地震震源与灾害评估分析:中国四川2008年5月12日Ms 8.0汶川地震(英文)
|
摘要
汶川5月12日8.0级地震在构造上起因于印度板块与欧亚板块以每年约5cm的速度聚敛,并因此而引起青藏高原的地壳物质向四川盆地及中国东南大陆运移。主震震源及余震活动集中于以龙门山为中轴的一条长约350km、宽约100km的地震活动带。震源深度一般分布于地壳脆性-韧性转换边界以上约10~20km区间的地壳震源层之中,属浅源构造地震。主要震源机制与龙门山构造运动方式密切相关,以其地壳厚度向西急剧加厚、重力梯度带、高波速比(Vp/Vs~2.2)等深部异常及逆冲断层兼具走滑性质的地质构造为特征。在震源辐射、路径传播和场地效应研究的基础上,分别计算并比较了岩石和土壤条件下的地震响应谱,特别强调了土壤条件下的场地放大效应;同时对与地震安全性有关的一些问题如地质灾害、地震频谱设计、地震早期预警系统及中、长期至短期地震预报等进行了探讨;特别提供了一个由加权平均计算、以岩石条件下震波衰减模式为基础的地震频谱设计参考实例。地震构造与动力学研究可融入工程地质与环境工程等学科发展。经历汶川地震考验的一些新近设计和建设的工程项目可为今后改进工程建筑规范与标准提供重要而有益的参考。地震预报是当今一大难题,但需探索研究,不可懈怠。地震减灾与预防是目前比较切合实际的安全举措。
The May 12, Ms 8.0 Wenchuan earthquake is tectonically due to the convergence of the India plate against the Eurasia plate at a rate of ~50 mm/yr, which resulted in the crustal movement toward the eastern Sichuan Basin and the southeastern China continent from the uplifted Tibetan Plateau. The epicentral area is located in the active Longmenshan centralized seismic zone along which the aftershocks are concentrated within a ~350 km long and ~100 km wide active belt of horizontal projection. Hypocentral depths range generally from ~10 to ~20 km within the crustal seismogenic zone above the brittle-ductile transition boundary, characterized typically by shallow tectonic earthquakes. Focal mechanism of the Wenchuan earthquake bears a close correlation with the Longmenshan tectonic movement indicated by the particular deep structural anomalies of the rapid crustal transition deepened westward, gravity gradient, high Vp/Vs ratio of average 2.2, and geological features of thrust faulting style with strike slip history. Response spectra for rock and soil sites are, respectively, estimated and compared for different tectonic regimes, based on the study of source, path and site effects, emphasizing soil site amplification effect. Also studied are safety concerned issues for prevention of future damaging earthquakes including geological hazards, seismic design, earthquake early warning systems (EEWS), and strategies of long term to short term earthquake forecasting. A sample of design spectra is presented on weighted average rock-site attenuation models. Topic on seismotectonics and earthquake dynamics in the areas of high seismic risk could be well incorporated with engineering geology and environmental engineering. Study on performances of the newly designed and constructed engineering structures should provide most valuable input to improving seismic design codes in China and throughout the world. It is a challenging task to predict earthquakes; however, effort should never be given up. Earthquake disaster reduction and prevention is a realistic measure for safeguard of future damaging earthquakes.
The May 12, Ms 8.0 Wenchuan earthquake is tectonically due to the convergence of the India plate against the Eurasia plate at a rate of ~50 mm/yr, which resulted in the crustal movement toward the eastern Sichuan Basin and the southeastern China continent from the uplifted Tibetan Plateau. The epicentral area is located in the active Longmenshan centralized seismic zone along which the aftershocks are concentrated within a ~350 km long and ~100 km wide active belt of horizontal projection. Hypocentral depths range generally from ~10 to ~20 km within the crustal seismogenic zone above the brittle-ductile transition boundary, characterized typically by shallow tectonic earthquakes. Focal mechanism of the Wenchuan earthquake bears a close correlation with the Longmenshan tectonic movement indicated by the particular deep structural anomalies of the rapid crustal transition deepened westward, gravity gradient, high Vp/Vs ratio of average 2.2, and geological features of thrust faulting style with strike slip history. Response spectra for rock and soil sites are, respectively, estimated and compared for different tectonic regimes, based on the study of source, path and site effects, emphasizing soil site amplification effect. Also studied are safety concerned issues for prevention of future damaging earthquakes including geological hazards, seismic design, earthquake early warning systems (EEWS), and strategies of long term to short term earthquake forecasting. A sample of design spectra is presented on weighted average rock-site attenuation models. Topic on seismotectonics and earthquake dynamics in the areas of high seismic risk could be well incorporated with engineering geology and environmental engineering. Study on performances of the newly designed and constructed engineering structures should provide most valuable input to improving seismic design codes in China and throughout the world. It is a challenging task to predict earthquakes; however, effort should never be given up. Earthquake disaster reduction and prevention is a realistic measure for safeguard of future damaging earthquakes.
