应用统计物理方法分析川滇地区地震危险性
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摘要
川滇菱形块体及其边界断裂带(21°～33°N,96°～108°E)是中国大陆地震活动最强烈的地区之一,该地区发生的一系列大地震造成了巨大的人员伤亡和财产损失。文中分别应用基于地震空间相关性和地壳形变场的预测方法分析了该地区未来的地震危险性。由Kagan等(1994)提出的基于地震空间相关性的方法,假定未来发生地震的概率与历史发生地震的频度成正比,根据历史地震目录建立统计学模型估计未来发生地震的概率。回溯性检验表明,这种方法对于评估地震复发周期较短的断裂带的地震危险性有较高的有效性,但对于地震复发周期较长的断裂带,如龙门山断裂带,很难给出一个理想的预期。由Shen等(2007)提出的基于地壳形变场的方法,假定长期地震危险性与地壳构造应变率成正比,根据由GPS观测获得的应变率场建立统计学模型评估未来的地震危险性。回溯性检验表明,川滇地区过去30a间发生的地震与区域应变率的大小没有明显的对应关系,但过去500a间发生的地震与应变率场有很高的相关性,表明由10a时间尺度的大地测量资料得到的地壳应变场可以很好地反映数百a时间尺度的地震危险性。
As the southeastern margin of the Tibetan plateau,the Sichuan-Yunnan region is carved by ample tectonic active faults. Many strong earthquakes have taken place in the past,and some of which resulted in massive damages and great losses of human lives. In this study we attempt to estimate the seismic hazard potential using two different approaches. Our first approach follows Kagan and Jackson(1994)and uses earthquake catalog data to estimate the mid-to long-term spatial probability of strong earthquakes,based on the assumption that earthquake likelihood is proportional to the intensity and quantity of past events. A retrospective test shows that the model offers reasonable ‘forecasts'statistically over the last 37 years,based on the catalog data of previous 470 years for model constraints. Our second approach is to use secular geodetic strain rate deduced from GPS velocity data to constrain earthquake probability model,assuming that likelihood of strong earthquakes is spatially proportional to the geodetic strain rate. A retrospective test of the model with earthquake occurrence of the past 30 years shows that the model ‘forecasted’poorly,but did reasonably well when comparing with the catalog data of the past 500 years,suggesting that the geodetic strain rate obtained at the decade scale may still be a good indicator of long-term earthquake activity in the region,but only at a time scale of hundreds of years.
As the southeastern margin of the Tibetan plateau,the Sichuan-Yunnan region is carved by ample tectonic active faults. Many strong earthquakes have taken place in the past,and some of which resulted in massive damages and great losses of human lives. In this study we attempt to estimate the seismic hazard potential using two different approaches. Our first approach follows Kagan and Jackson(1994)and uses earthquake catalog data to estimate the mid-to long-term spatial probability of strong earthquakes,based on the assumption that earthquake likelihood is proportional to the intensity and quantity of past events. A retrospective test shows that the model offers reasonable ‘forecasts'statistically over the last 37 years,based on the catalog data of previous 470 years for model constraints. Our second approach is to use secular geodetic strain rate deduced from GPS velocity data to constrain earthquake probability model,assuming that likelihood of strong earthquakes is spatially proportional to the geodetic strain rate. A retrospective test of the model with earthquake occurrence of the past 30 years shows that the model ‘forecasted’poorly,but did reasonably well when comparing with the catalog data of the past 500 years,suggesting that the geodetic strain rate obtained at the decade scale may still be a good indicator of long-term earthquake activity in the region,but only at a time scale of hundreds of years.
引文
蒋长胜,吴忠良.2008.对地震预测的一个统计物理算法在川滇地区的回溯性预测检验[J].中国科学(D辑),38(7):852—861.JIANG Chang-sheng,WU Zhong-liang.2008.Retrospective forecasting test of a statistical physics model for earthquakesin Sichuan-Yunnan region[J].Science in China(Ser D),51(10):1401—1410.
蒋长胜,庄建仓.2010.基于时-空ETAS模型给出的川滇地区背景地震活动和强震潜在危险区[J].地球物理学报,53(2):305—317.JIANG Chang-sheng,ZHUANG Jian-cang.2010.Evaluation of background seismicity and potential source zones ofstrong earthquakes in the Sichuan-Yunnan region based on the space-time ETAS model[J].Chinese J Geophys,53(2):305—317(in Chinese).
