Large earthquakes can deform the earth’s crust permanently, a study of major quakes in northern Chile over the past million years suggests.

This finding challenges a longstanding theory in geology that seeks to explain how energy is spread during earthquakes. First posited in 1910 by Johns Hopkins geologist Harry Fielding Reid after he observed the displacement of the ground following San Francisco’s devastating 1906 earthquake, the elastic rebound theory holds that rock on either side of a fault slowly deforms over time, until it suddenly snaps back into its original shape, causing the quake. Reid’s theory was the first to satisfactorily account for earthquakes, and has ben supported by many GPS measurements, among other evidence.

The Monitor_April 29_2013