2010年墨西哥BajaM_W7.2地震与中国玉树M_W6.9地震强地震动特征的对比研究
|
摘要
2010年4月4日墨西哥Baja地区发生MW7.2地震,2人遇难;同年4月14日中国青海省南部玉树地区发生MW6.9地震,截至2010年4月25日,已造成2220人遇难.有报道指出,玉树地震矩震级小于Baja地震,人员伤亡却远大于后者,主要原因在于玉树地区抗震设防标准低、建筑物抗震性能差.地震造成破坏程度的大小并非仅仅取决于矩震级的大小,而同时与其释放的地震波辐射能及发震后造成的强地面运动的大小有关.玉树地震释放的地震波辐射能约相当于Baja地震的10倍,目前玉树地震尚无实测的强震记录.针对玉树地震和Baja地震建立动态复合震源模型,分别模拟基岩上及浅层速度结构(V30,地下30m平均剪切波速)下近断层区域的强地面运动.结果表明,基岩上及V30下玉树地震近断层区域强地面运动整体约相当于Baja地震的2倍.因此,玉树地震造成发震区域内建筑物损毁程度及人员伤亡情况均严重于Baja地震,重要原因之一在于其地震波辐射能大,且强地面运动较强.本文中所应用的动态复合震源模型,在地震矩守恒和地震波辐射能守恒的条件约束下,可以作为地震发生后补充强地面运动数据的有效手段之一.
The 4 April 2010 MW7.2 Baja,Mexico,earthquake occurred in northern Baja California at shallow depth along the principal plate boundary between North American and Pacific plates,and two people were killed in the Mexicalia area.The 14 April 2010 MW6.9 Yushu,China,earthquake occurred as a result of strike-slip faulting in tectonically complex region of the eastern Qingzang plateau.At least 2 220 people were killed in Yushu area till April 25,2010.International media reports of such kind of disasters by Yushu earthquake is resulted from poor building structure design comparing with Mexicalia area.In fact,although the moment magnitude of Yushu event is similar to the Baja event,the radiated seismic energy from Yushu fault dynamic rupture is almost 10 times of the Baja earthquake,resulting stronger near-fault ground motions.In this paper,two special finite fault models with the same size in fault length and width are constructed to simulate the near-fault strong ground motions for comparison study.The fault slip distributions on both faults are generated based on a dynamical composite source model,in which the subevent-source-function is described by Brune's pulse.Our result shows that the near-field peak ground accelerations(PGAs) and peak ground velocities(PGVs) on bed rocks from Yushu event are almost twice as that from Baja event.Moreover,if the shallow velocity structures(V30,average shear-velocity down to 30 m) are considered in the strong motion simulation,the resultant PGAs and PGVs from Yushu event are also twice as that from Baja event.Therefore,the radiated seismic energy plays a significant role in determining the levels of strong ground motions,in which stronger ground accelerations usually cause much more property damages on the ground.The source rupture dynamics related to the frictional overshoot and undershoot is discussed and used to constrain source parameters such as the static stress drop and dynamic stress drop.It needs to point out that,in addition to the moment conservation applied on the main fault,the measurement of radiated seismic energy or apparent stress should be added to the numerical simulation in order to obtain physically realistic result.The numerical modeling developed in this study has a potential application in ground motion estimation/prediction for earthquake engineering purpose.
The 4 April 2010 MW7.2 Baja,Mexico,earthquake occurred in northern Baja California at shallow depth along the principal plate boundary between North American and Pacific plates,and two people were killed in the Mexicalia area.The 14 April 2010 MW6.9 Yushu,China,earthquake occurred as a result of strike-slip faulting in tectonically complex region of the eastern Qingzang plateau.At least 2 220 people were killed in Yushu area till April 25,2010.International media reports of such kind of disasters by Yushu earthquake is resulted from poor building structure design comparing with Mexicalia area.In fact,although the moment magnitude of Yushu event is similar to the Baja event,the radiated seismic energy from Yushu fault dynamic rupture is almost 10 times of the Baja earthquake,resulting stronger near-fault ground motions.In this paper,two special finite fault models with the same size in fault length and width are constructed to simulate the near-fault strong ground motions for comparison study.The fault slip distributions on both faults are generated based on a dynamical composite source model,in which the subevent-source-function is described by Brune's pulse.Our result shows that the near-field peak ground accelerations(PGAs) and peak ground velocities(PGVs) on bed rocks from Yushu event are almost twice as that from Baja event.Moreover,if the shallow velocity structures(V30,average shear-velocity down to 30 m) are considered in the strong motion simulation,the resultant PGAs and PGVs from Yushu event are also twice as that from Baja event.Therefore,the radiated seismic energy plays a significant role in determining the levels of strong ground motions,in which stronger ground accelerations usually cause much more property damages on the ground.The source rupture dynamics related to the frictional overshoot and undershoot is discussed and used to constrain source parameters such as the static stress drop and dynamic stress drop.It needs to point out that,in addition to the moment conservation applied on the main fault,the measurement of radiated seismic energy or apparent stress should be added to the numerical simulation in order to obtain physically realistic result.The numerical modeling developed in this study has a potential application in ground motion estimation/prediction for earthquake engineering purpose.
