利用InSAR技术研究2003年西藏班戈MS6.1地震发震构造

2003年7月7日发生在西藏与青海交界处的班戈M_S6.1地震, 由于缺乏余震分布等可靠资料, 其发震构造及其活动性质等问题一直认识不清。 几家机构利用远场波动资料给出的震源机制解差异很大。 本文利用ENVISAT卫星ASAR数据和D-InSAR技术, 计算获得了该地震LOS方向的同震形变场图像, 并以此为约束反演获得了该地震的断层几何参数和同震滑动分布。 结果表明, 班戈M_S6.1地震的发震构造为控制唐古拉山西边界的波涛湖—土门断裂, 其发震断层为走向161°的高角度右旋斜滑正断层, 破裂长度约10 km, 滑动量主要集中在3~7 km深度范围, 最大滑动量0.26 m, 矩震级M_W5.6。

Seismogenic Structure of the 2003 Bange,Tibetan MS6.1 Earthquake Inferred from InSAR Data

Bange M_S6.1 earthquake which occurred on 7 July 2013 at the junction of Tibet and Qinghai province are poorly known in seismogenic structure and active nature due to the lack of aftershock distribution data. Focal mechanism solution given by several angencies using far-field wave data shows huge differences.We utilize descending orbit ENVISAT data and D-InSAR technology to obtain the coseismic deformation image along the LOS of this event, then based on this the fault geometry parameters and coseismic slip distribution are also obtained by seismic inversion.The result shows that the seismogenic tectonic of Bange M_S6.1 earthquake is the Botao lake-Tumen fault which controls the west boundary of the Tanggula Mountain.The earthquake fault is a normal fault with a strike of 161°,high dip angle and right lateral.The length of this ruputure is about 10 km.The slip mainly occurs within 3~7 km along the orientation with a maximum slip of 0.26 m and moment magnitude M_W5.6. The normal fault activity of this earthquake is mainly cause by the EW stretch of the Qiangtang land mass and the right-lateral slip is mainly caused by the difference of the both sides of the Tanggula Mountain’s NE-oriented compressional and shortening.