Seismogenic Structure of the April 20, 2013, Lushan Ms7 Earthquake in Sichuan |
| |
Authors: | ZHANG Yueqiao DONG Shuwen HOU Chuntang SHI Jusong WU Zhonghai LI Hailong SUN Ping LIU Gang LI Jian |
| |
Institution: | ZHANG Yueqiao 1 , DONG Shuwen 2 , HOU Chuntang 1 , SHI Jusong 1 , WU Zhonghai 1 , LI Hailong 1 , SUN Ping 1 , LIU Gang 2 and LI Jian 1 1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081 2 Chinese Academy of Geological Sciences, Beijing 100037 |
| |
Abstract: | At 08:02 on April 20, 2013, a Ms7.0 earthquake occurred in Lushan, Ya'an, in the Longmenshan fault zone, Sichuan. The epicenter was located between Taiping Town and Shuangshi Town, Lushan County and the maximum earthquake intensity at the epicenter reached class IX. Field investigations in the epicenter area found that, although buildings were seriously damaged, no obvious surface rupture structure was produced, only some ground fissures and sand blows and water ejection phenomena being seen. An integrated analysis of high‐resolution remote sensing image interpretation, mainshock and aftershock distribution, and focal mechanism solutions indicated that this earthquake was an independent rupturing event in the southwestern segment of the Longmenshan fault zone, belonging to the thrust‐type earthquake. Ruptures occurred along the south‐central segment of the Shuangshi‐Dachuan fault and the principal rupture plane dipped SW at 33–43°. It is inferred that the Lushan earthquake might be related to the ramp activity of the basal detachment zone (13–19 km) of the Longmenshan fault zone. Historically, there occurred at least two Ms6–6.5 earthquakes along the Shuangshi‐Dachuan fault zone; thus it is thought that the Lushan earthquake, different from the Wenchuan earthquake, was a characteristic one in the southwestern segment of the Longmenshan fault zone. In‐situ stress measurements indicated the Lushan earthquake was the result of stress release of the southwestern segment of the Longmenshan fault zone after the Wenchuan earthquake. This paper analyzes the tectonic setting of the seismogenic structure of this earthquake. |
| |
Keywords: | Lushan Shuangshi‐Dachuan fault Longmenshan fault zone ground fissure thrust ramp Sichuan |
本文献已被 CNKI 等数据库收录! |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
|