Analysis of seismotectonic processes in subduction zones from the standpoint of a keyboard model of great earthquakes

Abstract

The block-like structure of the frontal part of the overriding plate in the subduction zones of the Aleutian and Kurile trenches is described. Both block interaction with a subducted plate and reciprocal interblock actions are considered. These interactions are reflected: 1. (1) in the seismic regime; 2. (2) in the distribution of the sources of great earthquakes; 3. (3) in the focal mechanisms of shallow earthquakes. The mechanical keyboard model proposed incorporates these interactions. This model is the basis of a mathematical description of the subsequent slow accumulation of strain and fast seismic release in ajacent blocks in the course of their seismotectonic evolution. Some results of numerical simulations are given. They are in good agreement with the main features of distribution of great earthquakes in space and time for the Kuriles, Japan and Central and South America. “Keyboard” analysis of seismic cycles can be considered as a mechanical basis for long-term prediction of great earthquakes which allows the distinguishing of a number of new earthquake precursors.