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| Earthquake fault framework and seismotectonics of the Songpan-Garze region since 1900 |
| Jiasheng Zhang1, Weijun Gan1, Minghua Zhang2, Xiongnan Huang1, Feng Liu1 |
1 Institute of Geology, China Earthquake Administration, Beijing 100029, China
2 Development Research Center of China Geological Survey, Beijing 100037, China |
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Abstract Based on 4 781 observed faults (>2 km length) from a 1:200 000 scale digital geologic map and 5 220 recorded seismic events since the year 1900, 993 earthquake faults are identified within the triangular Songpan-Garze study region. The study area is delineated by the nearly EW-trending East Kunlun fault zone to the north, the NW-trending Xianshuihe fault to the south and the NE-trending Longmenshan thrust belt to the east. Seismicity changes along these earthquake faults, spanning four 10-year intervals since 1970, show that following a strong earthquake swarm, which occurred in the Huya area in the mid-1970s, seismic activity increased from north to south, and migrated eastward along each major strike-slip fault zone. GPS observation data before 2008 indicate a displacement rate across the Xianshuihe fault zone to the south of ~6.5-8.6 mm/a, whereas across the East Kunlun fault zone to the north it was ~1.8-2.2 mm/a. The May 12, 2008 MS8.0 Wenchuan earthquake, which occurred in the southeast corner of the study region, was the result of stable, high-speed left-lateral displacement along the Xianshuihe fault zone, and a sharp eastward bend of the fault trend in response to the presence of crystalline rocks in the Kangding area. Therefore, the 110-year established seismotectonic framework of the Songpan-Garze region can be defined by a network of various earthquake faults and the structural relations of the local earthquake activities.
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Received: 15 May 2012
Published: 10 December 2012
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| Fund:the Major Project of Chinese National Program for Basic Research and Development (2008CB425703) and the International Cooperation Ministry of Science and Technology Key Project (2008DFA20700) |
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Corresponding Authors:
Jiasheng Zhang
E-mail: jszhang@public3.bta.net.cn
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| [1] |
Yu Wang, Shengli Ma, Toshihiko Shimamoto, Lu Yao, Jianye Chen, Xiaosong Yang, Honglin He, Jiaxiang Dang, Linfeng Hou, Tetsuhiro Togo. Internal structures and high-velocity frictional properties of Longmenshan fault zone at Shenxigou activated during the 2008 Wenchuan earthquake[J]. Earthquake Science, 2014, 27(5): 499-528. |
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