Coseismic vertical deformation of the MS8.0 Wenchuan earthquake from repeated levelings and its constraint on listric fault geometry
Qingliang Wang1, Duxin Cui1, Xi Zhang1, Wenping Wang1, Jinwen Liu1, Kang Tian1, Zhaoshan Song2
1 Second Monitoring Center, China Earthquake Administration, Xi’an 710054, China 2 First Monitoring Center, China Earthquake Administration, Tianjin 300180, China
Coseismic vertical deformation of the MS8.0 Wenchuan earthquake from repeated levelings and its constraint on listric fault geometry
Qingliang Wang1, Duxin Cui1, Xi Zhang1, Wenping Wang1, Jinwen Liu1, Kang Tian1, Zhaoshan Song2
1 Second Monitoring Center, China Earthquake Administration, Xi’an 710054, China 2 First Monitoring Center, China Earthquake Administration, Tianjin 300180, China
摘要The devastating MS8.0 Wenchuan earthquake ruptured two large parallel thrust faults along the middle segment of the Longmenshan thrust belt. Preseismic and postseismic leveling data indicated the hanging wall of the Yingxiu- Beichuan-Nanba thrust fault mainly presented coseismic uplift with respect to the reference point at Pingwu county town, and the observed maximum uplift of 4.7 m is located at Beichuan county (Qushan town) which is about 100 m west of the fault scarp. The foot wall of the Yingxiu-Beichuan-Nanba thrust fault mainly showed subsidence with maximum subsidence of 0.6 m near the rupture. By employing a listric dislocation model, we found that the fault geometry model of exponential dip angle δ= 88°×[1-exp(-9/h)] with depth of 18 km and uniform thrust-slip of 5.6 m could fit the observed coseismic vertical deformation very well, which verifies the listric thrust model of the Longmenshan orogenic zone.
Abstract:The devastating MS8.0 Wenchuan earthquake ruptured two large parallel thrust faults along the middle segment of the Longmenshan thrust belt. Preseismic and postseismic leveling data indicated the hanging wall of the Yingxiu- Beichuan-Nanba thrust fault mainly presented coseismic uplift with respect to the reference point at Pingwu county town, and the observed maximum uplift of 4.7 m is located at Beichuan county (Qushan town) which is about 100 m west of the fault scarp. The foot wall of the Yingxiu-Beichuan-Nanba thrust fault mainly showed subsidence with maximum subsidence of 0.6 m near the rupture. By employing a listric dislocation model, we found that the fault geometry model of exponential dip angle δ= 88°×[1-exp(-9/h)] with depth of 18 km and uniform thrust-slip of 5.6 m could fit the observed coseismic vertical deformation very well, which verifies the listric thrust model of the Longmenshan orogenic zone.
基金资助:National Key Basic Research 973 project (2004CB418403) and National Natural Science Foundation of China (40974062)
通讯作者:
Qingliang Wang
E-mail: wangql_cea@sina.com
引用本文:
Qingliang Wang, Duxin Cui, Xi Zhang, Wenping Wang, Jinwen Liu, Kang Tian, Zhaoshan Song. Coseismic vertical deformation of the MS8.0 Wenchuan earthquake from repeated levelings and its constraint on listric fault geometry[J]. 《地震学报》英文版, 2009, 22(6): 595-602.
Qingliang Wang, Duxin Cui, Xi Zhang, Wenping Wang, Jinwen Liu, Kang Tian, Zhaoshan Song. Coseismic vertical deformation of the MS8.0 Wenchuan earthquake from repeated levelings and its constraint on listric fault geometry. Earthquake Science, 2009, 22(6): 595-602.