2018-04-06无为M_L4.1地震震源机制和深度及发震构造研究

Focal Mechanism and Depth and Seismogenic Structure of the Wuwei M_L4.4 Earthquake, April 6, 2018

基于华东地区测震台网记录,采用CAP方法反演2018-04-06无为M L4.1地震的震源机制解和震源深度,利用双差定位方法对2016年以来无为地区发生的地震进行重新定位。结果显示,地震的震源机制解为:节面I,走向120°,倾角57°,滑动角27°;节面Ⅱ,走向15°,倾角68°,滑动角144°;震源深度为12 km。双差定位结果显示,2016年以来无为地区发生的地震位于无为盆地西南边界,沿SE向分布,震中由NW向SE迁移。根据震源机制解和精定位结果推测,无为M L4.1地震的断层面解为节面I,地震可能是在区域背景应力场作用下由无为盆地西南边界底部的SE向断裂运动引起的。

Based on the digital waveforms of the eastern China seismic network, the best double-couple focal mechanism and the depth of the Wuwei ML4.1 earthquake of April 6, 2008 is determined using the CAP method, and the earthquake sequence from 2016 in Wuwei area is relocated using the HypoDD method. The result shows that the best double couple solution of the ML4.1 event is strike 120°, dip 57°, rake 27° and strike 15°, dip 68°, rake 144°, respectively. The depth of the centroid of the Wuwei ML4.1 event is about 12 km. The relocation of the Wuwei earthquake sequence shows it to be distributed along the southwestern boundary of Wuwei basin in the southeast direction, with the earthquake sequence propagated from northwest to southeast. According to the focal mechanism derived using the CAP method and the relocation of earthquake sequence from 2016 in the Wuwei area, we estimate the fault plane solution for Wuwei ML4.1 earthquake is the nodal plane I. Possible, Wuwei ML4.1 earthquake is generated by the movement of the northwesterly fault, which is at the base of the southwestern boundary of the Wuwei basin under regional stress field.