Mechanism of Deep-Focus Earthquakes Inferred from High Pressure Experiments

Abstract

Deep-focus earthquakes occur at depths from the earth's surface up to 680 km (corresponding to pressure of 24 GPa). They occur only in the restricted areas in the earth, or the subduction zones. There have been many studies on the nature of the deep-focus earthquakes, but they have not been widely accepted since each model has both advantage and disadvantage to ex -plain the observation facts and the physical, chemical and mechanical properties of rocks and minerals. Recently, two new models are proposed based on the high pressure experiments, together with our understanding of the structure of the subduction zone. One is the transformation faulting (or anticrack faulting) model, and the other is the amorphization model. In this article, these new models inferred from high pressure experiments are reviewed with the brief history of the finding of deep - focus earthquakes and of the studies of their mechanism. © 1993, The Japan Society of High Pressure Science and Technology. All rights reserved.