引文
郭华东,张兵,雷莉萍,张丽,陈玉.2010.玉树地震高倒塌率建筑物及诱因:遥感认识[J].中国科学:D辑,40(5):538--540.
刘超,许力生,陈运泰.2010.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,32(3):366--368.
刘启元,李昱,陈九辉,郭彪,李顺成,王峻,张绪奇,齐少华.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.2011a.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.2011b.有限断层地震波辐射能估算及其在合成强地面运动中的应用[J].地震学报,33(5):637--649.
史保平,孟令媛.2010.基于物理过程的强地表运动预测[G]//10000个科学难题:地球科学卷.北京:科学出版社:563--567.
许力生,邸海滨,冯万鹏,李春来.2010.2010年青海玉树MS7.1地震近断层地面运动估计[J].地球物理学报,53(6):1366--1373.
张勇,许力生,陈运泰.2010a.2010年青海玉树地震震源过程[J].中国科学:D辑,40(7):819--821.
张勇,许力生,陈运泰.2010b.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,32(5):361--365.
Anderson J G.1997.Seismic energy and stress-drop parameters for a composite source model[J].Bull Seism Soc Amer,87(1):85--96.
Andrews D J.1986.Earthquake Source Mechanics[M].American Geophysical Union,Washington,D C:American Geophysical Union Press:37(6):259--267.
Beeler M N,Wong T F,Hickman S H.2003.On the expected relationships among apparent stress,static stress drop,effective shear fracture energy,and efficiency[J].Bull Seism Soc Amer,93(3):1381--1389.
Boatwright J.1982.The dynamic models for far-field acceleration[J].Bull Seism Soc Amer,78(2):1049--1068.
Boore D M,Atkinson G M.2007.Boore-Atkinson NGA Ground Motion Relations for the Geometric Mean HorizontalComponent of Peak and Spectral Ground Motion Parameters[R].PEER report2007/01,Pacific Earthquake Engineering Research Center,Berkeley,California.
Brune J N.1970.Tectonic stress and spectra of seismic shear waves from earthquakes[J].J Geophys Res,75(26):4997--5009.
Brune J N.1971.Correction of“tectonic stress and spectra of seismic shear waves from earthquakes”[J].J GeophysRes,76(20):5002.
Brune J N.1976.The physics of earthquake strong motion[G]∥Lomnitz C,Rosenblueth E,eds.Seismic Risk and Engineering Decisions.New York:Elsevier Sci Publ Co:141--177.
Choy G L,Boatwright J L.2009.Differential energy radiation from two earthquakes in Japan with identical MW:TheKyushu1996and Tottori2000earthquakes[J].Bull Seism Soc Amer,93(3):1815--1826.
Frankel A.1991.High-frequency spectral fall off for earthquakes,fractal dimension of strength on faults[J].J GeophysRes,96(134):6291--6302.
Kanamori H,Brodsky E.2004.The physics of earthquakes[J].Rep Prog Phys,67(8):1429--1496.
González M,Munguía L,Vidal A,Wong V,González M,Suárez F.2001.Two MW4.8Cerro Prieto,Baja California,México,earthquakes on1June and10September1999:strong-motion observations[J].Bull Seism Soc Amer,91(6):1456--1470.
McGarr A,Fletcher J B.2001.A method for mapping apparent stress and energy radiation applied to the1994Northridge earthquake fault zone-revisited[J].Geophys Res Lett,28(18):3529--2532.
Castro R R,Shearer P M,Astiz L,Suter M,Jacques-Ayala C,Vernon F.2010.The long-lasting aftershock series of the3May1887MW7.5Sonora earthquake in Mexican Basin and Range Province[J].Bull Seism Soc Amer,100(3):1153--1164.
Rivera L,Kanamori H.2005.Representations of the radiated energy in earthquakes[J].Geophys J Int,162(1):148-155.
Somerville P G,Graves R W.2003.Characterization of earthquake strong ground motion[J].Pure Appl Geophys,160(10--11):1811--1828.
Wald J D,Allen I T.2007.Topographic slope as a proxy for seismic site conditions and amplification[J].Bull Seism SocAmer,97(5):1379--1395.
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,Yu G.1994.A composite source model for computing realistic synthetic strong ground motions[J].Geophys Res Lett,21(8):725--728.
USGS.2010a.Magnitude7.2-Baja California,Mexico[EB/OL].2010-04-04[2010-05-30].http:∥earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/ci14607652.php.
USGS.2010b.Magnitude6.9-Southern Qinghai,China[EB/OL].2010-04-13[2010-05-30].http:∥earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010vacp.php.
