2013年甘肃岷县M_S6.6地震矩张量反演及发震构造初探
|
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了2013年7月22日甘肃岷县MS6.6地震的矩张量解,并与Harvard大学CMT解进行了比较。最后结合该地区的地质资料和构造背景分析了岷县地震发震成因,对可能的发震断层进行了讨论。
On July 22,2013,the Minxian magnitude 6.6 earthquake occurred beneath the northeast margin of the Tibetan plateau,Gansu,China.The earthquake and its aftershocks caused considerable damages,including more than 95 casualties,2414injuries,and approximately 17.5billion yuan in property damage.More information on the source properties of such events can help to characterize fault the structures,which can contribute to an improved understanding of the hazards associated with future great earthquakes.As of August 28,13:35,aftershocks have been recorded by the Gansu seismology network,including a magnitude 5.6event following the mainshock.We analyzed the broadband waveforms for the mainshock with sufficient signal-tonoise levels to invert for seismic moment tensors.All stations involved in this study are broadband stations situated near the July 22mainshock;data showing such problems as misorientation of horizontal components,mislabeling,and polarity reversal in one or more components(Niu et al.,2010)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 0.016Hz and 0.05Hz.On the basis of the Crust 2.0global 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.To insure the quality of the results of the inversion process,we retained only the station with variance reduction(VR)is≥ 80,and got 6stations for the inversion.After depth iteration,the best solutions obtained at a depth of 8km were 87,13,and 93for double couple(DC),the compensated linear vector dipole(CLVD)component,and VR,respectively,which indicates highquality results.The two panel's strike,dip,and rake of the solution were 195°,54°,and 149°and305°,65°,and 40°respectively.The moment tensor solutions showed considerable reverse features and contained part of the strike-slip component.Geologic survey indicated no surface rupture.Regarding tectonic framework and the aftershock distribution features,our inversion results were essentially consistent with the strike of the Lintan-Tanchang fault,and the aftershock distribution occurred near the fault.This phenomenon indicates that the Lintan-Tanchang fault was the main tectonic trigger for the Minxian magnitude 6.6 earthquake and that the seismogenic fault of the earthquake was a subfault of the Lintan-Tanchang fault.
On July 22,2013,the Minxian magnitude 6.6 earthquake occurred beneath the northeast margin of the Tibetan plateau,Gansu,China.The earthquake and its aftershocks caused considerable damages,including more than 95 casualties,2414injuries,and approximately 17.5billion yuan in property damage.More information on the source properties of such events can help to characterize fault the structures,which can contribute to an improved understanding of the hazards associated with future great earthquakes.As of August 28,13:35,aftershocks have been recorded by the Gansu seismology network,including a magnitude 5.6event following the mainshock.We analyzed the broadband waveforms for the mainshock with sufficient signal-tonoise levels to invert for seismic moment tensors.All stations involved in this study are broadband stations situated near the July 22mainshock;data showing such problems as misorientation of horizontal components,mislabeling,and polarity reversal in one or more components(Niu et al.,2010)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 0.016Hz and 0.05Hz.On the basis of the Crust 2.0global 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.To insure the quality of the results of the inversion process,we retained only the station with variance reduction(VR)is≥ 80,and got 6stations for the inversion.After depth iteration,the best solutions obtained at a depth of 8km were 87,13,and 93for double couple(DC),the compensated linear vector dipole(CLVD)component,and VR,respectively,which indicates highquality results.The two panel's strike,dip,and rake of the solution were 195°,54°,and 149°and305°,65°,and 40°respectively.The moment tensor solutions showed considerable reverse features and contained part of the strike-slip component.Geologic survey indicated no surface rupture.Regarding tectonic framework and the aftershock distribution features,our inversion results were essentially consistent with the strike of the Lintan-Tanchang fault,and the aftershock distribution occurred near the fault.This phenomenon indicates that the Lintan-Tanchang fault was the main tectonic trigger for the Minxian magnitude 6.6 earthquake and that the seismogenic fault of the earthquake was a subfault of the Lintan-Tanchang fault.
引文
[1]Zhu L,Helmberger D V.Advancement in Source Estimation Techniques Using Broadband Regional Seismograms[J].Bull Seism.Soc.Am.,1996,86:1634-1641.
[2]Snoke J A.Clyde and the Gopher:A Preliminary Analysis of the 12May 1990Sakhalin Island Event[J].Seism.Res.Letters,1990,61:161.
[3]Dreger D S,Helmberger D V.Determination of Source Parameters at Regional Distances with 3-component Sparse Network Data[J].J.Geophys.Res.,1993,98(B5):8107-8125.
