从地质特征分析成都主城区在地震中的安全性——以汶川大地震为例
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摘要
汶川M_S 8.0大地震发生后,关于成都市主城区安全性的讨论一度十分激烈。本文从成都市及周边的基本地质构造和沉积特征入手,讨论成都市主城区在地震中的安全性问题。经过分析认为:川西坳陷刚性稳定的岩石圈结构决定了成都平原不会发生破坏性的大地震;成都平原沉积盖层厚度大、质量佳、分布适宜决定了龙门山发生的地震不会对成都主城区造成巨大破坏。因此,面对天然地震,成都市主城区是安全的。
The earthquake safety of the Chengdu city has been a focus issue since the Wenchuan big earthquake. This present paper will talk about the safety of Chengdu urban area in an earthquake based on the basic geological structures and sedimentary features in Chengdu and its neighborhood area. Devastating earthquakes usually occur at active huge fault belts,and are of repetitive. The lithosphere structure of western Sichuan depression( Chengdu plain) is rigid and stable. Being situated at Chengdu plain, Chengdu city is on a stable tectonic unit. There is no large fault under the city. There is no record about devastating earthquake in Chengdu plain in history. Thus, there is no any possibility for a devastating earthquake to occur at Chengdu city. Secondly, Chengdu plain has a thick , good and well-distributed sedimentary cover, which determines that any earthquake occurs in Longmenshan can not make fatal damage to Chengdu urban area. The strata under Chengdu plain are composed up of four layers: 1) The Pre-Sinian basement, whose surface is buried 11 kilometers and is the deepest in Sichuan Basin; 2) Upper Sinian-Middle Triassic marine carbonates with the thickness of 4 000 m to 5 000 m; 3) Uupper Triassic-Cretaceous continental clastic rocks with the thickest thickness of 5 000 m to 6 000 m in Sichuan Basin. This strata texture is "the protection god" warding the Chengdu city off being ruined by Wenchuan earthquake. Because the rigidity of the strata becomes smaller and smaller from the bottom to the top, their ability absorbing the seismic energy resulted by earthquakes is bigger and bigger. This makes the seismic waves from Longmen Mountain earthquakes very weak with no destroy energy when they propagated to Chengdu city. Therefore, Chengdu city is safe to the earthquakes which happen in Longmen Mountains. There, faced with natural earthquake, Chengdu urban area are safe.
The earthquake safety of the Chengdu city has been a focus issue since the Wenchuan big earthquake. This present paper will talk about the safety of Chengdu urban area in an earthquake based on the basic geological structures and sedimentary features in Chengdu and its neighborhood area. Devastating earthquakes usually occur at active huge fault belts,and are of repetitive. The lithosphere structure of western Sichuan depression( Chengdu plain) is rigid and stable. Being situated at Chengdu plain, Chengdu city is on a stable tectonic unit. There is no large fault under the city. There is no record about devastating earthquake in Chengdu plain in history. Thus, there is no any possibility for a devastating earthquake to occur at Chengdu city. Secondly, Chengdu plain has a thick , good and well-distributed sedimentary cover, which determines that any earthquake occurs in Longmenshan can not make fatal damage to Chengdu urban area. The strata under Chengdu plain are composed up of four layers: 1) The Pre-Sinian basement, whose surface is buried 11 kilometers and is the deepest in Sichuan Basin; 2) Upper Sinian-Middle Triassic marine carbonates with the thickness of 4 000 m to 5 000 m; 3) Uupper Triassic-Cretaceous continental clastic rocks with the thickest thickness of 5 000 m to 6 000 m in Sichuan Basin. This strata texture is "the protection god" warding the Chengdu city off being ruined by Wenchuan earthquake. Because the rigidity of the strata becomes smaller and smaller from the bottom to the top, their ability absorbing the seismic energy resulted by earthquakes is bigger and bigger. This makes the seismic waves from Longmen Mountain earthquakes very weak with no destroy energy when they propagated to Chengdu city. Therefore, Chengdu city is safe to the earthquakes which happen in Longmen Mountains. There, faced with natural earthquake, Chengdu urban area are safe.
引文
① 倪师军,曹俊兴,刘树根等.2008． 成都市国土资源局--汶川“5． 12”大地震与成都地质环境论坛专题:成都主城区地震安全性的地质构造[E/OL].
