地震地表破裂成因分析——以玉树地震为例  

Cause analysis of seismic wave- induced surface ruptures: a case study of Yushu Earthquake

作　　者：罗文行[1] 钱莉莉[1] 李德威[2] 李茂华[1] 

机构地区：[1]长江三峡勘测研究院有限公司(武汉),湖北武汉430074 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074

出　　处：《人民长江》2015年第15期69-73,共5页Yangtze River

基　　金：水利部国家大坝安全技术研究中心项目(2011NDS012);中国地质调查局项目"汶川地震区岩体稳定性评价技术方法"(1212010914036)

摘　　要：通过对玉树地震区4个典型地表破裂观察点地表破裂的观察分析,认为地表破裂可以分为同震地表破裂和震后受重力等影响而形成的滑坡后缘破裂以及河岸垮塌体破裂等。同震地表破裂大部分与发震断层的出露位置一致,是断层错动引起的,但有一部分地表破裂与断层位置并不重合,其形成可能另有原因。断层是地壳中相对软弱带,其消耗能量的作用大于传递能量的作用。这类同震地表破裂很可能是震源体破裂释放的能量以地震波的形式通过极不均匀的上地壳传播,再经过地壳中断层、裂隙、岩层岩性界面、褶皱面等复杂的折射、反射过程,在局部地段叠加增强后最终突出地表释放能量形成的。这种由于地震波突出地表形成地震破裂的过程,可以称之为地震地表破裂的波突成因。由于地震波携带有发震构造的相关信息,因此即使是波突成因的同震地表破裂,其组合形式也能够反映发震构造的一些基本特征。Revealed by field investigations on four typical surface rupture observation spots in Yushu Earthquake, the surface ruptures can be divided into the following types： the co-seismic surface ruptures and gravity-induced ruptures formed after earthquake, such as the rear edge rupture of the landslide body and the rupture of the collapsed body on the river bank etc. Most co-seismic surface ruptures are triggered by fault dislocation and thus occur in seismogenic zone, whereas some surface ruptures does not coincide with the fault formations and thus are probably caused by other factors. As the relatively weak zone of the earth crest, the faults do not play the role of transferring energy so much as dissipating energy. The energy released by seismic source rupture is transmitted in the form of seismic waves through rather heterogeneous upper crust, undergoing the complex refraction and reflection when going through the faults, fissures, rock interfaces and folded surfaces of the earth crest. Subsequently, the seismic waves are superimposed and amplified in some weak sections to the extent and they eventually breakthrough the earth sur-face and release energy to cause co-seismic surface rupture. The process in which the seismic waves break through the earth surface and cause seismic ruptures can be defined as the formation of seismic wave-induced surface ruptures. Since the seismic waves carry the related information of seismogenic structures, the configuration of the seismic wave-induced surface ruptures is indicative to the basic features of seismogenic structures.

关 键 词：地震地表破裂 地震波突出 成因分析 玉树地震 

分 类 号：P642[天文地球—工程地质学]