关键词: 应力状态, 岩石圈流变学, 刚性地块

Abstract: Two necessary conditions for occurrence of great earthquakes,especially for M_S≥8.0 ones are:The high stress which must exceeds the elastic limit of rock;and that the rock should maintain elastic behavior in a longer period than the time for strain accumulation in rock(usually several thousand years).To check the first condition,the actions of the three plates surrounding China are analyzed.The subduction zone between the Pacific plate and Asian plate is far away from the Chinese continent,and the horizontal component of the subduction force is relatively small,so there is no significant effect on China.The collision zone between the Philippine Sea plate and the Asian plate makes Taiwan and Fujian Province of China become high stress area.As the collision boundary is short(only 200km long),the stress declines rapidly along the northwest direction.The high stress area in northwest China and north China is due to the Indian plate's strong collision to Asian plate.The collision boundary between Indian plate and Asian plate is composed of three arc parts with different directions and magnitudes of force.Based on this data,we try to recognize the three seismic belts.To predict the possible locations of great earthquakes,three geologic units(rigid block,sub-rigid block and fold belt)are divided and their rheology is anayzed.Based on the calculated data,the elasticity of rigid block can maintain as long as 1million years,while there is only 1000 years for fold belt.So,the location of M_S 8.0 earthquake is related closely to rigid blocks.

Key words: stress state, lithosphere rheology, rigid blocks