5.12汶川8级地震次生地质灾害的基本特征及其形成机制浅析
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摘要
5.12汶川8级大地震沿龙门山断裂带形成长350多km,宽约50km的地表破裂带,触发了1万多处崩塌、滑坡、泥石流(碎屑流)地质灾害,其中巨型灾害体87处、大型灾害体606处,形成了136个较大规模的堰塞湖。地震地质灾害的链生特征显著,形成地震-崩塌、地震-滑坡-碎屑流-堰塞湖-堰塞坝溃决-泥石流等典型地质灾害链。地震次生地质灾害具有分布范围广、数量多、种类全、密度大、强度高、致灾重的特点。在部分地区,崩塌、滑坡和碎屑流的分布面积占地震极重灾区面积的30%～58%,甚至高达80%。据初步统计,崩塌、滑坡和碎屑流共导致大约2万人死亡,其中北川县老县城滑坡导致1600多人死亡。地震次生地质灾害主要沿断裂带、河谷和交通线分布。崩塌、滑坡的破裂源主要位于河流拐弯处靠近侵蚀岸一侧、山脊两侧及坡肩部位,这与上述部位对地震动峰值加速度的放大作用直接相关。地震次生地质灾害主要受地震动峰值加速度和地形控制,其次为岩性、斜坡结构、活动断裂、人类工程活动。许多大型崩塌、滑坡还具有高速远程的特征,部分崩塌、滑坡-碎屑流位移达数km,速度高达100～300m/s,其运动轨迹复杂多变,常常导致多处人员伤亡,是高山峡谷地区地质灾害风险评估和减灾防灾必须面临的新课题。根据上述情况,文中对汶川地震次生地质灾害的基本特征、分布规律和主要影响因素进行了初步总结,并对地震滑坡的形成机制和运动模式进行了初步探讨。首次提出高山峡谷地区单一斜坡上呈阶梯状多级滑动的群发性地震滑坡的形成模式:强烈地震往往引起剧烈的地面震动,而高陡的山脊及其坡肩部位对地震波具有明显的放大作用,因此,上述部位往往是地震滑坡的高易发地段,当地震动峰值加速度超过不稳定性斜坡的临界峰值加速度时,斜坡失稳破坏形成一系列的群发性滑坡,从上到下往往形成阶梯状多级滑动的滑坡群,此种模式适用于残坡积层、风化层地震滑坡和主滑面较缓的地震基岩滑坡。最后,指出了今后应重点研究的科学问题,并对防灾减灾措施提出了一些建议。
The Ms 8.0 May 12,2008 Wenchuan earthquake triggered landslides,rock collapses and debris flows at more than 18 000 sites,which directly caused about 20 000 fatalities.Landslides,rock collapses and debris flows were distributed along active faults,rivers,roads,highways and railways,forming geological hazards chains.The peak ground acceleration is the strongest influence parameter,the second is topography,and bedrock geology,geomorphology,human activity are factors controlling earthquake-induced landslides also.Rupture geneses of landslides and rock collapses clustered at or near ridge crests,and at convex knickpoint within ridge flanks,and it is found out that this topography had a strong effect on seismic waves,giving rise to a significant amplification of peak ground accelerations at those sites.We give a new model of rupture of landslides and rock collapses triggered by strong earthquake in mountainous area.
The Ms 8.0 May 12,2008 Wenchuan earthquake triggered landslides,rock collapses and debris flows at more than 18 000 sites,which directly caused about 20 000 fatalities.Landslides,rock collapses and debris flows were distributed along active faults,rivers,roads,highways and railways,forming geological hazards chains.The peak ground acceleration is the strongest influence parameter,the second is topography,and bedrock geology,geomorphology,human activity are factors controlling earthquake-induced landslides also.Rupture geneses of landslides and rock collapses clustered at or near ridge crests,and at convex knickpoint within ridge flanks,and it is found out that this topography had a strong effect on seismic waves,giving rise to a significant amplification of peak ground accelerations at those sites.We give a new model of rupture of landslides and rock collapses triggered by strong earthquake in mountainous area.
引文
[1]Wu S R,Shi J S,Yao X,et al.Analysis and evaluation of geohazard intensity of the Wenchuan earthquake,Sichuan[J].Geological Bulletin of China,2008,27(11):1753-1763(in Chinese).
