Crust and upper mantle structure in east China and sea areas

• 作 者: 李红谊 黄忠贤
• 出 处: Acta Seismologica Sinica
• 发表日期: 2004年期
• 关键词: mantle crust Yangtze plateau trough continental Rayleigh tectonic oceanic invers

Eastern China and vicinal sea areas (98~150E, 5~50N) are located in the junction zone of Eurasian and Pacific plates, and it is also profoundly influenced by the collision between Indian and Eurasian plates. We utilized surface wave data recorded by 35 digital seismic stations in the area, extracted dispersion curves of fundamental-mode Rayleigh waves along 1 252 paths by means of time-frequency analysis based on multiple-filter and other tech-niques. The study area was divided into a grid of 11, group velocity distributions of fundamental Rayleigh waves between 10~158 s were determined by Occams inversion. These velocity distributions roughly depict the lateral variations of shear wave velocities in different depth ranges. With the determined pure path dispersions we further inverted for the S wave velocity structures along two profiles from eastern Tibet to Pacific Ocean and from South China Sea to Mongolia. It is found that the lateral heterogeneity is obvious down to 400 km depth, and the velocity structures are correlated with tectonic units in the study area.

Eastern China and vicinal sea areas (98-150E, 5-50N) are located in the junction zone of Eurasian and Pacific plates, and it is also profoundly influenced by the collision between Indian and Eurasian plates. We utilized surface wave data recorded by 35 digital seismic stations in the area, extracted dispersion curves of fundamental-mode Rayleigh waves along 1 252 paths by means of time-frequency analysis based on multiple-filter and other tech-niques. The study area was divided into a grid of 11, group velocity distributions of fundamental Rayleigh waves between 10 ~ 158 s were determined by Occams inversion. These velocity distributions roughly depict the lateral variations of shear wave velocities in different depth ranges. With the determined pure path dispersions we further inverted for the S wave velocity structures along two profiles from eastern Tibet to Pacific Ocean and from South China Sea to Mongolia. It is found that the lateral heterogeneity is obvious down to 400 km depth, and the velocity structures are correlated with tectonic units in the study area.