Preliminary Study on the Seismotectonics of the 2013 Lushan MS7.0 Earthquake, West Sichuan
详细信息
- 责任者：Zhang Yueqiao (Institute of Geomechanics ; Chinese Academy of Geological Sciences ; Beijing 100081 ; China) ; Dong Shuwen
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(6)
- 关键词：大震 ; great earthquakes ; 孕震构造 ; seismogenic tectonics ; 四川 ; Sichuan Province
- 页码：p.747-758
- 图表：illus., 42 refs.
- 分类号：0500
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
On April 20 , 2013 , an earthquake with a magnitude of Ms7.0shocked the region of Lushan County , Ya’an City , west Sichuan.The epicenter is located in the zone between Shuangshi and Taiping Townships , with a focal depth of about 13～14km.The maximum intensity degree attained IX.Although severe destruction of buildings in the shocked area , field investigation did not find obvious co-seismic surface rupture , except a small quantity of grand fissures with sand liquidation.Integrate analysis of high resolution satellite images , main-and-after shock distribution and focal mechanism shows that this earthquake is an independent reverse faulting event possibly rupturing the southern segment of the Shuangshi-Dachuan fault , along the SW segment of the Longmenshan fault zone.We infer that the main shock may have occurred on a west-dipping ramp ( with dipping angle of 33°～43° ) of a sole décollement beneath the SW Longmenshan , a similar seismotectonic setting of the Wenchuan earthquake.Historically , there recorded at least two earthquakes with magnitude of Ms 6～6.5along the Shuangshi-Dachuan fault , together with the Lushan earthquake , they characterize the fault activity behavior of this fault zone.Insitu stress measurement results show that this earthquake resulted from the brutal release of accumulated crustal stress within the SW segment of the Longmenshan fault zone.
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