江苏常熟—太仓5.1级地震的破裂特征及其可能的前兆机制

这次地震前震中附近地区的地震活动随时间呈波浪式起伏,形成了小震条带,出现了小震群;地下水(水位、水温)异常非常强烈;地形变和地磁异常也观测到了.分析发现:前兆不是沿断裂带分布,而主要是位于近震中(≤50km)的破裂面法线方向;震中附近的断裂没有穿过震中.这次地震看来不是沿原有断裂的错动,而是块体内产生新的错动,属于块断型地震,似可用IPE模式解释一些前兆现象.

RUPTURE CHARACTERISTIC OF CHANGSHU -TAICANG EARTHQUAKE (Ms =5.1, 1990) AND ITS MECHANISM OF POSSIBLE PRECURSORS

There were many anomalies near the epicenter area before the Changshu - Taicang earthquake (Ms =5.1, 1990), such as stripes and swarns of microearthquake activity of the flactuation with time, and rapid changes of level and temperature of underground water, and land deformation and geomagnetic anomalies. It is found that the precursors had not distributed a-long rupture zones, but mainly in the normal direction of fracture plane near the epicenter(≥ 50 km), the focus is not on early fracture. It appears that this earthquake was not occurred by dislocation of early fracture, but a new dislocation within block, belonging to block earthquake, so some precursors are interpreted using IPE model.