引文
Abrahamson N A and Silva W J.1997,Empirical response spectra attenuation relations for shallow crustal earthquakes[J].Seism.Res.Lett.,68(1):94-127.
Atkinson G M and Chen S Z.1997.Regional seismograms from historical earthquakes in southeastern Canada[J].Seism.Res.Lett.,68:797-807.
Boore D M,Joyner W B and Fumal T E.1997.Equations for estimating horizontal response spectra and peak acceleration from western North American earthquakes:A summary of recent work[J].Seism.Res.Lett.,68(1):128-153.
Burchfiel B C,Chen Z,Liu Yet al.1995.Tectonics of the Longmen Shan and adjacent regions,central China[G]//Ernst W G,Skinner B J and Taylored L A,Eds.Intl.Geol.Rev.,37,8
Campbell K W and Bozorgnia Y.2003.Updated near-source ground-motion(attenuation)relations for the horizontal and vertical components of peak ground acceleration and acceleration response spectra[J].Bull.Seism.Soc.Am.,93(1):314-331.
Chen S Z.1983.Deep structural features of southeastern China and its adjoining seas[J].Journal of Nanjing University(Natural Sciences),19:521-536.
Chen S Z.1986.Geophysical analysis on seismicity and spatial distribution of oil-and gas-bearing basins in southeastern China and adjacent seas[J].Geotectonica et Metallogenia,10:247-261.
Chen S Z and Hedley D G F.1990.Waveform analysis and velocity structure at Quirke Mine and adjacent areas in Ontario,Part1:Source parameters for evidence of the failure zone[M].MRL90-117(TR),1-34,CANMET,Energy,Mines and Resources Canada.(Also in:Natural Resources&Earth Sciences(NTIS),Vol.91,No.25/1990;www.collectionscanada.ca/wbin/resanet)
Chen S Z.1990.Waveform analysis and velocity structure at Quirke Mine and adjacent areas in Ontario,Part2:Extension of the failure zone[M].MRL90-130(TR),1-21,CANMET,Energy,Mines and Resources Canada.
Chen S Z.1992.Isostatic geoid anomalies and lithospheric structure of the Xizang-Qinghai plateau-North Indian Ocean region[J].Geotectonica et Metallogenia,16:367-378.
Chen S Z.1993.Gravity,lithospheric structure and plate dynamic evolution of the Himalayas and surrounding areas[J].Geotectonica et Metallogenia,17:315-334.
Chen S Z.1994.Penetration of Indian plate under Tibetan plateau,EOS Trans[J].AGU,75(44):734-735.
Chen S Z.1995a.Deep structures in China and adjacent areas:Plate tectonics and its metallogenic significance[J].Acta Geologica Sinica,8:223-239.(in Chinese with English abstract)
Chen S Z,Reed L D,Rubin G A,et al.1995b.Physical propertiesof rocks loaded by sonic stress wave[G]Geophysics and theEnvironment,IUGG XXI General Assembly,p.A427.
Chen S Z.1995c.Microseismic characteristics of a failure zone in Ontario,s Elliot Lake Mines,Canada[M]//Chen Y,Lu B and Hao Z.Eds.China Postdoctor,s Contributions to the30th International Geological Congress,China Petroleum Industry Press,Beijing,107-120.(in Chinese)
Chen S Z.1998a.Dynamic friction:I.Experimental observations of rock friction[J].Geotectonica et Metallogenia,22:28-41.
Chen SZ.1998b.Dynamic friction:II.Depth distribution of earthquakes in continental crust[J].Geotectonica et Metallogenia,22:105-127.
Chen S Z and Atkinson G M.2001a.Similarity of regional earthquake source spectra[J].EOS,82(47):F903.
Chen S Z and Atkinson G M.2001b.Source radiation and responses of wave propagation[J].Geotectonica et Metallogenia,25(1-2):168-178.
Chen S Z and Atkinson G M.2002.Global Comparisons of earthquake source spectra[J].Bull.Seism.Soc.Am.,92(3):885-895.
Chen S Z.2002.Earthquake source scaling[J].Seism.Res.Lett.,73(2):236.
