2013年4月20日四川芦山7.0级地震震源破裂特征

2013年4月20日四川芦山发生7.0级地震.本文运用反投影远震P波的方法研究了中心频率为1 Hz的芦山地震震源破裂特征.研究结果显示2013年芦山7.0级地震破裂长度约为20 km,震源破裂时间约为26 s.本文认为在芦山地震的开始阶段(0~4 s)震源的破裂是向震中位置两侧进行的.而芦山地震破裂的第二阶段(5~26 s)是单侧破裂.芦山地震最大能量释放区域位于震中以北.本文对比了运用相同方法研究的发生在同一断裂带上的2008年汶川地震震源破裂特征.发现2013年芦山地震和2008年汶川地震有三点相似之处,即,破裂主要沿北东走向的龙门山断裂带发展;最大能量释放区域没有位于震中;能量都是通过多次子事件来释放的,且第二次能量释放是最大能量释放.对比两次地震破裂区域,可以看出芦山地震的破裂区域是在2008年汶川地震破裂区域的西南端发展的.两次地震的破裂区域占了整个龙门山断裂带的三分之二.

Rupture details of the 20 April 2013 Lushan M7.0 earthquake

An M7.0 earthquake struck Lushan, Sichuan, on 20 April 2013. We study the rupture properties around 1 Hz of Lushan earthquake by back-projecting teleseismic P waves. The results show that the rupture length of Lushan earthquake is proximately 20 km and the rupture duration is about 26 s. The results indicate that in the first 4 s Lushan earthquake ruptured bilaterally. The second half of the Lushan earthquake ruptured unilaterally. The biggest energy release area is located north of the epicenter. We compare the rupture details of Wenchuan and Lushan earthquake which occurred on the same fault. There are three commons for two earthquakes. First, the source ruptures along the northeast trending Longmenshan fault zone. Second, the biggest energy release region is off the epicenter. Third, the source includes more than one subevent. The second subevent has the biggest energy release. The total rupture length of the Wenchuan and Lushan earthquakes is about two thirds of the length of Longmenshan fault zone.