摘要
利用ISC报告以及中国和NEIC基本测震台网报告中的 80 974条P波初至到时资料(地震数为 70 5 3,台站数为 16 5 ,且地震和台站都分布在研究区内 ) ,对中国西南及邻区 (北纬10°～ 36°、东经 70°～ 110°)的深至 4 0 0km的上地幔三维速度结构进行了研究 ,分辨率达 2°×2° .初步结果表明 :①研究区速度的横向不均匀性 ,虽随深度增加而减弱 ,但至 4 0 0km深度时仍很明显 ;②在北纬 16°和 2 4°的纵剖面上 ,可以看到与印度板块向东和欧亚板块相碰撞挤压相对应的速度结构 ,以及印度板块与欧亚板块速度结构的差异 .在东经 90°的纵剖面上 ,与印度板块向北俯冲到欧亚板块 (青藏高原 )之下相对应的速度结构也比较明显 ;③在 90km深度的横剖面上 ,由缅甸的密支那至越南的洞海的低速条带 ,可能与红河断裂带有关 ;
D velocity structure of P wave in the upper mantle beneath southwestern China and its adjacent areas (10°N^36°N, 70°E^110°E) down to the depth of 400 km has been studied by using 80 974 first P-wave arrival times recorded at 165 stations from 7 053 events both within the studying areas, selected from the bulletins of ISC, China and NEIC. With a resolution of grid spacing of 2°×2°, the velocity heterogeneity on the horizontal profile is obvious though it attenuates with the depth increasing. In the vertical profiles of velocity along latitude 16°N and 24°N, the collision and extrusion of India plate to Eurasia plate is displayed, and a remarkable velocity difference from India plate to Eurasia plate is shown. In the vertical profile along longitude 90°E, the subducting of India plate northward beneath Eurasia plate (Tibet plateau) is also obvious. In the horizontal profile at the depth 90 km, a low velocity stripe from Myitkyina, Myanmar to Donghai, Vietnam seems to be related to Honghe fault belt. An illustration method of describing the resolution more directly and exactly has been proposed and utilized in this paper.
出处
《地震学报》
CSCD
北大核心
2002年第2期126-134,共9页
Acta Seismologica Sinica
基金
国家自然科学基金 (4 9734 15 0 )资助项目
关键词
中国西南
上地幔
三维速度结构
分辨率
P波
横向不均匀性
southwestern China and its adjacent areas
upper mantle
3-D velocity structure
description of the resolution