董绍鹏,韩竹军,尹金辉,李峰,安艳芬.2008． 龙门山山前大邑断裂活动时代与最新构造变形样式初步研究.地震地质,30(4) :996-1003．Dong Shaopeng,Han Zhujun,Yin Jinhui,Li Feng and An Yanfen.2008． A Preliminary research on the latest tectonic deformation style and the activity age of the Dayi fault in the piedmont of the Longmen Mountains.Seismology and Geology,30(4) :996-1003．
郭正吾,邓康龄,韩永辉.1996． 四川盆地形成与演化.北京:地质出版社.48-62． Guo Zhengwu,Deng Kangling and Han Yonghui.1996． The Fomation and Development of Sichuan Basin.Beijing:Geological Publishing House.
洪时中.2008． 汶川大地震与成都地区的地震安全性.四川地震,129(4) :5-11． Hong Shizhong.2008． The M_S 8． 0 Wenchuan earthquake and seismic safety of the Chengdu area.Earthquake Research in Sichuan,129(4) :5-11．
黄祖智,唐荣昌.1995． 龙泉山活动断裂带及其潜在地震能力的探讨.四川地震,(1) :18-23． Huang Zuzhi and Tang Rongchang.1995． The Longquanshan fault zone and exploration of potential earthquake ability.Earthquake Research in Sichuan,(1) :18-23．
嵇少丞,王茜,孙圣思,许志琴,李海兵.2008． 亚洲大陆逃逸构造与现今中国地震活动.地质学报,82(12) :1644-1667． Ji Shaocheng,Wang Qian,Sun Shengsi,Xu Zhiqin and Li Haibing.2008． Continental extrusion and seismicity in China.Acta Geologica Sinica,82(12) :1644-1667．
李勇,曾允孚,伊海生.1995． 龙门山前陆盆地沉积及构造演化成都.成都科技大学出版社.1-91． Li Yong,Zeng Yongfu and Yi Haisheng.1995． Sedimentary and Tectonic Evolution of the Longmenshan Foreland Basin,Western Sichuan,China.Chengdu:Press of Chengdu University of Science and Technology.1-91．
刘福田,曲克信,吴华,李强,刘建华,胡戈.1989． 中国大陆及其邻近地区的地震层析成象.地球物理学报,32(3) :281-291． Liu Futian,Qu Kexin,Wu Hua,Li Qiang,Liu Jianhua and Hu Ge.1989． Seismic tomography of the Chinese continent and adjacent region.Chinese Journal of Geophysics(Acta Geophysica Sinica),32(3) :281-291．
刘建华,朱西养,王四利,魏继生.2005． 四川盆地地质构造演化特征与可地浸砂岩型铀矿找矿前景.铀矿地质,21(6) :321-330Liu Jianhua,Zhu Xiyang,Wang Sili and Wei Jisheng.2005． Geologic-tectonic evolutional characteristics and prospecting potential for ISL-amenable sandstone-type uranium deposits in Sichuan Basin.Uranium Geology,21(6) :321-330．
刘树根.1993龙门山冲断带与川西前陆盆地的形成演化.成都:成都科技大学出版社.46-64Liu Shugen.1993． The Formation and Evolution of Longmenshan Thrust Zone and Western Sichuan Foreland Basin,Sichuan,China.Chengdu:Press of Chengdu University of Science and Tecnology.46-64．
刘树根,童崇光,罗志立,戴苏兰,庞家黎,张国政,何军.1995． 川西晚三叠世前陆盆地的形成与演化.天然气工业,15(2) :11-15． Liu Shugen,Tong Chongguang,Luo Zhili,Dai Sulan,Pang Jiali,Zhang Guozheng and He Jun.1995． The formation and evolution of Late Triassic foreland basin in west Sichuan.Natural Gas Industry,15(2) :11-15．
罗志立.1986． 川中是一个古陆核吗?龙门山造山带的崛起和四川盆地的形成与演化.成都:成都科技大学出版社.386-393Luo Zhili.1986． Is There a Paleocontinental Neucleus in Central Sichuan?Uplift of Longmen Mountain Orogenic Belt and the Formation and Evolution of Sichuan Basin.Chengdu:Press of Chengdu University Science and Technology.386-393．
罗志立.1998． 四川盆地基底结构的新认识.成都理工大学学报,25(2) :191-200． Luo Zhili.1998． New recognition of basement in Sichuan Basin.Journal of Chengdu University of Technology,25(2) :191-200．
宋洪彪,罗志立.1995． 四川盆地基底及深部地质结构研究的进展.地学前缘,2(4) :231-237．Song Hongbiao and Luo Zhili.1995． The study of the basement and deep geological structures of Sichuan Basin,China.Earth Science Frontiers,2(4) :231-237．
王二七,孟庆任.2008． 对龙门山中生代和新生代构造演化的讨论.中国科学(D辑),38(10) :1221-1233． Wang Erchie and Meng Qingren.2009． Mesozoic and Cenozoic tectonic evolution of the Longmenshan fault belt.Science in China(Series D),52(5) :579-592．