王敏,沈正康,牛之俊,等.2003.现今中国大陆地壳运动与活动块体模型[J].中国科学(D辑),33(增刊):21—32.WANG Min,SHEN Zheng-kang,NIU Zhi-jun,et al.2003.Contemporary crustal deformation of the Chinese Continentand tectonic block model[J].Science in China(Ser D),46(Suppl):25—40.
闻学泽.2001.活动断裂的可变破裂尺度地震行为与级联破裂模式的应用[J].地震学报,23(4):380—390.WEN Xue-ze.2001.Earthquake behavior of variable rupture-scale on active faults and application of the cascade-ruptu-ring model[J].Acta Seismologica Sinica,23(4):38—390(in Chinese).
徐锡伟,张培震,闻学泽,等.2005.川西及其邻近地区活动构造基本特征与强震复发模型[J].地震地质,27(3):446—461.XU Xi-wei,ZHANG Pei-zhen,WEN Xue-ze,et al.2005.Features of active tectonics and recurrence behaviors of strongearthquakes in the western Sichuan Province and its adjacent regions[J].Seismology and Geology,27(3):446—461(in Chinese).
易桂喜,徐锡伟.2002.川滇地区若干活动断裂带整体的强地震复发特征研究[J].中国地震,18(3):267—276.YI Gui-xi,XU Xi-wei.2002.Study on recurrence behaviors of strong earthquakes for several entireties of active faultzones in Sichuan-Yunnan region[J].Earthquake Research in China,18(3):267—276(in Chinese).
易桂喜,闻学泽,范军,等.2004.由地震活动参数分析安宁河-则木河断裂带的现今活动习性及地震危险性[J].地震学报,26(3):294—303.YI Gui-xi,WEN Xue-ze,FAN Jun,et al.2004.Assessing current faulting behaviors and seismic risk of the Anninghe-Zemuhe Fault zone from seismicity parameters[J].Acta Seismologica Sinica,17(3):322—333.
易桂喜,闻学泽,王思维,等.2006.由地震活动参数分析龙门山-岷山断裂带的现今活动习性与强震危险性[J].中国地震,22(2):117—125.YI Gui-xi,WEN Xue-ze,WANG Si-wei,et al.2006.Study on fault sliding behaviors and strong-earthquake risk of theLongmenshan-Minshan Fault zones from current seismicity parameters[J].Earthquake Research in China,22(2):117—125(in Chinese).
易桂喜,闻学泽,苏有锦.2008.川滇活动地块东边界强震危险性研究[J].地球物理学报,51(6):1719—1725.YI Gui-xi,WEN Xue-ze,SU You-jin.2008.Study on the potential strong-earthquake risk for the eastern boundary of theSichuan-Yunnan active faulted-block,China[J].Chinese J Geophys,51(6):1151—1158.
Bird P,Kagan Y Y.2004.Plate-tectonic analysis of shallow seismicity:Apparent boundary width,beta,corner magni-tude,coupled lithosphere thickness,and coupling in seven tectonic settings[J].Bulletin of the Seismological Soci-ety of America,94(6):2380—2399.
Burchfiel B C,Royden L H,Van der Hilst R D,et al.2008.A geological and geophysical context for the Wenchuanearthquake of12May2008,Sichuan,People's Republic of China[J].GSA Today,18(7):4—11.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan Faults at the eastern marginof the Tibetan plateau[J].Tectonics,26(4):1—17.
Huang Q,Sobolev G A,Nagao T.2001.Characteristics of the seismic quiescence and activation patterns before the M=7.2Kobe earthquake,January17,1995[J].Tectonophysics,337(1-2):99—116.
Jackson D D,Shen Z K,Potter D,et al.1997.Southern California deformation[J].Science,277(5332):1621.
Jackson D D,Kagan Y Y.1999.Testable earthquake forecasts for1999[J].Seismological Research Letters,70(4):393—403.
Kagan Y,Knopoff L.1977.Earthquake risk prediction as a stochastic process[J].Physics of the Earth and PlanetaryInteriors,14(2):97—108.
Kagan Y Y,Jackson D D.1994.Long-term probabilistic forecasting of earthquakes[J].Journal of Geophysical Re-search,99(13):685—700.
Kagan Y Y,Jackson D D.2000.Probabilistic forecasting of earthquakes[J].Geophysical Journal International,143(2):438—453.
Kagan Y Y.2009.Testing long-term earthquake forecasts:Likelihood methods and error diagrams[J].GeophysicalJournal International,177(2):532—542.
Kagan Y Y,Jackson D D.2011.Global earthquake forecasts[J].Geophysical Journal International,184(2):759—776.
Keilis-Borok V I,Rotwain I M.1990.Diagnosis of time of increased probability of strong earthquakes in different regionsof the world:Algorithm CN[J].Physics of the Earth and Planetary Interiors,61(1-2):57—72.