Chen S Z.2003,Empirical prediction of earthquake source radiation[J].Seism.Res.Lett.,74(2):223.
Chen S Z.2004a.Structure and dynamics of lithosphere across the Tibetan Plateau,Indian Subcontinent,and North Indian Ocean[M]//Earth,s Deep Structures and Dynamics of Continents in China.Beijing:Science Press,277-294.
Chen S Z.2004b.Understanding earthquake source radiation[J].Geol.Jour.of China Uni.,10(4):606-614.
Chen S Z.2004c.Earthquake source radiation:Isolating source spectra from propagation transfer functions,in Advances of Seismology and Physics of the Earth’s Interior[M]//Honor of Academician Zeng Rongsheng,s80th Birthday,Beijing:Seismological Press,644-663.(in Chinese)
Chen S Z.2004d.Horizontal-to-vertical spectral ratio and site responses[J].Seism.Res.Lett.,75(2):248.
Chen S Z.2005.Earthquake dynamics and plate tectonics:Seismic hazard assessment[J].Geol.J.China Universities,11(4):
Chen S Z.2007.Earthquake dynamics:Source distribution with respect to lithospheric rheology[J].Geotectonica et Metallogenia,31:265-272.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau[J].Tectonics,26:TC4005.
Dreger D.2008.The large aftershocks of the Northridge earthquake andtheir relationship to mainshock slip and fault zone complexity,http:/seismo.berkeley.edu/~dreger/paper.html.
Emolo A and Zollo A.2005.Kinematic source parameters for the1989Loma Prieta earthquake from the nonlinear inversion of accelerograms[J].Bull.Seism.Soc.Am.,95:981-994.
Idriss I M.1995.An overview of earthquake ground motions pertinent to seismic zonation[C].Proceedings Volume III of the Fifth International Conference on Seismic Zonation,October17-19,Nice French Riviera.
Meade B J.Present-day kinematics at the India-Asia collision zone[J].Geology,35:81-84.
Sadigh K,Chang C Y,Egan J A,ET AL.1997.Attenuation relationships for shallow crustal earthquakes based on California strong motion data[J].Seism.Res.Lett.,68(1):180-189.
Spudich P,Joyner W B,Lindh A G,et al.1999.SEA99—A revised ground motion prediction relation for use in extensional tectonic regimes[J].Bull.Seism.Soc.Am.,89(5):1156-1170.
Wald D J and Heaton T H.1994.Spatial and temporal distribution of slip for the1992Landers,California earthquake[J].Bull.Seis.Soc.Am.,84:668-691.
Atkinson G M and Chen S Z.1997.Regional seismograms from historical earthquakes in southeastern Canada[J].Seism.Res.Lett.,68:797-807.
Boore D M,Joyner W B and Fumal T E.1997.Equations for estimating horizontal response spectra and peak acceleration from western North American earthquakes:A summary of recent work[J].Seism.Res.Lett.,68(1):128-153.
Burchfiel B C,Chen Z,Liu Yet al.1995.Tectonics of the Longmen Shan and adjacent regions,central China[G]//Ernst W G,Skinner B J and Taylored L A,Eds.Intl.Geol.Rev.,37,8
Campbell K W and Bozorgnia Y.2003.Updated near-source ground-motion(attenuation)relations for the horizontal and vertical components of peak ground acceleration and acceleration response spectra[J].Bull.Seism.Soc.Am.,93(1):314-331.
Chen S Z.1983.Deep structural features of southeastern China and its adjoining seas[J].Journal of Nanjing University(Natural Sciences),19:521-536.
Chen S Z.1986.Geophysical analysis on seismicity and spatial distribution of oil-and gas-bearing basins in southeastern China and adjacent seas[J].Geotectonica et Metallogenia,10:247-261.
Chen S Z and Hedley D G F.1990.Waveform analysis and velocity structure at Quirke Mine and adjacent areas in Ontario,Part1:Source parameters for evidence of the failure zone[M].MRL90-117(TR),1-34,CANMET,Energy,Mines and Resources Canada.(Also in:Natural Resources&Earth Sciences(NTIS),Vol.91,No.25/1990;www.collectionscanada.ca/wbin/resanet)
Chen S Z.1990.Waveform analysis and velocity structure at Quirke Mine and adjacent areas in Ontario,Part2:Extension of the failure zone[M].MRL90-130(TR),1-21,CANMET,Energy,Mines and Resources Canada.