王伟涛,贾东,李传友,郑文俊,魏占玉.2008． 四川龙泉山断裂带变形特征及其活动性初步研究.地震地质,30(4) :968-979．Wang Weitao,Jia Dong,Li Chuanyou,Zheng Wenjun and Wei Zhanyu.2008． Preliminary investigation on deformation characteristics and activity of Longquanshan fault belt in Sichuan.Seismology and Geology,30(4) :968-979．
吴如山,安艺敬一,李裕澈.1993． 地震波的散射与衰减(上).北京:地震出版社.58-59． Wu Rushan,Anyi Jingyi and Li Yuche.1993． Seismic Wave Scattering Theory and Its Applications.Beijing:Earthquake Publishing House.58-59．
徐水森,任寰,宋杰.2006． 龙泉山断裂带地震活动性浅析.四川地震,119(2) :21-27． Xu Shuisen,Ren Huan and Song Jie.2006． Primary study on the seismicity along the faults of Longquanshan.Earthquake Research in Sichuan,119(2) :21-27．
袁庭栋.2008． 成都的幸福感刍议.西华大学学报(哲学社会科学版),27(1) :1-6． Yuan Tingdong.2008． On sense of happiness in Chengdu.Journal of Xihua University(Philosophy & Social Sciences),27(1) :1-6．
郑文俊,王伟涛,李传友,魏占玉,高翔.2008． 熊坡背斜构造变形与蒲江-新津断裂活动特征.地震地质,30(4) :957-967． Zheng Wenjun,Wang Weitao,Li Chuanyou,Wei Zhanyu and Gao Xiang.2008． The deformation of the Xiongpo anticline and the activity of Pujiang-Xinjin fault.Seismology and Geology,30(4) :957-967．
Burchfiel B C,Royden L H,Van Der Hilst R D,Hager B H,Chen Z,King R W,Li C,LüJ,Yao H and Kirby E.2008． A geological and geophysical context for the Wenchuan earthquake of 12 May 2008,Sichuan,People's Republic of China.GSA Today,18(7) :4-11．
Densmore A L,Ellis M A,Li Y,Zhou R J,Hancock G S and Richardson N.2007． Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26:TC4005．
Holt W E,Chamot-Rooke N,Pichon X Le,Haines A J,Shen-Tu B and Ren J.2000． Velocity field in Asia inferred from Quaternary fault slip rates and global positioning system observations.Journal of Geophysical Research,105(B8) :19185-19209．
Jia D,Wei G Q,Chen Z X,Li B L Zeng Q and Yang G.2006． Longmen Shan fold-thrust belt and its relation to the western Sichuan Basin in central China:New insights from hydrocarbon exploration.AAPG Bulletin,90(9) :1425-1447．
King R W,Shen F,Burehfiel B C,Royden L H,Wang E,Chen Z L,Liu Y P,Zhang X Y,Zhao J X and Li Y L.1997． Geodetic measurement of crustal motion in southwest China.Geology,25(2) :179-182．
Shen Z K,Lü J N,Wang M and Bürgmann R.2005． Contemporary crustal deformation around the southeast borderland of the Tibetan Plateau.Journal of Geophysical Research,110:B11409．
Wang Q,Zhang P Z,Freymueller J T,Bilham R,Larson K M,Lai X A,You X Z,Niu Z J,Wu J C,Li Y X,Liu J N,Yang Z Q and Chen Q Z.2001． Present-day crustal deformation in China constrained by global position system measurements.Science,294(5542) :574-577．
Zhang P Z,Shen Z,Wang M,Gan W J,Burgmann R,Molnar P,Wang Q,Niu Z J,Sun J Z,Wu J C,Sun H R and You X Z.2004． Continuous deformation of the Tibetan Plateau from global positioning system data.Geology,32(9) :809-812．
董绍鹏,韩竹军,尹金辉,李峰,安艳芬.2008． 龙门山山前大邑断裂活动时代与最新构造变形样式初步研究.地震地质,30(4) :996-1003．Dong Shaopeng,Han Zhujun,Yin Jinhui,Li Feng and An Yanfen.2008． A Preliminary research on the latest tectonic deformation style and the activity age of the Dayi fault in the piedmont of the Longmen Mountains.Seismology and Geology,30(4) :996-1003．
郭正吾,邓康龄,韩永辉.1996． 四川盆地形成与演化.北京:地质出版社.48-62． Guo Zhengwu,Deng Kangling and Han Yonghui.1996． The Fomation and Development of Sichuan Basin.Beijing:Geological Publishing House.