[2]Lin L J,Fang C,Li XJ,et al.Primary analysis of geologic hazards in Wenchuan earthquake area[J].Hydrogeologyand Engineering Geology,2008,35(4):I-V(in Chinese).
[3]Wang Z H,Zhou Y J,Xu B,et al.Preliminary remote sensinginvestigation of damage caused by the“5.12”Wen-chuan strong earthquake as well as secondary hazards at the quake center—Yingxiu town[J].Remote Sensing for Land&Resources,2008,16(4):1-4(in Chinese).
[4]Yin Y P.Researches on the geo-hazards triggered by Wen-chuan earthquake,Sichuan[J].Journal of Engineering Ge-ology,2008,16(4):433-444(in Chinese).
[5]Dong L Q.Emergency remote sensing investigation of bar-rier lakes at the quake center are caused by“5.12”Wen-chuan strong earthquake[J].Remote Sensing for Land&Resources,2008,15(3):61-63(in Chinese).
[6]Chen X Q,Cui P,Cheng Z L,et al.Emergency risk as-sessment of dammed lakes by the Wenchuan earthquake on May12,2008[J].Earth Science Frontiers,2008,15(4):244-249(in Chinese).
[7]He HL,Zhang Z M,Wang S Y,et al.Rupture of theMs8.0Wenchuan earthquake[J].Seismology and Geology,2008,30(2):359-361(in Chinese).
[8]Zhang P Z,Xu X W,Wen X Z,et al.Slip rates and recur-rence intervals of the Longmen Shan active fault zone,and tectonic implications for the mechanismof the May12Wen-chuan earthquake,2008,Sichuan,China[J].Chinese Jour-nal of Geophysics,2008,51(4):1066-1073(in Chinese).
[9]Ma B Q,Zhang S M,Tian QJ,et al.The surface rupture of Wenchuan earthquake(Ms8.0)[J].Quaternary Science,2008,28(4):513-520(in Chinese).
[10]Monitoring and Prediction Depart ment,Chinese Earthquake Administration.The Record of Unrevised Peak Ground Ac-celeration of Wenchuan Earthquake with a Moment Magni-tude of8.0[M].Beijing:Seismological Press,2008(in Chi-nese).
[11]Yang Z E,Deng Z H,Ma W T,et al.Some destruction andits seismicintensityin meizoseismal region of Wenchuan earthquake with magnitude8,Sichuan,China[J].Seismol-ogy and Geology,2008,30(2):349-354(in Chinese).
[12]Jibson R W,Harp E L,Willian S,et al.Large rock ava-lanches triggered by theMs7.9Denali Fault,Alaska,earthquake of3November2002[J].Engineering Geology,2006(83):144-160.
[13]Meunier P,Hovius N,Haines J A.Topographic site effects and the location of earthquake induced landslides[J].Earth and Planetary Science Letters,2008,275:221-232.
[14]Owena L A,Kamp U,Khattak G A,et al.Landslides trig-gered by the8October2005Kashmir earthquake[J].Geo-morphology,2008,94:1-9.
[15]Dunning S A,Mitchell WA,Rosser NJ,et al.The Hatti-an Bala rock avalanche and associatedlandslides triggered by the Kashmir Earthquake of8October2005[J].EngineeringGeology,2007(93):130-144.
[16]Bourdeaua C,Havenith HB.Site effects modelling applied to the slope affected by the Suusamyr earthquake(Kyrgy-zstan,1992)[J].Engineering Geology,2008(97):126-145.
[17]Xu G X,Yao J K,Gao Z N,et al.Large-scale shaking ta-ble model test study on dynamic characteristics and dynamic responses of slope[J].Chinese Journal of Rocks Mechanics and Engineering,2008,27(3):624-632(in Chinese).
[18]Mao Y L,Hu G T,Mao X H,et al.Mechanismof set-out violent-slide of slope mass during earthquake andits simula-tion by using discrete element method[J].Journal of Engi-neering Geology,2001,9(1):74-80(in Chinese).
[19]Yan E C,Liu H C,Tang H M,et al.Experimental study on the dynamic properties of soil in slide zone of landslide[J].Journal of Engineering Geology,2003,11(3):318-322(in Chinese).
[20]Cheng Q G,Zhang Z Y,Huang R Q.Study on dynamics of rock avalanches:State of the art report[J].Journal of Mountain Science,2007,25(1):72-84(in Chinese).
