The Seismogenic Zone of Subduction Thrust Faults

Abstract

This book is essentially B.S.—Before Sumatra. Before December 26, 2004, when part of the thrust fault interface between the subducting Indian and overriding Burma plates off the coast of Sumatra broke. Before the rupture raced 1,200 km northward at 10,000 km/hr (Mach 8). Before an area of the subducting plate comparable to that of California moved 10 meters, causing a magnitude 9.3 earthquake that was the largest in 40 years. Before the resulting seafloor motion generated a tsunami that crossed the Indian Ocean at the speed of a jetliner and killed more than 200,000 people. Is a B.S.—Before Sumatra—book about subduction zones still useful? The almost unbelievable size of this earthquake and its effects brought home how little we still know about the physics of the subduction zone interface where large earthquakes including the rare giant (M 9) earthquakes occur. (As part of efforts to entice students into the earth sciences we might call these “extreme” or “X-quakes.”) Two previous giant earthquakes, off Chile in 1960 and Alaska in 1964, occurred just before the discovery of plate tectonics explained that such earthquakes occur when years of strain …