Spatial distribution and focal mechanism solutions of the Wenchuan earthquake series:Results and implications

查看全文 作　　者：Chen [1]Cai;Chunquan [1,2]Yu;Kai [1]Tao;Xingping [3]Hu;Yuan [1]Tian;Hao [1]Zhang;Xiaofeng [3]Cui;Jieyuan [1]Ning

机构地区：[1]School of Earth and Space Sciences, Peking University, Beijing 100871, China;[2]Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA 01239, USA;[3]Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China

出　　处：《Earthquake Science》索引2011年第24卷第1期,共11页

基　　金：supported by the Wenchuan Fault Scientific Drilling Program(WFSD),the Key Projects in the National Science and Technology Pillar Program during the Eleventh Five-year Plan Period under grant No. 2008BAC38B02-4;the National Natural Science Foundation of China under grant No. 40821062 摘　　要：We relocate the spatial distribution of the devastating 12 May 2008 Wenchuan earthquake and its aftershocks.The relocation database is obtained from 89 stations deployed by the China Earthquake Administration,including 54 525 seismograms from 1 376 local earthquakes over MS3.5 between 12 May 2008 and 3 August 2008.The cross-correlation technique used in this paper has greatly improved the relocation precision by giving much more accurate P-wave differential travel-time measurements than those obtained from routinely picked phase onsets.At the same time,we pick P-wave polarity observations of the Wenchuan earthquake series (hereafter referred to as WES) from 1 023 stations in China and 59 IRIS (Incorporated Research Institutions of Seismology) stations.Then,employing a newly developed program CHNYTX,we obtain 83 well-determined focal mechanism solutions (hereafter referred to as FMSs).Based on spatial distribution and FMSs of the WES,we draw following conclusions:(1) The region near the main shock exhibits a buried low-angle northwest-dipping seismic zone with the main shock at its upper end and two conjugated seismic zones dipping southeast with roughly equal dip-angle;(2) The compressional directions of all kinds of FMSs of the WES are subhorizontal,which reflects the dominant stress in this area is compressional;(3) The principal compressional direction of the regional stress around Wenchuan is roughly perpendicular to the strike of Beichuan-Yingxiu fault,while around Qingchuan it is roughly parallel to the strike of Qingchuan fault.In intermediate part of the Longmenshan area,the principal compressional direction of the stress should be in-between;(4) The possibly existed molten materials in the lower crust of Songpan-Garze terrain have small contribution to the local stress state in Longmenshan area.The listric geometries of the Longmenshan faults most probably resulted from subhorizontal compression along NW-SE direction in history. 关键词：SEISMOTECTONICS stress state RELOCATION focal mechanism solution WENCHUAN

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Spatial distribution and focal mechanism solutions of the Wenchuan earthquake series:Results and implications

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