摘要
中国大陆东部及海域 ( 98°～ 1 5 0°E,5°～ 5 0°N)位于欧亚大陆和太平洋两大板块的衔接地带 ,且深受来自印度洋板块活动的影响 .本文利用该区域内的 35个数字地震台记录的面波资料 ,采取多重滤波技术等时频分析方法 ,求得了 1 2 5 2条路径上基阶瑞利波的频散曲线 ,然后将研究区域划分为 1°× 1°的网格 ,通过 Occam反演方法求得了 1 0～ 1 5 8s周期范围内基阶瑞利波群速度在研究区域内的分布 .这些速度分布大致反映了不同深度范围介质 S波速度的横向变化情况 .利用求得的纯路径频散 ,进一步反演得到了青藏高原东部—太平洋、南海—蒙古两个剖面的 S波速度随深度的变化 ,发现研究区内的横向不均匀性直到 40 0 km仍很明显 。
Eastern China and vicinal sea areas(98°～150°E, 5°～50°N)are located i n the junction zone of Eurasian and Pacific plates, and it is also profoundly in flue nced by the collision between India and Eurasian plates. We utilized surface wa ve data recorded by digital seismic stations in the area, extracted dispersion c urves of fundamental-mode Rayleigh waves along 1 252 paths by means of tim e-frequ ency analysis based on multiple-filter and other techniques. The study area was divided into grids with 1°×1°, group velocity distributions of fundamental R aylei gh waves between 10～158 s were determined by Occam′s inversion. These veloci ty distributions roughly depict the lateral variations of shear wave velocities in different depth ranges. With the determined pure path dispersions we further inv erted for the S wave velocity structures along two profiles from eastern Tibet t o Pacific Ocean and from South China Sea to Mongolia. It is found that the later al heterogeneity is obvious down to 400 km depth, and the velocity structures ar e correlated with tectonic units in the study area.
出处
《地震学报》
CSCD
北大核心
2001年第5期471-479,共9页
Acta Seismologica Sinica
基金
国家高科技发展项目 (82 0 0 1 0 4 )
自然科学基金项目 (4 9874 0 0 8)
