Some Discussions on the Earthquake Occurrence from the Standpoint of Fracture Theory

Abstract

Some important features of earthquake phenomena seem to be well explained by the assumption that earthquakes are elastic waves accompanying brittle fracture of the earth's crust which is not uniform in structure. From the standpoint of this fracture-model of earthquake, the following topics are discussed on the basis of laboratory experiments : the space distribution of the seismic activity, the magnitude-frequency relation of earthquakes, and the patterns of the earthquake sequence. Then, the mechanical structure of the earth's crust in and near Japan is deduced from the space distribution of various patterns of earthquake sequences.