Rong Y F,Jackson D D.2002.Earthquake potential in and around China-Estimated from past earthquakes[J].Geo-physical Research Letters,29(16):21—27.
Rundle J B,Klein W,Turcotte D L,et al.2000.Precursory seismic activation and critical-point phenomena[J].Pureand Applied Geophysics,157(11/12):2165—2182.
Rundle J B,Turcotte D L,Shcherbakov R,et al.2003.Statistical physics approach to understanding the multi-scale dy-namics of earthquake fault systems[J].Rev Geophys,41(4):1019.
Shen Z K,Jackson D D,Bob X G.1996.Crustal deformation across and beyond the Los Angeles Basin from geodeticmeasurements[J].Journal of Geophysical Research,101(B12):27927—27957,980.
Shen Z K,Jackson D D,Kagan Y Y.2007.Implications of geodetic strain rate for future earthquakes,with a five-yearforecast of M5earthquakes in southern California[J].Seismological Research Letters,78(1):116—120.
Shen Z K,Sun J,Zhang P,et al.2009.Slip maxima at fault junctions and rupturing of barriers during the2008Wen-chuan earthquake[J].Nature Geoscience,2(10):718—724.
Shen Z K,King R W,Agnew D C,et al.2011.A unified analysis of crustal motion in Southern California,1970-2004:The SCEC crustal motion map[J].J Geophys Res,116:B11402.doi:10.1029/2011JB008549.
Tiampo K F,Rundle J B,McGinnis S,et al.2002.Mean-field threshold systems and phase dynamics:An application toearthquake fault system[J].Europhys Letter,60:481—487.
Zhang P Z,Wen X,Shen Z K,et al.2010.Oblique,high-angle,listric-reverse faulting and associated development ofstrain:The Wenchuan earthquake of May12,2008,Sichuan,China[J].Annual Review of Earth and PlanetarySciences,38:353—382.
蒋长胜,庄建仓.2010.基于时-空ETAS模型给出的川滇地区背景地震活动和强震潜在危险区[J].地球物理学报,53(2):305—317.JIANG Chang-sheng,ZHUANG Jian-cang.2010.Evaluation of background seismicity and potential source zones ofstrong earthquakes in the Sichuan-Yunnan region based on the space-time ETAS model[J].Chinese J Geophys,53(2):305—317(in Chinese).
王敏,沈正康,牛之俊,等.2003.现今中国大陆地壳运动与活动块体模型[J].中国科学(D辑),33(增刊):21—32.WANG Min,SHEN Zheng-kang,NIU Zhi-jun,et al.2003.Contemporary crustal deformation of the Chinese Continentand tectonic block model[J].Science in China(Ser D),46(Suppl):25—40.
闻学泽.2001.活动断裂的可变破裂尺度地震行为与级联破裂模式的应用[J].地震学报,23(4):380—390.WEN Xue-ze.2001.Earthquake behavior of variable rupture-scale on active faults and application of the cascade-ruptu-ring model[J].Acta Seismologica Sinica,23(4):38—390(in Chinese).
徐锡伟,张培震,闻学泽,等.2005.川西及其邻近地区活动构造基本特征与强震复发模型[J].地震地质,27(3):446—461.XU Xi-wei,ZHANG Pei-zhen,WEN Xue-ze,et al.2005.Features of active tectonics and recurrence behaviors of strongearthquakes in the western Sichuan Province and its adjacent regions[J].Seismology and Geology,27(3):446—461(in Chinese).
易桂喜,徐锡伟.2002.川滇地区若干活动断裂带整体的强地震复发特征研究[J].中国地震,18(3):267—276.YI Gui-xi,XU Xi-wei.2002.Study on recurrence behaviors of strong earthquakes for several entireties of active faultzones in Sichuan-Yunnan region[J].Earthquake Research in China,18(3):267—276(in Chinese).
易桂喜,闻学泽,范军,等.2004.由地震活动参数分析安宁河-则木河断裂带的现今活动习性及地震危险性[J].地震学报,26(3):294—303.YI Gui-xi,WEN Xue-ze,FAN Jun,et al.2004.Assessing current faulting behaviors and seismic risk of the Anninghe-Zemuhe Fault zone from seismicity parameters[J].Acta Seismologica Sinica,17(3):322—333.
