从深部构造特征看布瑞兹曼效应对强震的引发作用
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摘要
根据中国地震局地球物理勘探中心的深部探测成果,发现许多大地震的震源位于上地幔隆起区的边缘。由于深部物质的上涌作用,隆起区的莫霍面往往不再是一个尖锐的间断面,而是一个具有一定厚度的、非常复杂的过渡带。可以想象,深部上隆作用势必会对其边缘的断层产生重要的影响。从布瑞兹曼效应的角度出发对这一问题进行了初步的探讨。由于断层两盘的相对旋转运动可通过追逐让位来实现,不存在断层两端的让位问题,因此,相对而言,断层的旋转性滑动更容易发生,而旋转滑动可破坏断层接触面上的凸凹不平体,使接触面变得更加平滑,有利于以后的剪切错动。
In the light of the results of deep exploration by Geophysical Exploration Center,CEA,it can be found that many strong earthquake focuses locate at the margin of upper mantle uplifts,and the Moho in an uplift region is no longer a sharp discontinuity,but a very complicated transitional zone due to the upsurging of deep substances.It is certain that the upsurging action must have a considerable effect on the faults nearby.A preliminary study is made from viewpoint of Bridgman effect.A relative rotation slip of two walls of a fault can be realized through chase-style motion,and no pre-left space is necessary at the two ends of the fault.Thus,the relative rotation will be much easier to take place than shear faulting.Due to the rotational movement caused by the uplifting action,the barriers existing on the contact surface of two walls will be destroyed and the contact surface will become smoother.It paves the way for future shear faulting.
In the light of the results of deep exploration by Geophysical Exploration Center,CEA,it can be found that many strong earthquake focuses locate at the margin of upper mantle uplifts,and the Moho in an uplift region is no longer a sharp discontinuity,but a very complicated transitional zone due to the upsurging of deep substances.It is certain that the upsurging action must have a considerable effect on the faults nearby.A preliminary study is made from viewpoint of Bridgman effect.A relative rotation slip of two walls of a fault can be realized through chase-style motion,and no pre-left space is necessary at the two ends of the fault.Thus,the relative rotation will be much easier to take place than shear faulting.Due to the rotational movement caused by the uplifting action,the barriers existing on the contact surface of two walls will be destroyed and the contact surface will become smoother.It paves the way for future shear faulting.
引文
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2郭安宁,陈家超,中国大震问题[M].北京:地震出版社,2002.2Guo Anning and Chen Jiacao.On the big earthquakes in China[M].Beijing:Seismological Press,2002.(in Chi-nese)
3郭增建.地旋与地震预报[J].西北地震学报,1988,1:82-85.3Guo Zengjian.Geo-rotation and earthquake forecasting[J].Northwestern Seismological Journal,1988,1:82-85.(in Chinese)
4郭增建,秦保燕.震源物理[M].北京:地震出版社,1979.4Guo Zengjian and Qin Baoyan.Seismic source physics[M].Beijing:Seismological Press,1979.(in Chinese)
5国家地震局《一九七六年唐山地震》编辑组.一九七六年唐山地震[M].北京:地震出版社,1982.5Compiling Group of1976Tangshan Earthquake,CEA.1976Tangshan Earthquake[M].Beijing:Seismological Press,1982.(in Chinese)
6李松林,等.玛沁-兰州-靖边地震测深剖面地壳速度结构的初步研究[J].地球物理学报,2002,45(2):210-217.6Li Songlin,et al.A preliminary study on crustal velocity structures of Maqin-Lanzhou-Jingbian deep seismic sounding profile[J].Chinese J.Geophys,2002,45(2):210-217.(in Chinese)
7李松林,等.海原8.5级大震区地壳结构探测研究[J].中国地震,2001,17(1):16-23.7Li Songlin,et al.Study on crustal structure of Haiyuan strong earthquake region[J].Earthquake Research in Chi-na,2001,17(1):16-23.(in Chinese)
8刘昌铨,嘉世旭.唐山地震区地壳上地幔结构特征[J].地震学报,1986,8(4):341-352.8Liu Changquan and Jia Shixu.Structural property of the crust and the upper mantle in the Tangshan earthquake re-gion[J].Acta Seismologica Sinica,1986,8(4):341-352.(in Chinese)
9任青芳,等.菏泽地区地壳结构特征与地震[J].华北地震科学,1992,10(3):45-52.9Ren Qingfang,et al.Characteristics of crustal structures in Heze Region and earthquakes[J].North China Earthquake Sciences,1992,10(3):45-52.(in Chinese)
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