[21]Han J L,Wu S R,Wang H B.Preliminary study on geo-logical hazard chains[J].Earth Science Frontiers,2007,14(6):11-23(in Chinese).
[1]吴树仁,石菊松,姚鑫,等.四川汶川大地震地质灾害活动强度分析评价[J].地质通报,2008,27(11):1753-1763.
[2]林良俊,方成,李小杰,等.5.12汶川地震灾区地质灾害情况初步分析[J].水文地质工程地质,2008,35(4):I-V.
[3]王治华,周英杰,徐斌,等.“5.12”汶川大地震震中区映秀镇地震灾情及次生地质灾害遥感初步调查[J].国土资源遥感,2008,16(4):1-4.
[4]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.
[5]童立强.“5.12”汶川大地震极重灾区地震堰塞湖应急遥感调查[J].国土资源遥感,2008,15(3):61-63.
[6]陈晓清,崔鹏,程尊兰,等.5.12汶川地震堰塞湖危险性应急评估[J].地学前缘,2008,15(4):244-249.
[7]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.
[8]张培震,徐锡伟,闻学泽,等.2008年汶川8级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1066-1073.
[9]马保起,张世民,田勤俭,等.汶川8.0级地震地表破裂带[J].第四纪研究,2008,28(4):513-520.
[10]中国地震局灾害防御司.汶川8.0级地震未校正加速度记录[M].北京:地震出版社,2008.
[11]杨主恩,邓志辉,马文涛,等.汶川8级强震极震区破坏情况与烈度[J].地震地质,2008,30(2):349-354.
[17]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.
[18]毛彦龙,胡广韬,毛新虎,等.地震滑坡启程剧动的机理研究及离散元模拟[J].工程地质学报,2001,9(1):74-80.
[19]晏鄂川,刘汉超,唐辉明.滑带土动力学性质试验研究[J].工程地质学报,2003,11(3):318-322.
[20]程谦恭,张倬元,黄润秋.高速远程崩滑动力学的研究现状及发展趋势[J].山地学报,2007,25(1):72-84.
[21]韩金良,吴树仁,汪华斌.地质灾害链[J].地学前缘,2007,14(6):11-23.
[2]Lin L J,Fang C,Li XJ,et al.Primary analysis of geologic hazards in Wenchuan earthquake area[J].Hydrogeologyand Engineering Geology,2008,35(4):I-V(in Chinese).
[3]Wang Z H,Zhou Y J,Xu B,et al.Preliminary remote sensinginvestigation of damage caused by the“5.12”Wen-chuan strong earthquake as well as secondary hazards at the quake center—Yingxiu town[J].Remote Sensing for Land&Resources,2008,16(4):1-4(in Chinese).
[4]Yin Y P.Researches on the geo-hazards triggered by Wen-chuan earthquake,Sichuan[J].Journal of Engineering Ge-ology,2008,16(4):433-444(in Chinese).
[5]Dong L Q.Emergency remote sensing investigation of bar-rier lakes at the quake center are caused by“5.12”Wen-chuan strong earthquake[J].Remote Sensing for Land&Resources,2008,15(3):61-63(in Chinese).
[6]Chen X Q,Cui P,Cheng Z L,et al.Emergency risk as-sessment of dammed lakes by the Wenchuan earthquake on May12,2008[J].Earth Science Frontiers,2008,15(4):244-249(in Chinese).
[7]He HL,Zhang Z M,Wang S Y,et al.Rupture of theMs8.0Wenchuan earthquake[J].Seismology and Geology,2008,30(2):359-361(in Chinese).
[8]Zhang P Z,Xu X W,Wen X Z,et al.Slip rates and recur-rence intervals of the Longmen Shan active fault zone,and tectonic implications for the mechanismof the May12Wen-chuan earthquake,2008,Sichuan,China[J].Chinese Jour-nal of Geophysics,2008,51(4):1066-1073(in Chinese).
[9]Ma B Q,Zhang S M,Tian QJ,et al.The surface rupture of Wenchuan earthquake(Ms8.0)[J].Quaternary Science,2008,28(4):513-520(in Chinese).
[10]Monitoring and Prediction Depart ment,Chinese Earthquake Administration.The Record of Unrevised Peak Ground Ac-celeration of Wenchuan Earthquake with a Moment Magni-tude of8.0[M].Beijing:Seismological Press,2008(in Chi-nese).
