西北地震学报2012，Vol.34Issue(3)：224-233,313,316,12.DOI:10.3969/j.issn.1000-0844.2012.03.0224
青藏高原东北缘地壳上地幔速度结构的地震层析成像研究
Seismic Tomography of the Velocity Structure of the Crust and Upper Mantle in Northeastern Margin of the Qinghai-Tibet Plateau
摘要
Abstract
The seismic data including 3 229 local earthquakes (Ms≧1. 5) and 168 teleseismic events occurred during 1980 to 2002 recorded by 130 seismic stations in the seismic networks of Gansu, Qinghai, Ningxia and Sichuan province are collected, and from 55 024 local phases we selecte 51 210 with the maximum travel time residual of 3. 0 s, and 2 651 teleseismic phases. The tomographic inversion results show that; (1) Lower P-wave velocity anomaly exists widely in the lower crust beneath the northeastern margin of the Qinghai - Tibet plateau. Average P-wave velocity in most of the top of upper mantle is 8. 05 km/s that is close to the global continental average Pn-wave velocity with 8. 1 km/s. It indicates the existence of a clear Moho interface and strong reflections from Moho interface. (2) The epicenters of most strong earthquakes occurred in the research region are located in the lower velocity areas in the 10 km depth range, around the higher velocity areas in the 30 km depth range and lower velocity areas in the 50 km depth range, which suggests that these areas could be the possible earthquake pregnancy regions. (3) Major fault belts in the region are reverse thrust with strike slip, locate on the transition zones between lower and higher velocity anomalies, and are possibly ultra-crustal faults. (4) The arc belt from Zhangye to Haiyuan and Pingliang and turns to south is possibly the marginal belt of Qinghai -Tibetan plateau, and indicates the platform activation in Alashan platform. (5) The 2D velocity perturbation profile taken from the seismic tomographic results shows fairly agreement with deep seismic sounding profile.关键词
青藏高原东北缘/地震层析成像/莫霍面/地壳上地幔速度结构Key words
Northeastern margin of the Qinghai-Tibetan plateau/Seismic tomography/Moho inter-face /Velocity structure of crust and upper mantle分类
天文与地球科学引用本文复制引用
周民都,王椿镛,曾融生..青藏高原东北缘地壳上地幔速度结构的地震层析成像研究[J].西北地震学报,2012,34(3):224-233,313,316,12.基金项目
国家自然科学基金重点项目(40334041) （40334041）
国家重点基础研究发展规划项目(95-13-02-02,95-13-02-03) （95-13-02-02,95-13-02-03）
甘肃省自然科学基金(ZS981-A25-011-Z) （ZS981-A25-011-Z）
中国地震局地震预测研究所基本科研业务费(A68-4) （A68-4）
中国地震局兰州地震研究所论著编号:LC2012015 （）
