龙山门断裂带活动特征与工程区域地壳稳定性评价理论
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摘要
2008年5月12日发生的里氏8.0级汶川地震处于龙门山造山带与四川盆地的构造边界上。350km长的地表破裂带呈右行左阶雁行排列在具有逆冲和右行走滑性质的汶川—茂县—青川、映秀—北川和江油—都江堰3条断层带上。下地壳的韧性流动伴随中地壳韧-脆性剪切带应力和应变的积累,产生上地壳脆性发震断层,并控制地表破裂带和滑坡的分布。震源出现在上地壳脆性断层与中地壳脆-韧性剪切带的交汇部位。以汶川地震为例,结合板内地震基本特征,提出引入大陆动力学理论完善工程区域稳定性理论基础,构建基于板块学说、地质力学和大陆动力学理论的相互补充的工程区域稳定性评价体系;对活断层与地震活动性预测提出见解,强调仅仅从活断层的存在及其活动强度来预测地震活动性与强度是远远不够甚至是错误的,必须将下地壳、中地壳和上地壳结构作为一个整体加以研究和判别;提出工程区域地壳稳定性评价指标体系,指出了大陆内部"安全岛"划分应采用的核心指标。
The Wenchuan earthquake of May 12th,2008 on the tectonic margin between the Longmenshan orogenic belt and Sichuan basin had a magnitude of 8.0 Ms,on the Yingxiu-Beichuan fault.A 350-km-long surface rupture zone exhibits right-lateral and left-step features.It is related to the west-dip Wenchuan-Maowen-Qingchuan fault,Yingxiu-Beichuan fault and the Jiangyou-Dujiangyan fault which show dextral strike-slip and thrust.The brittle seismogenic faults in the upper crust,which controlled surface rupture zones and landslides,were produced by slowly ductile flow of lower crust with the stress and strain accumulation at the ductile-brittle shear zone of the middle crust.Seismic source locates at the connection spot between the ductile-brittle shear zone in middle crust and brittle active faults in upper crust.This paper examines the Wenchuan Earthquake in association with the basic characters of intra-plate earthquake.It is believed that it is necessary to develop the theory of regional stability for engineering by continental dynamic theory.The evaluating system must be established together by plate theory,geological mechanics and continental dynamic theory.Some opinions about active faults and earthquake prediction are discussed.It is stressed that earthquake prediction only by active fault is insufficient or improper.The causative structure in lower crust,ductile-brittle transition zone in middle crust and brittle seismogenic faults in upper crust must be considered as a whole in the study.At last,an evaluation index system of regional crustal stability for engineering projects is put forward and the key index for "safety island" is pointed out.
The Wenchuan earthquake of May 12th,2008 on the tectonic margin between the Longmenshan orogenic belt and Sichuan basin had a magnitude of 8.0 Ms,on the Yingxiu-Beichuan fault.A 350-km-long surface rupture zone exhibits right-lateral and left-step features.It is related to the west-dip Wenchuan-Maowen-Qingchuan fault,Yingxiu-Beichuan fault and the Jiangyou-Dujiangyan fault which show dextral strike-slip and thrust.The brittle seismogenic faults in the upper crust,which controlled surface rupture zones and landslides,were produced by slowly ductile flow of lower crust with the stress and strain accumulation at the ductile-brittle shear zone of the middle crust.Seismic source locates at the connection spot between the ductile-brittle shear zone in middle crust and brittle active faults in upper crust.This paper examines the Wenchuan Earthquake in association with the basic characters of intra-plate earthquake.It is believed that it is necessary to develop the theory of regional stability for engineering by continental dynamic theory.The evaluating system must be established together by plate theory,geological mechanics and continental dynamic theory.Some opinions about active faults and earthquake prediction are discussed.It is stressed that earthquake prediction only by active fault is insufficient or improper.The causative structure in lower crust,ductile-brittle transition zone in middle crust and brittle seismogenic faults in upper crust must be considered as a whole in the study.At last,an evaluation index system of regional crustal stability for engineering projects is put forward and the key index for "safety island" is pointed out.
引文
[1]王思敬,黄鼎成.中国工程地质世纪成就[M].北京:地质出版社,2004,43~57.Wang Sijing,Huang Dingcheng.Century achievement of engineer-ing geology in China.Geology Publishing House,2004,43~57.
[2]柴建峰,朱时杰,伍法权等.区域地壳稳定性研究现状与趋势[J].工程地质学报,2004,12(4):401~407.Chai Jianfeng,Zhu Shijie,et al..State of art:regional crustal sta-bility.Journal of Engineering Geology,2004,12(4):401~407.
[3]杜东菊.中国区域稳定工程地质学产生与发展[J].工程地质学报,1994,2(3):21~25.Du Dongju.Establishment and development of regional stability en-gineering.Journal of Engineering Geology,1994,2(3):21~25.
