关键词: 地震复发周期, 构造应力场, 有限元模拟

Abstract: The recurrence interval of large earthquake varies from one active fault to another inferred from palaeoseismic data in China. Generally speaking, the interval in eastern part of China is much longer than that in the western part, and that around the plate boundary is remarkably shorter than within the plate of China. To consider the reason for the phenomenon, a mechanical model was constructed by the method of finite element numerical analysis to probe into the distribution of elastic strain energy caused by tectonic stress. The procedures to be used in this paper are:(1) to analyze the boundary condition and action pattern of force on the boundary in China and its adjacent areas by geological method, (2) to make inversion of the force acted on the boundary and the tectonic stress field in the region by finite element method based on the criterion of the maximum principal stress direction, (3) to calculate the attenuation of strain energy with the increase of distance apart from the plate boundary. Based on the attenuation pattern, the accumulative range of strain energy is converted to reach a given value (a given magnitude of large earthquake) in different parts of the research region into time or period, which is compared with the known recurrence interval of large earthquakes along an active fault zone obtained by palaeoseismic method. The comparison shows that the remarkable difference of large earthquake recurrence intervals between plate boundary and plate interior can be well explained by the attenuation pattern of strain energy.

Key words: Earthquake recurrence, Tectonic stress field, Finite elenment modeling