2013年芦山M_S7.0地震震源参数特征及近断层强地面运动初步估计
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摘要
2013年4月20日在我国四川省雅安市芦山县发生了MS7.0地震,破坏最严重的宝兴、芦山等极震区烈度达到Ⅷ—Ⅸ度.该文针对芦山MS7.0地震震源参数的特征,结合相关经验关系,对本次地震的震源特征进行了初步分析.结果表明,芦山MS7.0地震为断层动态摩擦过程中的应力下调模式.进一步应用Brune圆盘模型对芦山MS7.0地震近场强地面运动的理论值进行估算,并基于加速度和速度的估算结果计算极震区的最大烈度,约为Ⅷ—X度,与实测的极震区最大烈度Ⅸ度较为接近.选取宝兴和芦山为特征计算点,构建动态复合震源模型,对近断层区域内宝兴和芦山两个特征点进行了模拟计算.模拟结果显示,近断层区域强地面运动呈现持续时间短、高频成分多等特征.
A MS7.0 earthquake occurred in Lushan County,Sichuan Province of China on 20 April 2013,and the maximum intensity is up to Ⅷ to Ⅸ at Baoxing and Lushan Counties,which are located in the meizoseismal area.This study analyzed the dynamic source process with the source mechanism parameters and empirical relationships,estimated the strong ground motion in the near-fault field based on the Brune's circle model.A dynamical composite source model(DCSM)has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Baoxing and Lushan,respectively.The results indicate that the frictional undershoot behavior in the dynamicsource process of Lushan MS7.0 earthquake is actually different from the overshoot activity of the Wenchuan MS8.0 earthquake.Moreover,the predictions of broadband synthetic seismogram for Lushan and Baoxing shows that the strong ground motion simulation is characterized by large peak values,shorter duartions and more hige-frequency contents,which is affected by higer value of effective stess drop and asperity slip distribution on the fault plane.
A MS7.0 earthquake occurred in Lushan County,Sichuan Province of China on 20 April 2013,and the maximum intensity is up to Ⅷ to Ⅸ at Baoxing and Lushan Counties,which are located in the meizoseismal area.This study analyzed the dynamic source process with the source mechanism parameters and empirical relationships,estimated the strong ground motion in the near-fault field based on the Brune's circle model.A dynamical composite source model(DCSM)has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Baoxing and Lushan,respectively.The results indicate that the frictional undershoot behavior in the dynamicsource process of Lushan MS7.0 earthquake is actually different from the overshoot activity of the Wenchuan MS8.0 earthquake.Moreover,the predictions of broadband synthetic seismogram for Lushan and Baoxing shows that the strong ground motion simulation is characterized by large peak values,shorter duartions and more hige-frequency contents,which is affected by higer value of effective stess drop and asperity slip distribution on the fault plane.
引文
陈学忠,王小平,王林瑛,张天中.2003.地震视应力用于震后趋势快速判定的可能性[J].国际地震动态,(7):1--3.
刘杰,易桂喜,张致伟,官致君,阮祥,龙锋,杜方.2013.2013年4月20日四川芦山M7.0级地震介绍[J].地球物理学报,56(4):1404--1407.
刘启元,李昱,陈九辉,郭彪,李顺成.2009.汶川MS8.0地震:地壳上地幔S波速度结构的初步研究[J].地球物理学报,52(2):309--319.
孟令媛,史保平.2011.应用动态复合震源模型模拟汶川MW7.9地震强地面运动[J].地球物理学报,54(4):1010--1027.
孟令媛,史保平.2012.2011年新西兰MW6.1地震震源过程及强地面运动特征初步分析[J].地球物理学报,55(5):1601--1612.
王卫民,郝金来,姚振兴.2013.2013年4月20日四川芦山地震震源破裂过程反演初步结果[J].地球物理学报,56(4):1412--1417.
张勇,许力生,陈运泰.2013.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,56(4):1408--1411.
Andrews D J.1986.Objective determination of source parameters and similarity of earthquakes of different size[C]∥Das S,Boatwright J,Scholz C H eds.Earthquake Source Mechanics.Washington:AGU:259--267.
Brune J N.1970.Tectonic stress and spectra of seismic shear waves from earthquakes[J].JG eophys Res,75(26):4997--5009.
Brune J N.1971.Correction of"tectonic stress and spectra of seismic shear waves from earthquakes"[J].J Geophys Res,76(20):5002.
Brune J N.1976.The physics of earthquake strong motion[C]∥Lomnitz C,Rosenblueth E eds.Seismic Risk and Engineering Decisions.New York:Elsevier Sci Publ Co:141--177.
Frankel A.1991.High-frequency spectral falloff for earthquakes,fractal dimension of strength on faults[J].J Geophys Res,96(B4):6291--6302.
Hanks T C,Bakun W H.2002.A bilinear source-scaling model for M-logAobservations of continental earthquakes[J].Bull Seismol Soc Am,92(5):1841--1846.
Keilis-Borok V I.1959.On estimation of the displacement in an earthquake source and source dimension[J].Annali di Geofisica,12(2):205--214.
Knopoff L.1958.Energy release in earthquake[J].Geophys J Inter,1(1):44--52.