[4]吴树仁,韩金良,石菊松等.区域地壳稳定性研究现状和发展趋势[J].工程地质学报,2004,12(增):26~30.WU Shuren,Han Jinliang,Shi Jusong,et al..Progress and devel-op treng of the study on regional crustal stability in China.Journalof Engineering Geology,2004,12(Suppl.):26~30.
[5]彭建兵.区域稳定动力学研究(二)基本原则[J].工程地质学报,2001,9(1):12~16.Peng Jianbin.Fundamental principles for study on dynamics of re-gional stability.Journal of Engineering Geology,2001,9(1):12~16.
[6]李德威.大陆下地壳流动-层流还是渠流[J].地学前缘,2008,12(3):130~26.Li Dewei.Continental lower-crustal flow:channel flow or laminarflow.Earth Science Frontiers,2008,15(3):130~136.
[7]李德威.大陆板内地震的发震机理与地震预报———以汶川地震为例[J].地质科技情报,2008,27(5):1~6.Li Dewei.Mechanism and prediction of the intraplate earthquakes:an example from Wenchuan Earthquake in Sichuan Province.Geo-logical Information,2008,27(5):1~6.
[8]ROYDEN L H,BURCHFIEL B C,KING R W,et al..Surfacedeformation and lower crustal flow in eastern Tibet[J].Science,1997,(276):788~790.
[9]CLARK M K,ROYDEN L H.Topographic ooze:Building theeastern margin of Tibet by lower crustal flow[J].Geology,2000,(28):703~706.
[10]罗文行,李德威,汪校锋.青藏高原板内地震震源深度分布规律及其成因[J].地球科学-中国地质大学学报,2008,12(5):618~626.Lu Wenxing,Li Dewei,Wang Xiaofeng.Focal depth and mecha-nism of intraplate earthquakes in the Qinghai-Tibet Plateau.Earth Science,2008,33(5):618~626.
[11]胡海涛,殷跃平.区域地壳稳定性评价安全岛理论及方法[J].地学前缘(中国地质大学.北京),1996,3(1~2):57~68.Hu Haitao,Yin Yueping,The theory and method of evaluation ofreginal crustal stability based on concept of"Ssafe island".EarthScience Frontiers,1996,3(1~2):57~68.
[2]柴建峰,朱时杰,伍法权等.区域地壳稳定性研究现状与趋势[J].工程地质学报,2004,12(4):401~407.Chai Jianfeng,Zhu Shijie,et al..State of art:regional crustal sta-bility.Journal of Engineering Geology,2004,12(4):401~407.
[3]杜东菊.中国区域稳定工程地质学产生与发展[J].工程地质学报,1994,2(3):21~25.Du Dongju.Establishment and development of regional stability en-gineering.Journal of Engineering Geology,1994,2(3):21~25.
[4]吴树仁,韩金良,石菊松等.区域地壳稳定性研究现状和发展趋势[J].工程地质学报,2004,12(增):26~30.WU Shuren,Han Jinliang,Shi Jusong,et al..Progress and devel-op treng of the study on regional crustal stability in China.Journalof Engineering Geology,2004,12(Suppl.):26~30.
[5]彭建兵.区域稳定动力学研究(二)基本原则[J].工程地质学报,2001,9(1):12~16.Peng Jianbin.Fundamental principles for study on dynamics of re-gional stability.Journal of Engineering Geology,2001,9(1):12~16.
[6]李德威.大陆下地壳流动-层流还是渠流[J].地学前缘,2008,12(3):130~26.Li Dewei.Continental lower-crustal flow:channel flow or laminarflow.Earth Science Frontiers,2008,15(3):130~136.
[7]李德威.大陆板内地震的发震机理与地震预报———以汶川地震为例[J].地质科技情报,2008,27(5):1~6.Li Dewei.Mechanism and prediction of the intraplate earthquakes:an example from Wenchuan Earthquake in Sichuan Province.Geo-logical Information,2008,27(5):1~6.
[8]ROYDEN L H,BURCHFIEL B C,KING R W,et al..Surfacedeformation and lower crustal flow in eastern Tibet[J].Science,1997,(276):788~790.
[9]CLARK M K,ROYDEN L H.Topographic ooze:Building theeastern margin of Tibet by lower crustal flow[J].Geology,2000,(28):703~706.
[10]罗文行,李德威,汪校锋.青藏高原板内地震震源深度分布规律及其成因[J].地球科学-中国地质大学学报,2008,12(5):618~626.Lu Wenxing,Li Dewei,Wang Xiaofeng.Focal depth and mecha-nism of intraplate earthquakes in the Qinghai-Tibet Plateau.Earth Science,2008,33(5):618~626.
[11]胡海涛,殷跃平.区域地壳稳定性评价安全岛理论及方法[J].地学前缘(中国地质大学.北京),1996,3(1~2):57~68.Hu Haitao,Yin Yueping,The theory and method of evaluation ofreginal crustal stability based on concept of"Ssafe island".EarthScience Frontiers,1996,3(1~2):57~68.
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