1995年永登地震黄土震陷变形特征及其形成机理  

DEFORMATION CHARACTERISTIC OF SEIDMIC SUBSIDENCE AND ITS FORMATION MECHANISM OF LOESS OF THE YONGDENG EARTHQUAKE IN 1995

作　　者：陈永明[1] 石玉成[2] 徐晖平[2] 刘红玫[2] 

机构地区：[1]中国科学技术大学地球和空间科学系,安徽合肥230026 [2]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《西北地震学报》2000年第4期465-470,475,共7页Northwestern Seismological Journal

基　　金：地震科学联合基金资助项目!(1990 44 );兰州地震研究所青年基金资助项目!(9913);中国地震局兰州地震研究所!论著编号 :LC2 0 0 0 0 5

摘　　要：通过对 1 995年永登地震形成的黄土震陷场地现场考察及震区震陷形成的地震动和黄土厚度条件 ,用震区震陷试验曲线计算了震区试验震陷量 .并通过震区震陷黄土和未震陷黄土微结构对比分析 ,探讨了黄土震陷形成的机理 .结果表明 ,震区试验计算的震陷量略小于实际地震震陷量 ;黄土震陷产生的机理为地震力剪切作用下孔隙结构破坏 ,在重力和压力作用下振动质密所致 .Firstly,the loess site of seismic subsidence of the Yongdeng earthquake in 1995 is investigated,and based on the PGA and the loess's thickness of the site,the value of loess seismic subsidence is calculated by using the relationship of σ d versus ε p of the earthquake site.Secondly,the formation mechamism of loessial seismic subsidence is studied by comparing the microtexture of undisturbed loess with the seismic subsided one.The result shows that the value of loessial seismic subsidence calculated using the test curve is smaller than the value of seismic subsidence caused by the earthquake.When exposed to dynamic stress,the void structure of loess will be destroyed by shear stress and become denser under the gravity force.This is the mechamism of loessial seismic subsidence.

关 键 词：黄土 震陷 微结构 变形机理 孔隙结构 剪切作用 

分 类 号：P315.9[天文地球—地震学] TU435[天文地球—固体地球物理学]