玉树震区及邻近地区壳幔速度结构特征  

A STUDY OF THE CRUST-MANTLE VELOCITY STRUCTURE BENEATH THE YUSHU EARTHQUAKE ZONE AND ITS ADJACENT AREAS

作　　者：张建狮[1] 王夫运[1] 刘宝峰[1] 王帅军[1] 赵金仁[1] 张成科[1] 李怡青[1] 刘巧霞[1] 刘兰[1] 

机构地区：[1]中国地震局地球物理勘探中心,郑州450002

出　　处：《地震地质》2014年第2期322-332,共11页Seismology and Geology

基　　金：青海玉树7.1级地震科学考察项目;国家自然科学基金(90814012);地震科技星火计划青年基金项目(XH12067Y)共同资助

摘　　要：对获得的玉树震区的人工地震测深资料,利用正演拟合地震测深方法进行处理与计算,获得了玉树震区的地壳速度结构和构造的基本特征.结果表明,不同区域的地壳速度结构在纵向和横向上均具有明显的非均匀性.地壳呈层状结构,研究区结晶基底界面起伏较大,玉树附近下方较厚达8km左右,在400.0km桩号向北至温泉方向基底结构逐渐减薄为2.5km.基底界面的凹陷、隆起与不同的地质构造单元具有较好的对应关系;地壳厚度由囊谦、玉树附近的72km向南、北逐渐减薄为62km.在200.0 ～ 400.0km桩号之间二维速度等值线及壳内界面起伏变化较大,在玉树附近下方莫霍面有一弧形凹陷.In this paper the crustal velocity structure is obtained along Yushu earthquake zone, using wide angle reflection and refraction data. The results reveal strong vertical and lateral heterogeneities in the crust, as well as the basic characteristics of the crustal velocity structure and the tectonics along the seismic sounding profile. Results show that crustal velocity structure is featured with significant regional heterogeneity both in the longitudinal and lateral directions. The crust is of layered structure, and the crystalline basement interface undulates greatly beneath the study area, which is about 8km in thickness beneath Yushu and gradually thins northwards to 2.5km beneath the Stake 400.0km at Wenquan. There are good correlations of the depressions and uplifts on basement interface with different tectonic units. The crust gradually thins towards both south and north direction to a thickness of 62km from 72kin beneath Nangqian and Yushu. There exist big undulations in 2D velocity contours and the interfaces in the crust between Stakes 200.0 - 400.0km, and there is presence of an arcshaped depression in the Moho beneath the Yushu area.

关 键 词：地震测深 速度结构 断裂 玉树地震 

分 类 号：P315.63[天文地球—地震学]