汶川8.0级地震构造动力成因分析
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摘要
汶川8.0级地震发生在青藏活动地块区的东部边界带,是继2001年昆仑山口西大地震之后青藏块区的又一次巨大地震。根据龙门山推覆逆冲断裂带深浅部构造背景和壳幔结构特征,文中构建了汶川地震的震源简化模型。并依据震源模型的力学抽象建立了孕震过程的动力学方程组,且在简化解释下给出了孕震过程中的应力、应变的解析表达式。应用模型的解析解,并参照龙门山构造区的构造形变观测结果,初步讨论了汶川地震的孕震过程,给出了汶川8.0级地震的孕育过程可达3000多年的结果,指出由于龙门山地区构造形变速率很低,因而导致孕震过程缓慢,大震复发期较长的基本结果。
The 2008 Wenchuan 8.0 earthquake occurred on the eastern boundary of the active Tibet block,and is another strong earthquake in the Tibet block after the 2001 Kunlun 8.1 earthquake.Based on the characters of the structure of crust and mantle and the deep or shallow geological background in the Longmenshan dip fault,this paper constructs a simplified source model of the Wenchuan earthquake,from which dynamic equations from this model are constructed and analytic expressions of stress and strain in the progress of seismogeny are derived.Referring to the geological deformation in the Longmenshan region,we further discuss the process of the Wenchuan earthquake by the analytic solution of the model.The result shows that the process of seismogeny may endure about 3200 years and is very slow and longer because of the lower geological deformation in the Longmenshan region.
The 2008 Wenchuan 8.0 earthquake occurred on the eastern boundary of the active Tibet block,and is another strong earthquake in the Tibet block after the 2001 Kunlun 8.1 earthquake.Based on the characters of the structure of crust and mantle and the deep or shallow geological background in the Longmenshan dip fault,this paper constructs a simplified source model of the Wenchuan earthquake,from which dynamic equations from this model are constructed and analytic expressions of stress and strain in the progress of seismogeny are derived.Referring to the geological deformation in the Longmenshan region,we further discuss the process of the Wenchuan earthquake by the analytic solution of the model.The result shows that the process of seismogeny may endure about 3200 years and is very slow and longer because of the lower geological deformation in the Longmenshan region.
引文
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[16]梅世蓉.1976年唐山地震[M].北京:地震出版社,1982.
[2]张国民,马宏生,王辉,等.中国大陆活动地块与强震活动关系[J].中国科学(D辑),2004,34(7):591-599.
[3]张国民,马宏生,王辉,等.中国大陆活动地块边界带与强震活动[J].地球物理学报,2005,48(3):602-610.
[4]张国民,尹京苑.强震孕育中短期物理基础研究[M].北京:地震出版社,2001.
[5]郭增建,马宗晋.中国特大地震研究(一)[M].北京:地震出版社,1988.
[6]刘桂萍,傅征祥.海原大地震对古浪大地震的静应力触发研究[J].地球物理学报,2001,44(z1):107-115.
[7]西藏自治区科学技术委员会,国家地震局科技监测司.西藏察隅当雄大地震[M].拉萨:西藏人民出版社,1988.
[8]张国民,田勤俭,王辉.可可西里-东昆仑地震带强震活动[J].地学前缘,2003,10(1):20-28.
[9]Tapponnier P,Molnar P.Activity faulting and tectonics in China[J].J Geophys Res,1977,82:2 905-2 930.
[10]邓起东,陈社发,赵小麟.龙门山及其邻区的构造和地震活动及动力学[J].地震地质,1994,16(4):389-403.
[11]张培震.中国地震灾害与防震减灾[J].地震地质,2008,30(3):577-583.
[12]徐锡伟,闻学泽,叶建青,等.汶川8.0级地震地表破裂带及其发震构造[J].地震地质,2008,30(3):597-629.
[13]刘启元,陈九辉,李顺成,等.汶川8.0级地震:川西流动地震台阵观测数据的初步分析[J].地震地质,2008,30(3):584-596.
[14]朱艾斓,徐锡伟,郑荣章,等.汶川8.0级地震部分余震重新定位及地震构造初步分析[J].地震地质,2008,30(3):759-767.
[15]陈学忠,李艳娥,郭祥云.2008年5月12日四川汶川8.0级地震前后震源区应力水平估计[J].国际地震动态,2008,6:1-3.
[16]梅世蓉.1976年唐山地震[M].北京:地震出版社,1982.
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