洪时中.2008． 汶川大地震与成都地区的地震安全性.四川地震,129(4) :5-11． Hong Shizhong.2008． The M_S 8． 0 Wenchuan earthquake and seismic safety of the Chengdu area.Earthquake Research in Sichuan,129(4) :5-11．
黄祖智,唐荣昌.1995． 龙泉山活动断裂带及其潜在地震能力的探讨.四川地震,(1) :18-23． Huang Zuzhi and Tang Rongchang.1995． The Longquanshan fault zone and exploration of potential earthquake ability.Earthquake Research in Sichuan,(1) :18-23．
嵇少丞,王茜,孙圣思,许志琴,李海兵.2008． 亚洲大陆逃逸构造与现今中国地震活动.地质学报,82(12) :1644-1667． Ji Shaocheng,Wang Qian,Sun Shengsi,Xu Zhiqin and Li Haibing.2008． Continental extrusion and seismicity in China.Acta Geologica Sinica,82(12) :1644-1667．
李勇,曾允孚,伊海生.1995． 龙门山前陆盆地沉积及构造演化成都.成都科技大学出版社.1-91． Li Yong,Zeng Yongfu and Yi Haisheng.1995． Sedimentary and Tectonic Evolution of the Longmenshan Foreland Basin,Western Sichuan,China.Chengdu:Press of Chengdu University of Science and Technology.1-91．
刘福田,曲克信,吴华,李强,刘建华,胡戈.1989． 中国大陆及其邻近地区的地震层析成象.地球物理学报,32(3) :281-291． Liu Futian,Qu Kexin,Wu Hua,Li Qiang,Liu Jianhua and Hu Ge.1989． Seismic tomography of the Chinese continent and adjacent region.Chinese Journal of Geophysics(Acta Geophysica Sinica),32(3) :281-291．
刘建华,朱西养,王四利,魏继生.2005． 四川盆地地质构造演化特征与可地浸砂岩型铀矿找矿前景.铀矿地质,21(6) :321-330Liu Jianhua,Zhu Xiyang,Wang Sili and Wei Jisheng.2005． Geologic-tectonic evolutional characteristics and prospecting potential for ISL-amenable sandstone-type uranium deposits in Sichuan Basin.Uranium Geology,21(6) :321-330．
刘树根.1993龙门山冲断带与川西前陆盆地的形成演化.成都:成都科技大学出版社.46-64Liu Shugen.1993． The Formation and Evolution of Longmenshan Thrust Zone and Western Sichuan Foreland Basin,Sichuan,China.Chengdu:Press of Chengdu University of Science and Tecnology.46-64．
刘树根,童崇光,罗志立,戴苏兰,庞家黎,张国政,何军.1995． 川西晚三叠世前陆盆地的形成与演化.天然气工业,15(2) :11-15． Liu Shugen,Tong Chongguang,Luo Zhili,Dai Sulan,Pang Jiali,Zhang Guozheng and He Jun.1995． The formation and evolution of Late Triassic foreland basin in west Sichuan.Natural Gas Industry,15(2) :11-15．
罗志立.1986． 川中是一个古陆核吗?龙门山造山带的崛起和四川盆地的形成与演化.成都:成都科技大学出版社.386-393Luo Zhili.1986． Is There a Paleocontinental Neucleus in Central Sichuan?Uplift of Longmen Mountain Orogenic Belt and the Formation and Evolution of Sichuan Basin.Chengdu:Press of Chengdu University Science and Technology.386-393．
罗志立.1998． 四川盆地基底结构的新认识.成都理工大学学报,25(2) :191-200． Luo Zhili.1998． New recognition of basement in Sichuan Basin.Journal of Chengdu University of Technology,25(2) :191-200．
宋洪彪,罗志立.1995． 四川盆地基底及深部地质结构研究的进展.地学前缘,2(4) :231-237．Song Hongbiao and Luo Zhili.1995． The study of the basement and deep geological structures of Sichuan Basin,China.Earth Science Frontiers,2(4) :231-237．
王二七,孟庆任.2008． 对龙门山中生代和新生代构造演化的讨论.中国科学(D辑),38(10) :1221-1233． Wang Erchie and Meng Qingren.2009． Mesozoic and Cenozoic tectonic evolution of the Longmenshan fault belt.Science in China(Series D),52(5) :579-592．
