中国大陆与邻区强震分区活动性及其随时间演化

Great seismic activities by regions in China's mainland and its vicinity and their evolvement with time

根据主要构造分布、震源机制解分布及地震活动状况,将中国大陆及邻区分成20个单元,6个区。利用中国地震局地球物理研究所提供的地震目录,计算近百年来各单元和各区的6级以上强震释放应变能,做出时间滑动后的应变能-时间曲线图,分析认为:(a)中国大陆及邻区百年来的强震活动是一个复杂的时空动态过程,每个区、带有其高、低潮,然而各地区没有统一的地震释放应变能高潮与低潮;(b)强震的活动与平静只是相对而言的,没有绝对的活动或平静;(c)微动态期划分较好的体现了强震活动特征,每个微动态期内至少有一个高潮期,且强震集中在一个主体地区内发生,各微动态期的能量可以有起伏。通过进一步的讨论和分析,提出中国大陆地壳变形主要受三方面因素的控制:(1)印度板块、太平洋板块和菲律宾板块的活动及其变化控制中国强震活动图像的总体格局;(2)大陆地壳结构的非均匀性及其变化影响了主体地区的形态结构;(3)地壳形变的继承性影响强震活动主体地区形成与变迁的过程。

Based on seismicity patterns, tectonic background and gradual seismic changes, the study region, which covers China's mainland and its vicinity is divided into subregions and 20 units. By using the earthquake (Ms>6.0) catalogue of the latest 100 years for the continental region, the strain energy released by earthquakes in each unit and each subregion is calculated. And the curves of the strain energy released by earthquakes changing with time are drawn after slip averaged by time. They indicate that:(a) the released energy of earthquakes in each subregion is characterized by undulation with alternating high and low points and by multi-phases; (b) the active or quiet period is not absolute but relative; (c) it demonstrates that the division of the micro-dynamic periods for seismicity is appropriate. By further analyzing, considering that there are three main factors that affect the change and migration of the major subregions of great earthquakes, they are as follows:(1) movement and its change of the India plate, the Pacific plate and the Philippine plate controls the basic pattern of strong earthquakes in the China's continent and its vicinity. Earthquakes and tectonic movement along the plate boundaries change with time in an uneven manner. Even along the same plate boundary, activity of each section is different from each other;(2) the heterogeneity of the continental crust has effect upon the structure of the major seismic subregions; (3) the inheritance of crust deformation affects the process of formation and migration of the major seismic subregions.