[11]Yang Z E,Deng Z H,Ma W T,et al.Some destruction andits seismicintensityin meizoseismal region of Wenchuan earthquake with magnitude8,Sichuan,China[J].Seismol-ogy and Geology,2008,30(2):349-354(in Chinese).
[12]Jibson R W,Harp E L,Willian S,et al.Large rock ava-lanches triggered by theMs7.9Denali Fault,Alaska,earthquake of3November2002[J].Engineering Geology,2006(83):144-160.
[13]Meunier P,Hovius N,Haines J A.Topographic site effects and the location of earthquake induced landslides[J].Earth and Planetary Science Letters,2008,275:221-232.
[14]Owena L A,Kamp U,Khattak G A,et al.Landslides trig-gered by the8October2005Kashmir earthquake[J].Geo-morphology,2008,94:1-9.
[15]Dunning S A,Mitchell WA,Rosser NJ,et al.The Hatti-an Bala rock avalanche and associatedlandslides triggered by the Kashmir Earthquake of8October2005[J].EngineeringGeology,2007(93):130-144.
[16]Bourdeaua C,Havenith HB.Site effects modelling applied to the slope affected by the Suusamyr earthquake(Kyrgy-zstan,1992)[J].Engineering Geology,2008(97):126-145.
[17]Xu G X,Yao J K,Gao Z N,et al.Large-scale shaking ta-ble model test study on dynamic characteristics and dynamic responses of slope[J].Chinese Journal of Rocks Mechanics and Engineering,2008,27(3):624-632(in Chinese).
[18]Mao Y L,Hu G T,Mao X H,et al.Mechanismof set-out violent-slide of slope mass during earthquake andits simula-tion by using discrete element method[J].Journal of Engi-neering Geology,2001,9(1):74-80(in Chinese).
[19]Yan E C,Liu H C,Tang H M,et al.Experimental study on the dynamic properties of soil in slide zone of landslide[J].Journal of Engineering Geology,2003,11(3):318-322(in Chinese).
[20]Cheng Q G,Zhang Z Y,Huang R Q.Study on dynamics of rock avalanches:State of the art report[J].Journal of Mountain Science,2007,25(1):72-84(in Chinese).
[21]Han J L,Wu S R,Wang H B.Preliminary study on geo-logical hazard chains[J].Earth Science Frontiers,2007,14(6):11-23(in Chinese).
[1]吴树仁,石菊松,姚鑫,等.四川汶川大地震地质灾害活动强度分析评价[J].地质通报,2008,27(11):1753-1763.
[2]林良俊,方成,李小杰,等.5.12汶川地震灾区地质灾害情况初步分析[J].水文地质工程地质,2008,35(4):I-V.
[3]王治华,周英杰,徐斌,等.“5.12”汶川大地震震中区映秀镇地震灾情及次生地质灾害遥感初步调查[J].国土资源遥感,2008,16(4):1-4.
[4]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.
[5]童立强.“5.12”汶川大地震极重灾区地震堰塞湖应急遥感调查[J].国土资源遥感,2008,15(3):61-63.
[6]陈晓清,崔鹏,程尊兰,等.5.12汶川地震堰塞湖危险性应急评估[J].地学前缘,2008,15(4):244-249.
[7]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.
[8]张培震,徐锡伟,闻学泽,等.2008年汶川8级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1066-1073.
[9]马保起,张世民,田勤俭,等.汶川8.0级地震地表破裂带[J].第四纪研究,2008,28(4):513-520.
[10]中国地震局灾害防御司.汶川8.0级地震未校正加速度记录[M].北京:地震出版社,2008.
[11]杨主恩,邓志辉,马文涛,等.汶川8级强震极震区破坏情况与烈度[J].地震地质,2008,30(2):349-354.
[17]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.
[18]毛彦龙,胡广韬,毛新虎,等.地震滑坡启程剧动的机理研究及离散元模拟[J].工程地质学报,2001,9(1):74-80.
[19]晏鄂川,刘汉超,唐辉明.滑带土动力学性质试验研究[J].工程地质学报,2003,11(3):318-322.
[20]程谦恭,张倬元,黄润秋.高速远程崩滑动力学的研究现状及发展趋势[J].山地学报,2007,25(1):72-84.
[21]韩金良,吴树仁,汪华斌.地质灾害链[J].地学前缘,2007,14(6):11-23.
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