汶川大地震触发地质灾害的断层效应分析
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摘要
"5·12"汶川大地震(Ms=8.0)触发了数以万计的崩滑地质灾害,分布范围约10万km2。这些地质灾害的空间分布固然受地形地貌、地层岩性和人类工程活动等因素的影响,然而主要还是受到发震断层的控制,沿发震断裂呈带状分布。通过都(江堰)—汶(川)路、北川—安县、马公—红光3个地质灾害集中发育区的研究,发现汶川地震地质灾害具有以下断层效应:(1)由于属逆断型发震,地质灾害的分布表现出了明显的"上/下盘效应",发震断层上盘较下盘地质灾害分布密度高、范围广、规模大;(2)断层上盘0～7km范围为地质灾害强发育区,断层上盘7～11km范围和下盘0～5km范围为地质灾害中等发育区;绝大多数的大型滑坡都分布在距断层5km范围内;(3)断裂的转折和错列部位是地质灾害集中发育部位,大型地质灾害也往往发生在这些部位;(4)滑坡滑动的优势方向为NW-SE,与映秀—北川断裂的空间展布方向基本垂直,这与地震波垂直于断层方向传播有密切的关系;(5)地震地质灾害主要集中发育在Ⅸ度及其以上烈度的区域。其中,Ⅺ度区发育密度与Ⅹ度区的基本相当,Ⅸ度区灾害密度只有前两者的1/3,而Ⅷ度区发育密度只有Ⅺ度区或Ⅹ度区的1/10。
A great number of collapse and slide geo-hazards had been triggered by "5·12" Wenchuan Earthquake,covering 0.1M km2 or so.Undoubtedly,their distribution was influenced by topography and morphology,stratigraphy,people's engineering operations,and so on.But their distribution mainly was controlled by the faults triggering seism,and they distributed along those faults like a ribbon.Based on the study in three geo-hazards concentration regions,namely,from Dujiangyan to Wenchuan,from Beichuan to Anxian and from Magong to Hongguang,the following fault effects of geo-hazards in Wenchuan Earthquake were found:(1)Because the triggering-earthquake faults were reverse fault,the distribution of geo-hazards showed clear "Upper plate/lower plate effect".In detail,compared with lower plate,the upper plate had higher distribution density,wider scope and larger scale;(2)Intensely developed region of geo-hazard ranged from 0 to 7 km in upper plate.Moderately developed region ranged from 7 to 11km in upper plate,and from 0 to 5km in lower plate;Vast majority of lager-scale landslides were about 5km away from faults;(3)The transition and stagger parts of fractures are usually the concentration zone of geo-hazards,and large-scale geo-hazards also frequently happened here;(4)The advantage orientation of sliding was NW-SE,which was nearly orthogonal to the extension direction of the fault of Yingxiu-beichuan.This was closed correlation to the fact that the propagation of earthquake wave was perpendicular to the strike of fault;(5)Earthquake geo-hazards mainly developed in these regions where earthquake intensity was equal to or above IX.The density of development was nearly the same in XI intensity zone and X intensity zone.The geo-hazard density in IX intensity zone was only one-third of the two former zones.Whereas,the development density in VIII intensity zone was only one-tenth of XI intensity zone or X intensity zone.
A great number of collapse and slide geo-hazards had been triggered by "5·12" Wenchuan Earthquake,covering 0.1M km2 or so.Undoubtedly,their distribution was influenced by topography and morphology,stratigraphy,people's engineering operations,and so on.But their distribution mainly was controlled by the faults triggering seism,and they distributed along those faults like a ribbon.Based on the study in three geo-hazards concentration regions,namely,from Dujiangyan to Wenchuan,from Beichuan to Anxian and from Magong to Hongguang,the following fault effects of geo-hazards in Wenchuan Earthquake were found:(1)Because the triggering-earthquake faults were reverse fault,the distribution of geo-hazards showed clear "Upper plate/lower plate effect".In detail,compared with lower plate,the upper plate had higher distribution density,wider scope and larger scale;(2)Intensely developed region of geo-hazard ranged from 0 to 7 km in upper plate.Moderately developed region ranged from 7 to 11km in upper plate,and from 0 to 5km in lower plate;Vast majority of lager-scale landslides were about 5km away from faults;(3)The transition and stagger parts of fractures are usually the concentration zone of geo-hazards,and large-scale geo-hazards also frequently happened here;(4)The advantage orientation of sliding was NW-SE,which was nearly orthogonal to the extension direction of the fault of Yingxiu-beichuan.This was closed correlation to the fact that the propagation of earthquake wave was perpendicular to the strike of fault;(5)Earthquake geo-hazards mainly developed in these regions where earthquake intensity was equal to or above IX.The density of development was nearly the same in XI intensity zone and X intensity zone.The geo-hazard density in IX intensity zone was only one-third of the two former zones.Whereas,the development density in VIII intensity zone was only one-tenth of XI intensity zone or X intensity zone.