Chen S Z.1992.Isostatic geoid anomalies and lithospheric structure of the Xizang-Qinghai plateau-North Indian Ocean region[J].Geotectonica et Metallogenia,16:367-378.
Chen S Z.1993.Gravity,lithospheric structure and plate dynamic evolution of the Himalayas and surrounding areas[J].Geotectonica et Metallogenia,17:315-334.
Chen S Z.1994.Penetration of Indian plate under Tibetan plateau,EOS Trans[J].AGU,75(44):734-735.
Chen S Z.1995a.Deep structures in China and adjacent areas:Plate tectonics and its metallogenic significance[J].Acta Geologica Sinica,8:223-239.(in Chinese with English abstract)
Chen S Z,Reed L D,Rubin G A,et al.1995b.Physical propertiesof rocks loaded by sonic stress wave[G]Geophysics and theEnvironment,IUGG XXI General Assembly,p.A427.
Chen S Z.1995c.Microseismic characteristics of a failure zone in Ontario,s Elliot Lake Mines,Canada[M]//Chen Y,Lu B and Hao Z.Eds.China Postdoctor,s Contributions to the30th International Geological Congress,China Petroleum Industry Press,Beijing,107-120.(in Chinese)
Chen S Z.1998a.Dynamic friction:I.Experimental observations of rock friction[J].Geotectonica et Metallogenia,22:28-41.
Chen SZ.1998b.Dynamic friction:II.Depth distribution of earthquakes in continental crust[J].Geotectonica et Metallogenia,22:105-127.
Chen S Z and Atkinson G M.2001a.Similarity of regional earthquake source spectra[J].EOS,82(47):F903.
Chen S Z and Atkinson G M.2001b.Source radiation and responses of wave propagation[J].Geotectonica et Metallogenia,25(1-2):168-178.
Chen S Z and Atkinson G M.2002.Global Comparisons of earthquake source spectra[J].Bull.Seism.Soc.Am.,92(3):885-895.
Chen S Z.2002.Earthquake source scaling[J].Seism.Res.Lett.,73(2):236.
Chen S Z.2003,Empirical prediction of earthquake source radiation[J].Seism.Res.Lett.,74(2):223.
Chen S Z.2004a.Structure and dynamics of lithosphere across the Tibetan Plateau,Indian Subcontinent,and North Indian Ocean[M]//Earth,s Deep Structures and Dynamics of Continents in China.Beijing:Science Press,277-294.
Chen S Z.2004b.Understanding earthquake source radiation[J].Geol.Jour.of China Uni.,10(4):606-614.
Chen S Z.2004c.Earthquake source radiation:Isolating source spectra from propagation transfer functions,in Advances of Seismology and Physics of the Earth’s Interior[M]//Honor of Academician Zeng Rongsheng,s80th Birthday,Beijing:Seismological Press,644-663.(in Chinese)
Chen S Z.2004d.Horizontal-to-vertical spectral ratio and site responses[J].Seism.Res.Lett.,75(2):248.
Chen S Z.2005.Earthquake dynamics and plate tectonics:Seismic hazard assessment[J].Geol.J.China Universities,11(4):
Chen S Z.2007.Earthquake dynamics:Source distribution with respect to lithospheric rheology[J].Geotectonica et Metallogenia,31:265-272.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau[J].Tectonics,26:TC4005.
Dreger D.2008.The large aftershocks of the Northridge earthquake andtheir relationship to mainshock slip and fault zone complexity,http:/seismo.berkeley.edu/~dreger/paper.html.
Emolo A and Zollo A.2005.Kinematic source parameters for the1989Loma Prieta earthquake from the nonlinear inversion of accelerograms[J].Bull.Seism.Soc.Am.,95:981-994.
Idriss I M.1995.An overview of earthquake ground motions pertinent to seismic zonation[C].Proceedings Volume III of the Fifth International Conference on Seismic Zonation,October17-19,Nice French Riviera.
Meade B J.Present-day kinematics at the India-Asia collision zone[J].Geology,35:81-84.
Sadigh K,Chang C Y,Egan J A,ET AL.1997.Attenuation relationships for shallow crustal earthquakes based on California strong motion data[J].Seism.Res.Lett.,68(1):180-189.
Spudich P,Joyner W B,Lindh A G,et al.1999.SEA99—A revised ground motion prediction relation for use in extensional tectonic regimes[J].Bull.Seism.Soc.Am.,89(5):1156-1170.
Wald D J and Heaton T H.1994.Spatial and temporal distribution of slip for the1992Landers,California earthquake[J].Bull.Seis.Soc.Am.,84:668-691.
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