2016年印尼苏门答腊岛海域MW7.8地震震源运动学特征

根据中国和全球地震台网记录的波形记录，采用W震相矩张量反演、反投影分析及有限断层模型反演方法，研究了2016年3月2日印尼7.8级地震破裂过程，分析讨论印尼地震震源运动学特征.结果表明：此地震为一次对称的双侧破裂走滑型事件，北北东─南南西向的断层节面（走向5°/倾角85°）为发震断层面.标量地震矩约6.19×10²⁰ Nm，矩震级为7.79，最大的滑动量约11 m，位于破裂起始点北东，沿着断层走向约30 km处.破裂平均速度2.0~2.2 km·s^-1，破裂持续时间35 s，破裂在5~25 s内释放的能量，约占总能量的97%.最终形成了总长度90 km左右的断层.印尼地震具有破裂持续时间短、破裂速度慢、高滑动能量带相对集中等显著特点.本研究对进一步增进海洋岩石圈地震的震源特性认识有重要参考意义.

The kinematic characteristics of the 2016 MW7.8 offshore Sumatra,Indonesia earthquake

We infer the rupture history of the March 2, 2016, M_W7.8 Indonesia earthquake, and further analyze its kinematic characteristics, using seismic waveform inversions, which include W-phase centroid moment tensor inversion, back projection analysis, and finite fault modeling. The selected waveforms are recorded by the China Digital Seismic Network and Global Seismographic Network. The results indicate that this event is considered as a symmetric bilateral rupture source, showing a strike slip faulting. This earthquake occurs on a NNE-SSW trending rupture plane (strike=5°/dip=85°). The total scalar moment is estimated to be 6.19×10²⁰ Nm (or moment magnitude M_W7.79). The peak slip is about 11 m, which is located nearly 30 km northeast of the rupture initiation along the strike direction. The average rupture velocity ranges from 2.0 to 2.2 km·s^-1 and the total duration is about 35 s. The rupture releases majority of the energy during 5~25 s, which is about 97% of the total energy. The rupture develops a fault plane over a length of about 90 km. The Indonesia earthquake has a smaller total duration, a lower rupture velocity and a relatively more compact slip area. This study is helpful to understand the source characteristics of the oceanic lithosphere earthquake.