引文
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[7]李忠生.国内外地震滑坡灾害研究综述[J].灾害学,2003,18(4):64～70.Li Zhongsheng.The State of the art of the research on seismic landslide hazard at home and abroad.Journal of Catastrophology,2003,18(4):64～70.
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[9]胡广韬.滑坡动力学[M].北京:地质出版社,1995.Hu Guangtao.Landslide dynamics.Beijing:Geological PublishingHouse,1995.
[10]毛彦龙,胡广韬,赵法锁,等.地震动触发滑坡体滑动的机理[J].西安工程学院学报,1998,20(4):45～48.Mao Yanlong,Hu Guangtao,Zhao Fasuo,et al..Mechanics of the landslide sliding caused by seismic.Journal of Xi′an Engi-neering University,1998,20(4):45～48.
[11]鲍叶静,高孟潭,姜慧.地震诱发滑坡的概率分析[J].岩石力学与工程学报,2005,24(1):66～70.Bao Yejing,Gao Mengtan,Jiang hui.Probabilistic analysis of earthquake-induced landslides.Chinese Journal of Rock Me-chanics and Engineering,2005,24(1):66～70.
[12]Keefer D V.Statistical analysis of an earthquake-induced land-slide distribution the1989Loma Prieta,California event[J].Engineering Geology,2000,58,231～249.
[13]Jibson R W,Harp E L,and Michael J A.Amethod for producing digital probabilistic seismic landslide hazard maps[J].Engineer-ing Geology,Special Issue,2000,(58):3～4.
[14]Mohammad R.Mahdavifar,Shahryar Solaymani,Mohammad K.Jafari.Landslides triggered by the Avaj,Iran earthquake of June22,2002[J].Engineering Geology,2006,86,166～182.
[15]Wang W N,Nakamura H,Tsuchiya S,Chen C C.Distributions of landslides triggered by the Chi-Chi earthquake in Central Tai-wan on September21,1999[J].Journal of the Japan Landslide Society,2002,38(4):318～326.
[16]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433～444.Yin Yaoping.Researches on the geo-hazards triggered by Wen-chuan Earthquake,Sichuan.Journal of Engineering Geology,2008,16(4):433～444.
[17]Rodriguez,C.E.,Bommer,J.J.,Chandler,R.J..Earthquake induced landslides:19801997[J].Soil Dynamics Earthquake Engineering,1999,18,325～346.
[18]Jibson,R.W.,Harp,E.L.,Schulz,W.,Keefer,D.K..Landslides triggered by the2002Denali Fault,Alaska,earth-quake and the inferred nature of the strong shaking[J].Earth-quake Spectra,2004,20,669～691.
[19]Abrahamson N A,Somerville P G.Effects of the hanging wall and footwall on ground motions recorded during the Northridge earthquake[J].Bull Seism Soc Amer,1996,86(1B):S93～S99.
[20]俞言祥,高孟潭.台湾集集地震近场地震动的上盘效应[J].地震学报,2001,23(6):615～621.Yu Yanxing,Gao Mengtan.Effects of the hangingwall and foot-wall on peak acceleration during the Chi-Chi earthquake,Tai-wan.Acta Seismologica Sinica,2001,23(6):615～621.
[21]陈运泰.汶川地震何以如此严重[EB/OL].(2008-06-26).http://www.sciencenet.cn/htmlnews/2008/6/200862781145413208421.html.Chen Yuntai.Why was Wenchuan Earthquake so serious-(2008-06-26).http://www.sciencenet.cn/htmlnews/2008/6/200862781145413208421.html.
[22]陈运泰.汶川特大地震的震级和断层长度[J].科技导报,2008,26(10):26～27.Chen Yuntai.On the Magnitude and the fault length of the great Wenchuan Earthquake.Science&Technology Review,2008,26(10):26～27.
[2]黄润秋,李为乐.“5.12”汶川大地震触发地质灾害的发育分布规律研究[J].岩石力学与工程学报,2008,27(12).Huang Runqiu,Liweile.Astudy on the development and distribu-tion rules of geohazards triggered by“5.12”Wenchuan Earth-quake,2008,27(12).
