玉树震区及邻近地区壳幔速度结构特征

doi:10.3969/j.issn.0253-4967.2014.02.004

摘要/Abstract

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。

关键词: 地震测深, 速度结构, 断裂, 玉树地震

Abstract: 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 8 km in thickness beneath Yushu and gradually thins northwards to 2.5 km beneath the Stake 400.0 km 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 62 km from 72 km 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 arc-shaped depression in the Moho beneath the Yushu area.

Key words: seismic sounding, velocity structure, fault, Yushu earthquake

中图分类号:

P315.63

张建狮, 王夫运, 刘宝峰, 王帅军, 赵金仁, 张成科, 李怡青, 刘巧霞, 刘兰. 玉树震区及邻近地区壳幔速度结构特征[J]. 地震地质, 2014, 36(2): 322-332.

ZHANG Jian-shi, WANG Fu-yun, LIU Bao-feng, WANG Shuai-jun, ZHAO Jin-ren, ZHANG Cheng-ke, LI Yi-qing, LIU Qiao-xia, LIU Lan. A STUDY OF THE CRUST-MANTLE VELOCITY STRUCTURE BENEATH THE YUSHU EARTHQUAKE ZONE AND ITS ADJACENT AREAS[J]. SEISMOLOGY AND GEOLOGY, 2014, 36(2): 322-332.

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