Relocations and focal mechanism solutions characteristics of 2012 Yiliang MS5.7 and MS5.6 earthquake sequence
LMiaomiao
Ding Zhifeng
Xu Xiaoming
Li Dahu
Ye Qingdong
Zheng Chen
Abstract：Based on the recordings of 17 portable seismographs of ChinArray deployed in Yunnan-Guizhou region,the Yiliang MS 5.7 and MS 5.6 earthquakes happened on September 7,2012 and the aftershocks with ML ≥1.0 were reloca-ted by double-difference hypocenter location algorithm (hypoDD),and then the focal mechanism solutions of earthquakes (MS ≥4.0)were determined by CAP (cut and paste)method.Our results show that the Yiliang MS 5.7 mainshock is located at (27.509°N,103.971°E)with initial rupture depth of 9.7 km.The best double-couple solutions for the Yiliang MS 5.7 earthquake have one nodal plane with strike 251°,dip 66°,rake 150°,and another plane with strike 354°, dip 63°and rake 27°.The Yiliang MS 5.6 mainshock is relocated at (27.563°N, 104.034°E)with initial rupture depth of 10.0 km,and the mechanism solutions of two nodal planes are 235°,39°,147°and 352°,70°,56°,respectively.The fault geometry,aftershock distribution characteristics,focal mechanism solu-tions and the tectonic stress field are in good consistency.Combining with the characteristic of fault kinematic,seismicity and the geological structure,we infer that Yiliang MS 5.7 and MS 5.6 earthquakes occurred on the NE-striking Shimen fault which is the leading edge of Zhaotong fracture.The shallow focal depth of Yiliang earthquake and the energy release occurred in shallow crust are the major reasons for serious damage in the hypocentral region.
Keywords：Yiliang MS 5.7 and MS 5.6 earthquakesdouble difference location methodCAP methodfocal mechanism solution
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 885-898 )