Relocation of Yushu MS7.1 Earthquake Aftershocks and Discussion on Seismogenic Structure
详细信息
- 责任者：Liu Qiaoxia (Geophysical Exploration Center ; China Earthquake Administration ; Zhengzhou 450002 ; China) ; Yang Zhuoxin
- 刊名：Chinese Journal of Geophysics
- 出版年：2012
- 卷期：55(1)
- 关键词：玉树地震2010 ; Yushu earthquake 2010 ; 余震 ; aftershocks ; 孕震构造 ; seismogenic tectonics ; 青海 ; Qinghai Province
- 页码：p.146-154
- 图表：7 illus., 1 table, 21 refs.
- 分类号：0500
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
Using the data recorded by both movable and fixed digital seismic monitoring networks in Qinghai province as well as the latest crustal velocity model determined with seismic wide angle reflection/refraction profile,a part of the Yushu earthquake aftershocks occurred from April 18 to 29,2010,were relocated accurately by means of Hypoinverse-2000 location algorithm.After relocation,the vertical and horizontal average errors are 1.35 km and 4.68 km,respectively and the root-mean-square residual error of the travel time is 0.49s.The focal depth range is 1.48～19.85 km,and the average focal depth is 10.28 km.The results show that the Yushu earthquake aftershocks are mostly distributed along the northern segment of NW-SE trending Garzê-Yushu fault zone,i.e.Yushu-Longbao fault with a length about 97 km.On the two sides of the principal earthquake(micro epicenter),the aftershock distribution presents different characteristics,which may suggest the different structural features.The densest aftershock area with higher strength,which is about 5 km from the main shock and its range is about 20 km,lay on the southeast of the main shock.Until April 29,the southeast of the main shock is still the major area of stress release.During the occurrence of main shock,much of the stress of the main shock rupture zone is released and the regions where the stress is not released became the major areas with aftershocks taking place.Continuous occurrence of aftershocks may have led to the main shock rupture zone connected to each other,and the rupture extended toward the northwest.The seismogenic fault of Yushu main shock and aftershocks is the northern branch of Garzê-Yushu fault zone,i.e.Yushu-Longbao fault,which dips to northeast with high-angle left-lateral strike-slip.The seismogenic fault dip angle and the fault width are different on the two sides of Bangdong.On the east of Bangdong,the dip angle and the fault width are about 83 degree and 12 km respectively while on its west,the fault width is about 6.5 km and the dip angle descends to 60 degree.