared in a separate edition, a kind of early offprint. In this paper Michell "suggested that earthquakes were experienced as seismic waves of elastic compression travelled through the Earth. He was able to estimate both the epicentre and focus of the 1755 Lisbon Earthquake. He may have been the first to suggest that a Tsunami is caused by a subterranean earthquake" (Wikipedia article on John Michell, accessed 03-30-2012).