王伟涛,贾东,李传友,郑文俊,魏占玉.2008． 四川龙泉山断裂带变形特征及其活动性初步研究.地震地质,30(4) :968-979．Wang Weitao,Jia Dong,Li Chuanyou,Zheng Wenjun and Wei Zhanyu.2008． Preliminary investigation on deformation characteristics and activity of Longquanshan fault belt in Sichuan.Seismology and Geology,30(4) :968-979．
吴如山,安艺敬一,李裕澈.1993． 地震波的散射与衰减(上).北京:地震出版社.58-59． Wu Rushan,Anyi Jingyi and Li Yuche.1993． Seismic Wave Scattering Theory and Its Applications.Beijing:Earthquake Publishing House.58-59．
徐水森,任寰,宋杰.2006． 龙泉山断裂带地震活动性浅析.四川地震,119(2) :21-27． Xu Shuisen,Ren Huan and Song Jie.2006． Primary study on the seismicity along the faults of Longquanshan.Earthquake Research in Sichuan,119(2) :21-27．
袁庭栋.2008． 成都的幸福感刍议.西华大学学报(哲学社会科学版),27(1) :1-6． Yuan Tingdong.2008． On sense of happiness in Chengdu.Journal of Xihua University(Philosophy & Social Sciences),27(1) :1-6．
郑文俊,王伟涛,李传友,魏占玉,高翔.2008． 熊坡背斜构造变形与蒲江-新津断裂活动特征.地震地质,30(4) :957-967． Zheng Wenjun,Wang Weitao,Li Chuanyou,Wei Zhanyu and Gao Xiang.2008． The deformation of the Xiongpo anticline and the activity of Pujiang-Xinjin fault.Seismology and Geology,30(4) :957-967．
Burchfiel B C,Royden L H,Van Der Hilst R D,Hager B H,Chen Z,King R W,Li C,LüJ,Yao H and Kirby E.2008． A geological and geophysical context for the Wenchuan earthquake of 12 May 2008,Sichuan,People's Republic of China.GSA Today,18(7) :4-11．
Densmore A L,Ellis M A,Li Y,Zhou R J,Hancock G S and Richardson N.2007． Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26:TC4005．
Holt W E,Chamot-Rooke N,Pichon X Le,Haines A J,Shen-Tu B and Ren J.2000． Velocity field in Asia inferred from Quaternary fault slip rates and global positioning system observations.Journal of Geophysical Research,105(B8) :19185-19209．
Jia D,Wei G Q,Chen Z X,Li B L Zeng Q and Yang G.2006． Longmen Shan fold-thrust belt and its relation to the western Sichuan Basin in central China:New insights from hydrocarbon exploration.AAPG Bulletin,90(9) :1425-1447．
King R W,Shen F,Burehfiel B C,Royden L H,Wang E,Chen Z L,Liu Y P,Zhang X Y,Zhao J X and Li Y L.1997． Geodetic measurement of crustal motion in southwest China.Geology,25(2) :179-182．
Shen Z K,Lü J N,Wang M and Bürgmann R.2005． Contemporary crustal deformation around the southeast borderland of the Tibetan Plateau.Journal of Geophysical Research,110:B11409．
Wang Q,Zhang P Z,Freymueller J T,Bilham R,Larson K M,Lai X A,You X Z,Niu Z J,Wu J C,Li Y X,Liu J N,Yang Z Q and Chen Q Z.2001． Present-day crustal deformation in China constrained by global position system measurements.Science,294(5542) :574-577．
Zhang P Z,Shen Z,Wang M,Gan W J,Burgmann R,Molnar P,Wang Q,Niu Z J,Sun J Z,Wu J C,Sun H R and You X Z.2004． Continuous deformation of the Tibetan Plateau from global positioning system data.Geology,32(9) :809-812．
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