板内盆地地震构造分析——以江苏南部为例
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摘要
板内地震构造的主要控制因素是区域构造应力场和局部的特殊发震构造条件.本文提出江苏南部中强地震的主要构造标志是新生代活动盆地,盆地内的隐伏发震断层与区域构造应力场的最大主应力之间的夹角正好有利于剪切破裂的发生.三维有限元数值模拟证明,盆地形成过程中产生的地壳脆弱化,导致构造应力的重新分布和局部集中,盆地内部脆弱体中的隐伏断层是潜在的震源破裂面,盆地边缘积累的弹性应变能则是地震时释放的能量来源.
The main controlling factors of intraplate earthquakes are the regional tectonic stress field and the special conditions for the seismogenic structures. It is suggested that the most important indictors for the moderately strong earthquakes in southern Jiangsu province are the active basins of the Cenozoic era. The buried seismogenic faults within the basins are suitably oriented with respect to the maximum stress of the regional tectonic stress field which is favour of shear ruptures. Results of three dimensional numerical modeling by the finite element method demonstrate that the weakened zone of the crust in thebasins could give rise to redistribution and local accumulation of the tectonic stress. The buried faults re-lated to the zone of weakeness in the basins may be the potential sites of seismic ruptures. The elasticstrain energy built up near the edges of the basin can be the driving force for occurrence of earthquakes.
The main controlling factors of intraplate earthquakes are the regional tectonic stress field and the special conditions for the seismogenic structures. It is suggested that the most important indictors for the moderately strong earthquakes in southern Jiangsu province are the active basins of the Cenozoic era. The buried seismogenic faults within the basins are suitably oriented with respect to the maximum stress of the regional tectonic stress field which is favour of shear ruptures. Results of three dimensional numerical modeling by the finite element method demonstrate that the weakened zone of the crust in thebasins could give rise to redistribution and local accumulation of the tectonic stress. The buried faults re-lated to the zone of weakeness in the basins may be the potential sites of seismic ruptures. The elasticstrain energy built up near the edges of the basin can be the driving force for occurrence of earthquakes.
引文
[1]李起彤,南金生,苏顺昌.下扬子及部分邻区中强地震构造标志研究,地震学刊,1989,3:7—15
[2]马杏垣主编.中国岩石圈动力学纲要.1:400万中国及邻近海域岩石圈动力学说明书,北京:地质出版社,1987.
[3]叶洪,张文郁,于之水,夏勤.1979年溧阳6级地震震源构造的研究.地震地质,1980.2(4):27—48.
[4]胡连英,孙寿成.茅山断裂带结构和构造混杂岩带及磨砾岩之发现.地震学刊,1989.2:6—13.
[5]谢瑞征,等.江苏常熟—太仓5.1级地震发震构造条件.地震学刊,1990,4:67—69.
[6]Mekeown,F.A.,Investigations of the New Madrid earthguake region—overview and discussion,U.S.Geoioglcal Survey Professional Paper,1236—A,1982.
[7]Talwani,P.and Rajendran,k.,Some seismological and geometric features of intraplate earthquakes,Tectonophysics,186,19—41,1991.
[8]笠原庆—·地震力学·赵仲和等译·北京:地震出版社,1984.
[9]Tonston,A.C.and kanter,A.R.,Earthguakes in stable continental crust,Scientific American,262(3),68—75,1990.
[2]马杏垣主编.中国岩石圈动力学纲要.1:400万中国及邻近海域岩石圈动力学说明书,北京:地质出版社,1987.
[3]叶洪,张文郁,于之水,夏勤.1979年溧阳6级地震震源构造的研究.地震地质,1980.2(4):27—48.
[4]胡连英,孙寿成.茅山断裂带结构和构造混杂岩带及磨砾岩之发现.地震学刊,1989.2:6—13.
[5]谢瑞征,等.江苏常熟—太仓5.1级地震发震构造条件.地震学刊,1990,4:67—69.
[6]Mekeown,F.A.,Investigations of the New Madrid earthguake region—overview and discussion,U.S.Geoioglcal Survey Professional Paper,1236—A,1982.
[7]Talwani,P.and Rajendran,k.,Some seismological and geometric features of intraplate earthquakes,Tectonophysics,186,19—41,1991.
[8]笠原庆—·地震力学·赵仲和等译·北京:地震出版社,1984.
[9]Tonston,A.C.and kanter,A.R.,Earthguakes in stable continental crust,Scientific American,262(3),68—75,1990.
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