易桂喜,闻学泽,王思维,等.2006.由地震活动参数分析龙门山-岷山断裂带的现今活动习性与强震危险性[J].中国地震,22(2):117—125.YI Gui-xi,WEN Xue-ze,WANG Si-wei,et al.2006.Study on fault sliding behaviors and strong-earthquake risk of theLongmenshan-Minshan Fault zones from current seismicity parameters[J].Earthquake Research in China,22(2):117—125(in Chinese).
易桂喜,闻学泽,苏有锦.2008.川滇活动地块东边界强震危险性研究[J].地球物理学报,51(6):1719—1725.YI Gui-xi,WEN Xue-ze,SU You-jin.2008.Study on the potential strong-earthquake risk for the eastern boundary of theSichuan-Yunnan active faulted-block,China[J].Chinese J Geophys,51(6):1151—1158.
Bird P,Kagan Y Y.2004.Plate-tectonic analysis of shallow seismicity:Apparent boundary width,beta,corner magni-tude,coupled lithosphere thickness,and coupling in seven tectonic settings[J].Bulletin of the Seismological Soci-ety of America,94(6):2380—2399.
Burchfiel B C,Royden L H,Van der Hilst R D,et al.2008.A geological and geophysical context for the Wenchuanearthquake of12May2008,Sichuan,People's Republic of China[J].GSA Today,18(7):4—11.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan Faults at the eastern marginof the Tibetan plateau[J].Tectonics,26(4):1—17.
Huang Q,Sobolev G A,Nagao T.2001.Characteristics of the seismic quiescence and activation patterns before the M=7.2Kobe earthquake,January17,1995[J].Tectonophysics,337(1-2):99—116.
Jackson D D,Shen Z K,Potter D,et al.1997.Southern California deformation[J].Science,277(5332):1621.
Jackson D D,Kagan Y Y.1999.Testable earthquake forecasts for1999[J].Seismological Research Letters,70(4):393—403.
Kagan Y,Knopoff L.1977.Earthquake risk prediction as a stochastic process[J].Physics of the Earth and PlanetaryInteriors,14(2):97—108.
Kagan Y Y,Jackson D D.1994.Long-term probabilistic forecasting of earthquakes[J].Journal of Geophysical Re-search,99(13):685—700.
Kagan Y Y,Jackson D D.2000.Probabilistic forecasting of earthquakes[J].Geophysical Journal International,143(2):438—453.
Kagan Y Y.2009.Testing long-term earthquake forecasts:Likelihood methods and error diagrams[J].GeophysicalJournal International,177(2):532—542.
Kagan Y Y,Jackson D D.2011.Global earthquake forecasts[J].Geophysical Journal International,184(2):759—776.
Keilis-Borok V I,Rotwain I M.1990.Diagnosis of time of increased probability of strong earthquakes in different regionsof the world:Algorithm CN[J].Physics of the Earth and Planetary Interiors,61(1-2):57—72.
Rong Y F,Jackson D D.2002.Earthquake potential in and around China-Estimated from past earthquakes[J].Geo-physical Research Letters,29(16):21—27.
Rundle J B,Klein W,Turcotte D L,et al.2000.Precursory seismic activation and critical-point phenomena[J].Pureand Applied Geophysics,157(11/12):2165—2182.
Rundle J B,Turcotte D L,Shcherbakov R,et al.2003.Statistical physics approach to understanding the multi-scale dy-namics of earthquake fault systems[J].Rev Geophys,41(4):1019.
Shen Z K,Jackson D D,Bob X G.1996.Crustal deformation across and beyond the Los Angeles Basin from geodeticmeasurements[J].Journal of Geophysical Research,101(B12):27927—27957,980.
Shen Z K,Jackson D D,Kagan Y Y.2007.Implications of geodetic strain rate for future earthquakes,with a five-yearforecast of M5earthquakes in southern California[J].Seismological Research Letters,78(1):116—120.
Shen Z K,Sun J,Zhang P,et al.2009.Slip maxima at fault junctions and rupturing of barriers during the2008Wen-chuan earthquake[J].Nature Geoscience,2(10):718—724.
Shen Z K,King R W,Agnew D C,et al.2011.A unified analysis of crustal motion in Southern California,1970-2004:The SCEC crustal motion map[J].J Geophys Res,116:B11402.doi:10.1029/2011JB008549.
Tiampo K F,Rundle J B,McGinnis S,et al.2002.Mean-field threshold systems and phase dynamics:An application toearthquake fault system[J].Europhys Letter,60:481—487.
Zhang P Z,Wen X,Shen Z K,et al.2010.Oblique,high-angle,listric-reverse faulting and associated development ofstrain:The Wenchuan earthquake of May12,2008,Sichuan,China[J].Annual Review of Earth and PlanetarySciences,38:353—382.
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