[4]Hardebeck J L,Shearer P M.Using S/P Amplitude Ratios to Constrain the Focal Mechanisms of Small Earthquake[J].Bull.Seism.Soc.Am.,2003,93:2434-2444.
[5]Ghose S,Hamberger M W.Source Parameters of Moderatesized Earthquakes in Tienshan,Central Asia from Regional Moment Tensor Inversion[J].Geophys.Res.Let.,1990,25:3181-3184.
[6]Dreger D S.Savage B.Aftershocks of the 1952Kern County,California,Earthquake Sequence[J].Bull.Seism.Soc.Am.,1998,89:1094-1108.
[7]Kim S G,Kraeva N.Source Parameter Determination of Local Earthquakes in Lorea Using Moment Tensor Inversion of Single Station Data[J].Bull.Seism.Soc.Am.,1999,89(4):1077-1082.
[8]赵翠萍,陈章立,郑斯华,等.伽师震源区中等强度地震矩张量反演及其应力场特征[J].地球物理学报,2008,51(3):782-792.Zhao C P,Chen Z L,Zheng S H,et al.Moment Inversion of Moderate Earthquakes and the Locally Perturbed Stress Field in the Jiashi Source Region[J].Chinese J.Geophys.,2008,51(3):782-792.(in Chinese)
[9]唐兰兰,赵翠萍,王海涛.2008年新疆乌恰6.8级地震序列震源特征及帕米尔东北缘应力场研究[J].地球物理学报,2012,55(4):1228-1239.Tang L L,Zhao C P,Wang H T.Study on the Source Characteristics of the 2008 MS6.8Wuqia,Xinjiang Earthquake Sequence and the Stress Field on the Northeastern Boundary of Pamir[J].Chinese J.Geophys.,2012,55(4):1228-1239.(in Chinese)
[10]Tan Y,Zhu L,Helmberger D V,et al.Locating and Modeling Regional Earthquakes with Two Stations[J].J.Geophys.Res.,2006,111,B01306,doi;10.1029/2005JB003775.
[11]Dreger D S,Helmberger D V.Determination of Source Parameters at Regional Distances with Three-components Sparse Network Data[J].J.Geophys.Res.,1993,98:8107-8125.
[12]Saikia K S.Modified Frequency-wavenumber Algorithm for Regional Seismograms Using Filon's Quadrature:Modeling of Lg Waves in Eastern North America[J].Geophys.J.Int.,1994,118(1):142-158.
[13]Niu F L,Li J.Component Azimuths of the CEArray Stations Estimated from P-wave Particle Motion[J].Earthquake Science,2011,24(1):3-13.
[14]Bassin C,Laske G,Masters G.The Current Limits of Resolution for Surface Wave Tomography in North America[J].EOS Trans AGU,2000,81:F897.
[15]王周元.甘肃地区地壳分层结构[J].西北地震学报,1984,6(3):84-91.Wang Z Y.Layered Crustal Structure in Gansu Region[J].Northwestern Seismological Journal,1984,6(3):84-91.(in Chinese)
[16]李少华,王彦宾,梁子斌,等.甘肃东南部地壳速度结构的区域地震波形反演[J].地球物理学报,2012,55(4):1186-1197.Li S H,Wang Y B,Liang Z B,et a1.Crustal Structure in Southeastern Gansu from Regional Seismic Waveform Inversion[J].Chinese J.Geophys.,2012,55(4):1186-1197.(in Chinese)
[17]荣代潞,李亚荣.甘肃岷县两次中强地震震源机制研究[J].地震研究,2006,29(4):344-348.Rong D L,Li Y R.Focal Mechanisms of Two Moderate Earthquakes in Minxian,Gansu,in 2003[J].Journal of Seismological Research,2006,29(4):344-348.(in Chinese)
[18]张辉,王熠熙,冯建刚.甘东南地区地壳介质各向异性特征[J]..西北地震学报,2011,33(2):111-115.ZHANG Hui,Wang Yi-xi,FENG Jiang-gang.Seismic Anisotropy in the Crust in Southeastern Area of Gansu Province[J].Northwestern Seismological Journal,2011,33(2):111-115.(in Chinese)
[19]高见,张元生,郭飚,等.甘东南流动台阵微震监测结果[J].地震工程学报,2013,35(1):177-182.Gao J,Zhang Y S,Guo B,et al.Microearthquake Location Determined by Portable Seismic Array Data in Southeast Gansu Province[J].China Earthquake Engineering Journal,2013,35(1):177-182.(in Chinese)
[2]Snoke J A.Clyde and the Gopher:A Preliminary Analysis of the 12May 1990Sakhalin Island Event[J].Seism.Res.Letters,1990,61:161.