CESMD.2010.Calexico(Sierra EI Mayor)area earthquake of04Apr2010[EB/OL].2010-04-04[2010-05-30].http:∥www.strongmotioncenter.org/cgi-bin/CESMD/iqr_dist_DM2.pl?IQRID=Calexico_04Apr2010&SFlag=0&Flag=2.
刘超,许力生,陈运泰.2010.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,32(3):366--368.
刘启元,李昱,陈九辉,郭彪,李顺成,王峻,张绪奇,齐少华.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.2011a.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.2011b.有限断层地震波辐射能估算及其在合成强地面运动中的应用[J].地震学报,33(5):637--649.
史保平,孟令媛.2010.基于物理过程的强地表运动预测[G]//10000个科学难题:地球科学卷.北京:科学出版社:563--567.
许力生,邸海滨,冯万鹏,李春来.2010.2010年青海玉树MS7.1地震近断层地面运动估计[J].地球物理学报,53(6):1366--1373.
张勇,许力生,陈运泰.2010a.2010年青海玉树地震震源过程[J].中国科学:D辑,40(7):819--821.
张勇,许力生,陈运泰.2010b.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,32(5):361--365.
Anderson J G.1997.Seismic energy and stress-drop parameters for a composite source model[J].Bull Seism Soc Amer,87(1):85--96.
Andrews D J.1986.Earthquake Source Mechanics[M].American Geophysical Union,Washington,D C:American Geophysical Union Press:37(6):259--267.
Beeler M N,Wong T F,Hickman S H.2003.On the expected relationships among apparent stress,static stress drop,effective shear fracture energy,and efficiency[J].Bull Seism Soc Amer,93(3):1381--1389.
Boatwright J.1982.The dynamic models for far-field acceleration[J].Bull Seism Soc Amer,78(2):1049--1068.
Boore D M,Atkinson G M.2007.Boore-Atkinson NGA Ground Motion Relations for the Geometric Mean HorizontalComponent of Peak and Spectral Ground Motion Parameters[R].PEER report2007/01,Pacific Earthquake Engineering Research Center,Berkeley,California.
Brune J N.1970.Tectonic stress and spectra of seismic shear waves from earthquakes[J].J Geophys Res,75(26):4997--5009.
Brune J N.1971.Correction of“tectonic stress and spectra of seismic shear waves from earthquakes”[J].J GeophysRes,76(20):5002.
Brune J N.1976.The physics of earthquake strong motion[G]∥Lomnitz C,Rosenblueth E,eds.Seismic Risk and Engineering Decisions.New York:Elsevier Sci Publ Co:141--177.
Choy G L,Boatwright J L.2009.Differential energy radiation from two earthquakes in Japan with identical MW:TheKyushu1996and Tottori2000earthquakes[J].Bull Seism Soc Amer,93(3):1815--1826.
Frankel A.1991.High-frequency spectral fall off for earthquakes,fractal dimension of strength on faults[J].J GeophysRes,96(134):6291--6302.
Kanamori H,Brodsky E.2004.The physics of earthquakes[J].Rep Prog Phys,67(8):1429--1496.
González M,Munguía L,Vidal A,Wong V,González M,Suárez F.2001.Two MW4.8Cerro Prieto,Baja California,México,earthquakes on1June and10September1999:strong-motion observations[J].Bull Seism Soc Amer,91(6):1456--1470.
McGarr A,Fletcher J B.2001.A method for mapping apparent stress and energy radiation applied to the1994Northridge earthquake fault zone-revisited[J].Geophys Res Lett,28(18):3529--2532.
Castro R R,Shearer P M,Astiz L,Suter M,Jacques-Ayala C,Vernon F.2010.The long-lasting aftershock series of the3May1887MW7.5Sonora earthquake in Mexican Basin and Range Province[J].Bull Seism Soc Amer,100(3):1153--1164.
Rivera L,Kanamori H.2005.Representations of the radiated energy in earthquakes[J].Geophys J Int,162(1):148-155.
Somerville P G,Graves R W.2003.Characterization of earthquake strong ground motion[J].Pure Appl Geophys,160(10--11):1811--1828.
Wald J D,Allen I T.2007.Topographic slope as a proxy for seismic site conditions and amplification[J].Bull Seism SocAmer,97(5):1379--1395.
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,Yu G.1994.A composite source model for computing realistic synthetic strong ground motions[J].Geophys Res Lett,21(8):725--728.
USGS.2010a.Magnitude7.2-Baja California,Mexico[EB/OL].2010-04-04[2010-05-30].http:∥earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/ci14607652.php.
USGS.2010b.Magnitude6.9-Southern Qinghai,China[EB/OL].2010-04-13[2010-05-30].http:∥earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010vacp.php.
CESMD.2010.Calexico(Sierra EI Mayor)area earthquake of04Apr2010[EB/OL].2010-04-04[2010-05-30].http:∥www.strongmotioncenter.org/cgi-bin/CESMD/iqr_dist_DM2.pl?IQRID=Calexico_04Apr2010&SFlag=0&Flag=2.
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