摘要
使用甘肃省测震台网记录的三分向宽频带长周期数字波形资料,在时间域反演2012年5月3日甘肃金塔5.4级地震的矩张量解,并与Harvard大学CMT解进行比较。结合该地区的地质资料和构造背景,分析金塔地震的发震成因。结果显示震源性质为走滑型,断层破裂面走向为166°、倾角66°、滑动角-168°,P轴走向为32°,与金塔地震余震分布和地震破坏分布情况大体一致,由此推测金塔地震的发震断层可能为神螺山-野马井断层。
On May 3,2012,the Jinta MS5.4earthquake occurred beneath the northeast margin of the Tibetan Plateau,Gansu,China.We analyzed the broadband waveforms for the mainshock with sufficient signal-to-noise levels to invert for seismic moment tensors.All stations involved in this study are broadband stations situated near the May 3mainshock;data showing such problems as misorientation of horizontal components,mislabeling and polarity reversal in one or more components were removed.During the data processing,we removed the mean value and instrument response,detrended the waveforms,integrated the three-component velocity waveforms to displacement,and rotated the horizontal components to the radial and tangential directions.Before performing moment tensor inversion,waveforms were filtered with a Butterworth Filter with frequencies between 0.016 Hz and 0.05 Hz.On the basis of the Crust 1.0global crustal model,and considering the heterogeneity of the crust and the distances to the recording stations,various velocity models for each station were employed to account for variabilities in the crustal structure.During the inversion process,to insure the quality of the results,we retained only the station with variance reduction（VR）is≥ 80,and got 5stations for the inversion.After depth iteration,the best solutions obtained at a depth of 12 km were 71,29,and 91.5%for double couple（DC）,the compensated linear vector dipole（CLVD）component,and VR,respectively,which indicates high-quality results.The two panel＇s strike,dip,and rake of the solution were 166°,66°,-168°and 71°,79°,-25°respectively.It is found that our inversion results are basically consistent with the strike of the Shenluoshan-Yemajing fault,and the aftershocks distribution occurred near the fault.Associating with the tectonic framework,damage characteristics,and the aftershock distribution feature,we suggest that Jinta MS5.4earthquake was caused by the combined action of southeast Mashan fault and Shenluoshan-Yemajing fault,and the latter should be the seismogenic fault of the earthquake.
出处
《地震工程学报》
CSCD
北大核心
2015年第4期1124-1128,共5页
China Earthquake Engineering Journal
基金
地震行业科研专项课题(201208009)
关键词
金塔5.4级地震
矩张量反演
Jinta MS5.4 earthquake
moment tensor inversion
