中国东部不同构造区强震前地震非均匀度时间变化特征研究

ON TIME-VARYING FEATURES OF SEISMIC INHOMOGENEOUS DEGREE BEFORE STRONG EARTHQUAKE IN DIFFERENT TECTONIC ZONES OF EASTERN CHINA

基于中国活动地块划分结果,采用地震非均匀度(GL值)预测方法对中国东部(105°E以东)不同构造区自1975年以来的62次4.7级以上地震进行了计算,结果表明,其中大部分地震前1～3年地震非均匀度参数出现明显异常变化,显示出强震前震中及其临近地区的中小地震活动在时间分布上存在着明显的均匀-非均匀的转换,这种变化的出现时间和结束时间与地震所在构造部位有关,区域中小地震活动状态的变化可能是地震孕育到中期或短期阶段震源局部应力场发生变化的一种表象。

We analysed the results of the seismic inhomogeneous degree （ GL value） before the 62 strong earthquakes of magnitudes more than 4.7 distributed in the Eastern China calculated by the regionally small earthquake catalogues based on the result of China active block dividing. The results show that there are obviously abnormal variations of the seismic inhomogeneous degree appeared one to three years before most of the events, and the middle and small seismicity around the epicenter of strong earthquake obviously changes from homogencity to inhomogencity in time distribution before some strong earthquakes. The appearing time and ending time of the state variation before strong earthquakes are related to the tectonic location of the earthquake. The variation of the regionally seismicity state may be the middle-term or short-term behavior of the stress change around the earthquake source.