On the physical model of earthquake precursor fields and the mechanism of precursors’ time-space distribution — origin and evidences of the strong body earthquake-generating model

Abstract

According to the requirement of the project “Establishment of the Physical Model of Earthquake Precursor Fields”, this paper elucidates the train of thinking for research on the project and some scientific problems which must be studied; the elucidation emphasizes that the core of this project is to study the conditions and processes of the generation of strong earthquakes. The paper first outlines the origin and development of the “strong-body earthquake-generating model” proposed by the author in the 1980’s; and then proves the reasonableness of the model from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. By studying the tomographic image for the northern part of North China, it can be seen that the sources of strong earthquakes are all distributed in high-velocity bodies, or in the contact zone between high-velocity and low-velocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical models of hard and soft inclusions that the existence of a hard inclusion is an important condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability, sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmental stiffness.