[3]何宏林,孙昭民,王世元,等.汶川MS8.0地震地表破裂带[J].地震地质,2008,30(2):359～361.He honglin,Sun Shaomin,Wang Shiyuan,et al..Rupture of the MS8.0Wenchuan Earthquake.Seismology and Geology,2008,30(2):359～361.
[4]黄润秋,许强,等.中国典型灾难性滑坡[M].北京:科学出版社,2008.Huang Runqiu,Xu Qiang,et al..Catastrophic landslides in Chi-na.Beijing:Science Press,2008.
[5]Keefer,D.K..Landslides caused by earthquakes[J].Geol.Soc.Am.Bull.1984,95,406～421.
[6]Yao Qinglin.Study on earthquake-induced landslide hazards in loess region.M.S Paper at the Geological Institute,SSB,1986.
[7]李忠生.国内外地震滑坡灾害研究综述[J].灾害学,2003,18(4):64～70.Li Zhongsheng.The State of the art of the research on seismic landslide hazard at home and abroad.Journal of Catastrophology,2003,18(4):64～70.
[8]Slonenko,V.P..Landslides of collapses in seismic zone and other prediction.Bull of IAEG,1976,15.
[9]胡广韬.滑坡动力学[M].北京:地质出版社,1995.Hu Guangtao.Landslide dynamics.Beijing:Geological PublishingHouse,1995.
[10]毛彦龙,胡广韬,赵法锁,等.地震动触发滑坡体滑动的机理[J].西安工程学院学报,1998,20(4):45～48.Mao Yanlong,Hu Guangtao,Zhao Fasuo,et al..Mechanics of the landslide sliding caused by seismic.Journal of Xi′an Engi-neering University,1998,20(4):45～48.
[11]鲍叶静,高孟潭,姜慧.地震诱发滑坡的概率分析[J].岩石力学与工程学报,2005,24(1):66～70.Bao Yejing,Gao Mengtan,Jiang hui.Probabilistic analysis of earthquake-induced landslides.Chinese Journal of Rock Me-chanics and Engineering,2005,24(1):66～70.
[12]Keefer D V.Statistical analysis of an earthquake-induced land-slide distribution the1989Loma Prieta,California event[J].Engineering Geology,2000,58,231～249.
[13]Jibson R W,Harp E L,and Michael J A.Amethod for producing digital probabilistic seismic landslide hazard maps[J].Engineer-ing Geology,Special Issue,2000,(58):3～4.
[14]Mohammad R.Mahdavifar,Shahryar Solaymani,Mohammad K.Jafari.Landslides triggered by the Avaj,Iran earthquake of June22,2002[J].Engineering Geology,2006,86,166～182.
[15]Wang W N,Nakamura H,Tsuchiya S,Chen C C.Distributions of landslides triggered by the Chi-Chi earthquake in Central Tai-wan on September21,1999[J].Journal of the Japan Landslide Society,2002,38(4):318～326.
[16]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433～444.Yin Yaoping.Researches on the geo-hazards triggered by Wen-chuan Earthquake,Sichuan.Journal of Engineering Geology,2008,16(4):433～444.
[17]Rodriguez,C.E.,Bommer,J.J.,Chandler,R.J..Earthquake induced landslides:19801997[J].Soil Dynamics Earthquake Engineering,1999,18,325～346.
[18]Jibson,R.W.,Harp,E.L.,Schulz,W.,Keefer,D.K..Landslides triggered by the2002Denali Fault,Alaska,earth-quake and the inferred nature of the strong shaking[J].Earth-quake Spectra,2004,20,669～691.
[19]Abrahamson N A,Somerville P G.Effects of the hanging wall and footwall on ground motions recorded during the Northridge earthquake[J].Bull Seism Soc Amer,1996,86(1B):S93～S99.
[20]俞言祥,高孟潭.台湾集集地震近场地震动的上盘效应[J].地震学报,2001,23(6):615～621.Yu Yanxing,Gao Mengtan.Effects of the hangingwall and foot-wall on peak acceleration during the Chi-Chi earthquake,Tai-wan.Acta Seismologica Sinica,2001,23(6):615～621.
[21]陈运泰.汶川地震何以如此严重[EB/OL].(2008-06-26).http://www.sciencenet.cn/htmlnews/2008/6/200862781145413208421.html.Chen Yuntai.Why was Wenchuan Earthquake so serious-(2008-06-26).http://www.sciencenet.cn/htmlnews/2008/6/200862781145413208421.html.
[22]陈运泰.汶川特大地震的震级和断层长度[J].科技导报,2008,26(10):26～27.Chen Yuntai.On the Magnitude and the fault length of the great Wenchuan Earthquake.Science&Technology Review,2008,26(10):26～27.
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