2011年1月19日安庆ML4．8地震的震源机制解和深度研究

Focal mechanism and focal depth of the 19 January 2011 Anqing earthquake

2011年1月19日在安徽省安庆市辖区与怀宁县交界处发生了ML4.8级地震,引起安庆市及周边地区强烈的震感.为了更好地认识这次地震的发震构造,我们利用安徽省及临近几个省份区域台网的近震波形资料,首先通过hypo2000绝对定位得到震中位置;然后采用CAP方法反演了该地震的震源机制解和震源深度,并在此基础上结合P、sP、pP和sPmP等深度震相对震源深度进行了精确确定;最后,将反演得到的结果作为已知输入,利用F-K方法计算理论地震图,并与观测记录进行对比,以验证结果的可靠性.反演结果显示,这次安庆地震是一个带少量走滑分量的逆冲型地震,地震矩震级为MW=4.3,最佳双力偶解为节面Ⅰ走向131°,倾角30°,滑动角29°;节面Ⅱ走向15°,倾角75°,滑动角116°,最佳震源深度为4～5km,属于浅源地震.从震中和震源机制解来看,安庆地震极有可能发生在宿松-枞阳断裂上.

mechanism and focal depth were determined by the ＂Cut and Paste＂ （CAP） method. In order to better constrain the focal depth, we further refined it with depth phases such as P, sP, pP and sPmP. Finally, the results of focal mechanism and focal depth were confirmed by comparing the observed records and the synthetic waveforms which were computed by F-K method. The results indicate that the Anqing earthquake is a thrust event with a small part of strike-slip component. The best double couple solution is 131~, 30~ and 29~ for strike, dip and slip angles respectively for one nodal plane, and 15~, 75~ and 116~ for another. The moment magnitude is 4. 3, and the estimated focal depth is 4~5 km, which suggests that this event is a shallow earthquake and capable of heavy hazard to the surrounding areas. According to the epicenter and the focal mechanism, Anqing earthquake likely occurred on the Susong-Zongyang Fault.