论文部分内容阅读
2008年5月12日汶川M_s8.0级特大地震发生后,在北川县擂鼓地区出露了一条擂鼓同震地表破裂带,该破裂带呈近南北向展布,位于映秀-北川断裂的中北段,其北东起于擂鼓镇柳林村北部,南西止于石岩村南部,以脆性破裂为特征,分别由3条呈北北东、北西西、北北东走向的地表破裂组成,延伸长度约4～5km,并切割了多种地貌单元,其平均垂直断距为1.5m,平均水平断距为1.4m,垂直与水平断距之比为1.07:1。通过对该地表破裂带野外测量数据、几何展布结构及其成因机制的初步分析表明:擂鼓断裂是出露于擂鼓地区的捩断层,具有捩断层的基本特性;其主要特征包括:1)擂鼓断裂的形成是由于在汶川地震中其东西两侧逆冲块体之间的差异性运动而引起;2)断裂呈近南北向展布,与映秀-北川主干断裂近垂直相交;3)断面倾角较陡,为高角度断面的逆断层,具有逆冲兼走滑特征。
After Wenchuan M_s8.0 Earthquake on May 12, 2008, a surface rupture zone of the Leigu coseismic anomaly was revealed in the Leigu area of Beichuan County. The rupture zone spreads nearly north-south and is located at Yingxiu-Beichuan fault The north-central segment starts from the north of Liulin Village in Leigu Town, and ends in the south of Shiyan Village. It is characterized by brittle failure, and consists of three surface ruptures, each of which runs north and east, north and west, north and north east. The extension is about 4 ~ 5km in length and cut into various geomorphological units. The average vertical distance is 1.5m, the average horizontal distance is 1.4m and the ratio of vertical to horizontal distance is 1.07: 1. The preliminary analysis of the data of the surface rupture zone and its geometric distribution and its genetic mechanism shows that the ruigu rupture is a 出 fault exposed in the Leigu area and has the basic characteristics of the 捩 fault. Its main features include: 1 ) The formation of the drumming drum rupture is caused by the differential motion between the thrust blocks on both sides of the Wenchuan earthquake; 2) the fracture is nearly north-south and nearly perpendicular to the Yingxiu-Beichuan main fault; 3 ) The steep dip of the section is the reverse fault of the high-angle section, which has the characteristics of thrusting and strike-slip.