Orowan E.1960.Mechanism of seismic faulting in rock deformation:A symposium[J].Geol Soc Am Mem,79:323--345.
Savage J C,Wood M D.1971.The relation between apparent stress and stress drop[J].Bull Seismol Soc Am,61(5):1381--1388.
Smith K D,Brune J N,Priestly K F.1991.The seismic spectrum,radiated energy,and the Savage and Wood inequality for complex earthquake[J].Tectonophysics,188(3/4):303--320.
Starr A T.1928.Slip in a crystal and rupture in a solid due to shear[J].Proc Camb Phil Soc,24(4):489--500.
Wald D J,Quitoriano V,Heaton T H,Thomas H,Kanamori H.1999.Relationships between peak ground acceleration,peak ground velocity,and modified Mercalli intensity in California[J].Earthquake Spectra,15(3):557--564.
Wyss M,Brune J N.1968.Seismic moment,stress,and source dimensions for earthquakes in the California-Nevada region[J].J Geophys Res,73(14):4681--4694.
Zeng Y,Anderson J G.1996.A composite source modeling of the 1994Northridge earthquake using genetic algorithm[J].Bull Seismol Soc Am,86(1B):71--83.
Zúiga F R.1993.Fractional overshoot and partial stress drop.Which one?[J].Bull Seismol Soc Am,83(3):939--944.
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刘杰,易桂喜,张致伟,官致君,阮祥,龙锋,杜方.2013.2013年4月20日四川芦山M7.0级地震介绍[J].地球物理学报,56(4):1404--1407.
刘启元,李昱,陈九辉,郭彪,李顺成.2009.汶川MS8.0地震:地壳上地幔S波速度结构的初步研究[J].地球物理学报,52(2):309--319.
孟令媛,史保平.2011.应用动态复合震源模型模拟汶川MW7.9地震强地面运动[J].地球物理学报,54(4):1010--1027.
孟令媛,史保平.2012.2011年新西兰MW6.1地震震源过程及强地面运动特征初步分析[J].地球物理学报,55(5):1601--1612.
王卫民,郝金来,姚振兴.2013.2013年4月20日四川芦山地震震源破裂过程反演初步结果[J].地球物理学报,56(4):1412--1417.
张勇,许力生,陈运泰.2013.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,56(4):1408--1411.
Andrews D J.1986.Objective determination of source parameters and similarity of earthquakes of different size[C]∥Das S,Boatwright J,Scholz C H eds.Earthquake Source Mechanics.Washington:AGU:259--267.
Brune J N.1970.Tectonic stress and spectra of seismic shear waves from earthquakes[J].JG eophys Res,75(26):4997--5009.
Brune J N.1971.Correction of"tectonic stress and spectra of seismic shear waves from earthquakes"[J].J Geophys Res,76(20):5002.
Brune J N.1976.The physics of earthquake strong motion[C]∥Lomnitz C,Rosenblueth E eds.Seismic Risk and Engineering Decisions.New York:Elsevier Sci Publ Co:141--177.
Frankel A.1991.High-frequency spectral falloff for earthquakes,fractal dimension of strength on faults[J].J Geophys Res,96(B4):6291--6302.
Hanks T C,Bakun W H.2002.A bilinear source-scaling model for M-logAobservations of continental earthquakes[J].Bull Seismol Soc Am,92(5):1841--1846.
Keilis-Borok V I.1959.On estimation of the displacement in an earthquake source and source dimension[J].Annali di Geofisica,12(2):205--214.
Knopoff L.1958.Energy release in earthquake[J].Geophys J Inter,1(1):44--52.
Orowan E.1960.Mechanism of seismic faulting in rock deformation:A symposium[J].Geol Soc Am Mem,79:323--345.
Savage J C,Wood M D.1971.The relation between apparent stress and stress drop[J].Bull Seismol Soc Am,61(5):1381--1388.
Smith K D,Brune J N,Priestly K F.1991.The seismic spectrum,radiated energy,and the Savage and Wood inequality for complex earthquake[J].Tectonophysics,188(3/4):303--320.
Starr A T.1928.Slip in a crystal and rupture in a solid due to shear[J].Proc Camb Phil Soc,24(4):489--500.
Wald D J,Quitoriano V,Heaton T H,Thomas H,Kanamori H.1999.Relationships between peak ground acceleration,peak ground velocity,and modified Mercalli intensity in California[J].Earthquake Spectra,15(3):557--564.
Wyss M,Brune J N.1968.Seismic moment,stress,and source dimensions for earthquakes in the California-Nevada region[J].J Geophys Res,73(14):4681--4694.
Zeng Y,Anderson J G.1996.A composite source modeling of the 1994Northridge earthquake using genetic algorithm[J].Bull Seismol Soc Am,86(1B):71--83.
Zúiga F R.1993.Fractional overshoot and partial stress drop.Which one?[J].Bull Seismol Soc Am,83(3):939--944.
①http:∥10.5.160.59/netoffice/module/info/portal/custom/dzj/dzj_news_display.jsp?GeneralID=12007.
①http:∥www.cea-igp.ac.cn/upload/Image/mrtp/tpxw/20130420ds/2668196836.jpg.
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