关键词: 地壳介质, 流变性, 震源深度, 脆韧性转换带, 孕震模型

Abstract: Based on the analyses of focal depth distribution in mainland China, we studied the physical features of the crustal media, especially the rheological features of the crustal rocks, and set up a related seismogenic model to reveal the earthquake development environment and explain the mechanism of focal depth distribution. Geothermal results are used to deduce the depth of the brittle-ductile transition zone in the crust of East China and West China, which shows that the depth is about 20～25km in East China and 35～45km in West China. The depths are respectively consistent to the lower limits of the focal depths in East China and West China, which indicates that the continental earthquakes in China terminate at the depth of the brittle-ductile transition zone. According to the deduced results, the brittle-ductile transition zone in the crust would control the distribution of focal depths. A focal model is developed to simulate the continental strong earthquakes, and to explain the mechanism and processes of earthquake development in continental areas.

Key words: Crustal media, rheology, focal depth, brittle-ductile transition zone, seismogenic model