【摘要】 北京时间2013年7月22日上午7:45分,甘肃省定西市岷县、漳县交界地区（34.5°N,104.2°E）发生了里氏6.6级地震,引发山体滑坡等地质灾害,造成了严重的人员伤亡和经济损失.本研究基于有限断层模型反演方法,利用远震P波数据（2 Hz）和SH波数据（1 Hz）反演得到了此次地震的震源破裂过程.其中,为了对数据的高频信息进行分析,我们改进了传统的震源时间函数,采用混合震源时间函数（包含高频和低频信息）对地震震源进行描述.研究发现,通过改进的震源时间函数,反演过程中数据的高频信息得到了很好的解释,反演结果与观测波形的拟合效果更好.从反演结果来看,此次地震的破裂分量主要以逆冲方式为主,起震深度在6 km左右;在起始破裂处有最大的滑移量,最大滑移量在0.65 m左右,此次地震释放的标量地震矩为1.3×10¹⁸N·m,相当于矩震级为Mw6.1.根据滑动分布推断此次地震的主要应力降发生在震源附近,平均应力降约为1.5 MPa,应力释放相对较小.更多还原

【Abstract】 On July 22,2013 at 7:45 am,a magnitude 6.6earthquake occurred in the border of Min County and Zhang County,Dingxi,Gansu Province,which induces massive landslides,causes great disasters to life and property.Based on the finite fault inversion method,we inverted the rupture process of the Dingxi earthquake using teleseismic P waves（up to 2 Hz） and SH waves（up to 1 Hz）.In addition,in order to analyze the high frequency information of teleseismic data,we improved the traditional source time function,using hybrid source time function（Contains high frequency and low frequency）.The study found that using the improved source time function,the high frequency information of the teleseismic data are well explained,and had a better fitting between synthetic waveforms and observed seismograms.The inversion results indicate that the main shock is dominated by a thrust fault mechanism and the rupture initiated at a focal depth of 6km,most of slip occurred around the hypocenter with the peak slip of more than 0.65 m,The total seismic moment of whole fault is 1.3×10¹⁸ N·m,equivalent to a magnitude Mw 6.1.Using the slip on the fault we compute an average stress drop of1.5 MPa,the stress release is relatively small.更多还原