Amounts and styles of coseismic deformation along the northern segment of surface rupture, of the 2008 Wenchuan Mw 7.9 earthquake, China
Amounts and styles of coseismic deformation along the northern segment of surface rupture, of the 2008 Wenchuan Mw 7.9 earthquake, China
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DOI：
10.1016/j.tecto.2009.09.023
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发表时间：
2010-08
期刊：
影响因子：
2.9
通讯作者：
Chuanyou Li;Zhanyu Wei;Jian-qing Ye;Yongbing Han;Wenjun Zheng
中科院分区：
文献类型：
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作者：
Chuanyou Li;Zhanyu Wei;Jian-qing Ye;Yongbing Han;Wenjun Zheng
2008年5月12日汶川7.9级地震沿着龙门山逆冲断裂带发生，地表破裂超过200 km。现场调查表明，这次地震还破裂了北方段（从北川到青川），沿着沿着，75- 95公里长的活动证据以前很少被发现。这种破裂通常表现为相对简单的1- 6米高的陡坎，沿顶部沿着有褶皱和拉伸裂缝，上壁和下盘都有轻微变形。沿该段测得的最大垂直位移和右旋位移沿着分别为9.0 m和3.0 m。垂直同震位移量由西南向东北逐渐减小，而右旋位移量则向破裂东北端逐渐增大。表面破裂明显终止于东北端，主要为走滑断层。可观测到的破裂带长约75 km，位于北川-水关之间，以逆冲滑动为主，兼有右旋走滑成分，倾向北西，倾角54-84°。沿着该段的地表变形可分为五种特征类型，从单纯逆冲、逆冲+右行滑动到单纯右行滑动。缩短量估计较小，0.2- 1.0 m。
The May 12, 2008, Mw 7.9 Wenchuan earthquake occurred along the Longmen Shan fault zone, a thrust fault zone on the eastern margin of Tibet Plateau, and ruptured the ground surface for more than 200km. A field investigation suggests that the earthquake also ruptured the northern segment (from Beichuan to Qingchuan), along which active evidence had been less identified before, 75–95km long. This rupture commonly presents a relatively simple 1- to 6-m-high scarp with folding and tension cracks along the crest and with minor deformation on both the hanging wall and the footwall. The maximum measured vertical and dextral displacements along this segment are 9.0m and 3.0m, respectively. The amounts of the vertical coseismic displacements decrease from southwest to northeast, but the amounts of the dextral displacements increase toward the northeastern end of the rupture. The surface rupture apparently terminates as mainly strike-slip faulting at the northeastern end. The observable rupture zone is about 75km long, between Beichuan and Shuiguan, showing mainly thrust slip, with a component of dextral strike-slip, dipping NW at an angle of 54–84°. The surface deformation along this segment is classified into five characteristic styles that range from pure thrusting, a mixture of thrust and dextral slip, to pure dextral slip. The amount of shortening is estimated to be minor, 0.2–1.0m.