中文摘要：

2013年4月20日四川芦山发生了7．0级地震．该地震是自2008年汶川8．0级地震以来发生在龙门山断裂带上的最强地震，截至5月5日，四川省数字遥测台网记录到了52个（M-L，≥4．O）余震．我们搜集了信噪比相对较高的宽频带数据，根据已有的三个分别适合于四川盆地和龙门山断裂东南地区、西南山区、西北山区速度模型，利用TDMT_INVC方法计算矩张量，获得了芦山主震及其16个余震的高质量矩张量解；根据P轴、B轴和T轴的倾角对主震及余震的断层类型进行了分类，结果表明：芦山地震的震级为Mw6．46（矩震级），地震矩为0．61×10-19Nm，震源深度为13km，震源机制类型为逆断层．芦山余震类型简单，主要为逆冲型；芦山地震序列震中分布于龙门山断裂带西南端的彭县一灌县断裂上，本研究获得的主震和余震的震源机制主要为逆冲型，这表明了龙门山断裂西南端主要为逆冲特征．芦山地震震源性质与汶川地震相近，发震间隔时间短，且均发生于同一构造单元内，表明了该地震与汶川地震可能有密切关系．

英文摘要：

On April 20, 2013, the Lushan magnitude 7.0 earthquake occurred in Sichuan, China. It is the largest earthquake occurred on the Longmen Shah fault since 2008 Wenchuan 8. 0 earthquake. Following the mainshock to date May 5, 52 （ML≥4.0） aftershoeks were recorded by the Sichuan Seismic Network. Based on the previous velocity model results respectively for the Sichuan basin and southeast area, southwest mountain area and northwest mountain area, weanalyzed the broadband waveforms for mainshock and aftershock with sufficient signal-to-noise levels to invert for seismic moment tensors. We finally obtained Lushan mainshock and its 16 aftershock moment tensors with the TDMT_INVC method. We sorted the moment tensors based on the plunge of P, B, and T axes. The results show that： the Lushan earthquakePs magnitude is Mw6.5, Mois0.638X1019Nm, depth is 13 km, and focal mechanism is reverse. The type of the aftershocks is simple and mainly as reverse. The Lushan earthquake sequence distributed at the Penxian-Guanxian fault on southwest end of Longmen Shan fault and the focal mechanisms studied in this study mainly as reverse. This phenomenon indicate that the southwest end of Longmen Shan fault mainly as thrust feature. The similar source feature, short occurrence time interval, and located in the same tectonic structure of the Lushan and Wenchuan earthquake, may suggest they have close relationship with each other.