2013年甘肃岷县-漳县6.6级地震烈度异常点分布及成因

Abnormal earthquake intensity points and its mechanism of the Minxian-Zhangxian M_S6.6 earthquake on July 22,2013,Gansu

2013年7月22日甘肃岷县-漳县Ms6.6地震发生在临潭-宕昌断裂的东段,遥感和DEM研究表明,该断裂东段在晚第四纪以来仍有活动,自岷县至宕昌,断裂由左旋走滑兼具逆冲性质转为以左旋走滑性质为主。现场烈度和灾害调查发现,Ⅶ度区内形成Ⅷ度的异常点,在Ⅵ度区内形成Ⅶ度的异常点,这些异常点分布在沿断裂带附近约2km的范围内,主要分布在断层的上盘。进一步研究表明,由于临潭-宕昌断裂在岷县以南以走滑运动为主,强震动主要沿断裂传播,同时由于断裂活动形成软弱地基,强震动引起地基失效造成灾害,形成了烈度异常点。

On July 22,2013,the Minxian-Zhangxian MS6. 6 earthquake occurred on the east segment of Lintan-Dangchang fault. The analysis of digital elevation and remote sense image shows that the east segment of Lintan-Dangchang fault is still active and the main thrust feature of the fault switches to left lateral slip. With the field research of intensity and damages,several abnormal points of 8 degree spread in isoseismal line of 7 degree and some abnormal points of 7degree spread in isoseismal line of 6 degree. These abnormal points distribute along the hanging wall of the fault in width of 2km. The analysis based on remote sense and digital elevation model shows that the segment of the Lintan-Dangchang fault south Minxian mainly slips in left literal.The fault movement made the soil soft in the fault zone. The earthquake motion propagates along the fault zone. The strong earthquake motion causes foundation failure in the soft soil along the fault zone and the abnormal intense points of disaster formed.