[3]Dreger D S,Helmberger D V.Determination of Source Parameters at Regional Distances with 3-component Sparse Network Data[J].J.Geophys.Res.,1993,98(B5):8107-8125.
[4]Hardebeck J L,Shearer P M.Using S/P Amplitude Ratios to Constrain the Focal Mechanisms of Small Earthquake[J].Bull.Seism.Soc.Am.,2003,93:2434-2444.
[5]Ghose S,Hamberger M W.Source Parameters of Moderatesized Earthquakes in Tienshan,Central Asia from Regional Moment Tensor Inversion[J].Geophys.Res.Let.,1990,25:3181-3184.
[6]Dreger D S.Savage B.Aftershocks of the 1952Kern County,California,Earthquake Sequence[J].Bull.Seism.Soc.Am.,1998,89:1094-1108.
[7]Kim S G,Kraeva N.Source Parameter Determination of Local Earthquakes in Lorea Using Moment Tensor Inversion of Single Station Data[J].Bull.Seism.Soc.Am.,1999,89(4):1077-1082.
[8]赵翠萍,陈章立,郑斯华,等.伽师震源区中等强度地震矩张量反演及其应力场特征[J].地球物理学报,2008,51(3):782-792.Zhao C P,Chen Z L,Zheng S H,et al.Moment Inversion of Moderate Earthquakes and the Locally Perturbed Stress Field in the Jiashi Source Region[J].Chinese J.Geophys.,2008,51(3):782-792.(in Chinese)
[9]唐兰兰,赵翠萍,王海涛.2008年新疆乌恰6.8级地震序列震源特征及帕米尔东北缘应力场研究[J].地球物理学报,2012,55(4):1228-1239.Tang L L,Zhao C P,Wang H T.Study on the Source Characteristics of the 2008 MS6.8Wuqia,Xinjiang Earthquake Sequence and the Stress Field on the Northeastern Boundary of Pamir[J].Chinese J.Geophys.,2012,55(4):1228-1239.(in Chinese)
[10]Tan Y,Zhu L,Helmberger D V,et al.Locating and Modeling Regional Earthquakes with Two Stations[J].J.Geophys.Res.,2006,111,B01306,doi;10.1029/2005JB003775.
[11]Dreger D S,Helmberger D V.Determination of Source Parameters at Regional Distances with Three-components Sparse Network Data[J].J.Geophys.Res.,1993,98:8107-8125.
[12]Saikia K S.Modified Frequency-wavenumber Algorithm for Regional Seismograms Using Filon's Quadrature:Modeling of Lg Waves in Eastern North America[J].Geophys.J.Int.,1994,118(1):142-158.
[13]Niu F L,Li J.Component Azimuths of the CEArray Stations Estimated from P-wave Particle Motion[J].Earthquake Science,2011,24(1):3-13.
[14]Bassin C,Laske G,Masters G.The Current Limits of Resolution for Surface Wave Tomography in North America[J].EOS Trans AGU,2000,81:F897.
[15]王周元.甘肃地区地壳分层结构[J].西北地震学报,1984,6(3):84-91.Wang Z Y.Layered Crustal Structure in Gansu Region[J].Northwestern Seismological Journal,1984,6(3):84-91.(in Chinese)
[16]李少华,王彦宾,梁子斌,等.甘肃东南部地壳速度结构的区域地震波形反演[J].地球物理学报,2012,55(4):1186-1197.Li S H,Wang Y B,Liang Z B,et a1.Crustal Structure in Southeastern Gansu from Regional Seismic Waveform Inversion[J].Chinese J.Geophys.,2012,55(4):1186-1197.(in Chinese)
[17]荣代潞,李亚荣.甘肃岷县两次中强地震震源机制研究[J].地震研究,2006,29(4):344-348.Rong D L,Li Y R.Focal Mechanisms of Two Moderate Earthquakes in Minxian,Gansu,in 2003[J].Journal of Seismological Research,2006,29(4):344-348.(in Chinese)
[18]张辉,王熠熙,冯建刚.甘东南地区地壳介质各向异性特征[J]..西北地震学报,2011,33(2):111-115.ZHANG Hui,Wang Yi-xi,FENG Jiang-gang.Seismic Anisotropy in the Crust in Southeastern Area of Gansu Province[J].Northwestern Seismological Journal,2011,33(2):111-115.(in Chinese)
[19]高见,张元生,郭飚,等.甘东南流动台阵微震监测结果[J].地震工程学报,2013,35(1):177-182.Gao J,Zhang Y S,Guo B,et al.Microearthquake Location Determined by Portable Seismic Array Data in Southeast Gansu Province[J].China Earthquake Engineering Journal,2013,35(1):177-182.(in Chinese)
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心