太康MS4.6级地震与重力场演化特征探讨

通过精细处理华北南部2009~2012年流动重力观测数据，结合地震测深剖面，分析太康两次地震前后的重力场演化特征及其与断裂活动、地震构造的关系。结果表明，太康地震前，在重力场差分动态图像上表现出四象限特征，是许昌-太康断裂走滑型发震的前兆，重力场的正负异常区对应震源机制解的压缩区和拉张区。段差和点值时序变化图表明，应变累积主要集中在许昌-太康断裂的西段和震中附近，断裂又位于地壳内低速体的上方，两者为太康地震的孕育和发震提供了条件。

Research on Evolution Characteristics of Gravity Field Before and After Taikang MS4.6 Earthquake

Based on finely processed mobile gravity observation data acquired between 2009~2012,along with seismic sounding profiles in southern north China, this paper discusses the evolutionary characteristics of surface gravity changes caused by the Taikang MS4.6 earthquake. The gravity field before the earthquake shows a four-quadrant characteristic, which is the precursor of a strike-slip earthquake on Xuchang-Taikang fault.The positive and negative gravity fields correspond exactly to the compression zone and tension zone of the focal mechanism solutions. The timing diagram of gravity difference and point value shows that the fracture strain accumulates mainly on the west and south of the Xuchang-Taikang fault, where there is a seismic low-velocity body in the crust. The strain accumulated and the different seismic velocity boundary provided conditions for the earthquake.