Rupture Process of Subduction-Zone Earthquakes

This review is primarily concerned with the rupture process of large subduction-zone earthquakes determined by various seismological methods, and with its interpretation in terms of an asperity model. It is not possible to make a thorough and extensive review on the subject because of the limited length. Consequently, this review is inevitably biased toward the works in which I was directly involved through collaborations with various investigators. The distribution of large earthquakes along subduction zones has a distinct pattern. Great earthquakes occur in South America, Alaska, the Aleutians, and Kamchatka. In contrast, earthquakes along the Marianas are smaller. The seismicity in other subduction zones is intermediate between these two groups (see Figure 1). Although this regional variation now generally accepted, it was not until an appropriate method for quantification of large earthquakes was developed that the regional variation was clearly recognized. In view of its fundamental importance in seismology, we first review the quantification method.