中国地块的地震应力场

THE SEISMOTECTONIC STRESS FIELD IN THE CHINESE CRATON

摘要:

印度板块往北,菲律宾板块往北西,太平洋板块往南西与欧亚板块碰撞的格局是中国地震构造的决定性因素。根据实地应力测量、地震断层面解、河谷走向和节理产状等不同资料,计算出了由于板块相互作用所形成应力场的方向。计算结果表明:上述板块的碰撞形成了中国境内板内的三大地震构造区,即西部区、华北区、东南区。区内应力是连续的。由于不同区内应力方向有显著不同,这种应力的连续性就必然导致了在其结合部出现应力的不连续,这就是大致沿N40°E的南北地震带。所以南北地震带的出现可能是中国及邻近地区诸板块相互作用的结果。

Abstract:

The seismotectonic conditions in China are determined by the fact that the Eurasian, the Indian, the Philippine and the pacific tectonic plates extend into its vicinity. The Pacific plate pushes from the NE, the Philip-pine plate from the SE and the Indian plate from the S into the Eurasian plate. The intraplate stresses in China are the continuation of the indicated rim stresses. Evidence for their orientation is based on the statistical assessment of in-situ measurements, earthquake fault plane solutions, valley trends and joint orientations. Inasmuch as the direction of the rim stresses is different in various sectors, their continuation into the plate interior must eventually lead to a stress discontinuity:This is the band of the N-S seismic zone at roughly 104°E longitude. Thus, the latter is seen to be a direct consequence of the plate tectonic conditions prevailing in the vicinity of China.