Geologists study quake subduction zones

NEW HAVEN, Conn., Jan. 31 (UPI) -- Scientists from Yale and the University of Washington say major earthquakes might be caused by the buildup of sediment on top of subduction zones.

The study suggests a new way to forecast the most severe earthquakes.

Subduction zones are areas in which two tectonic plates collide -- one plate pushes over and one pushes under the other. The most severe earthquakes in recent history -- in Indonesia in 2004, Alaska in 1964, Chile in 1960 and the Pacific Northwest in 1700 -- occurred at subduction zone faults.

"Seismologists have long known that the motion of the plates at subduction zones can be smooth and steady in some areas, and sticky and unsteady in other areas," said Mark Brandon, professor of geology and geophysics at Yale and senior author of the study.

Doctoral student Christopher Fuller and Associate Professor Sean Willett at the University of Washington, along with Brandon at Yale, believe they've found a key to identifying specific areas within a subduction zone that will produce the most severe damage when they rupture.

They describe their work in the February issue of the journal Geology.