Love Wave Tomography from Ambient Seismic Noise in North-China
详细信息
- 责任者：Fang Lihua (Institute of Geophysics ; China Earthquake Administration ; Beijing 100081 ; China) ; Wu Jianping
- 刊名：Chinese Journal of Geophysics
- 出版年：2013
- 卷期：56(7)
- 关键词：地震勘探 ; seismic exploration ; 层析技术 ; tomography ; 去噪 ; denoising ; 华北地区 ; North China
- 页码：p.2268-2279
- 图表：9 illus., 66 refs.
- 分类号：1600
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
We present the results of Love wave group velocity tomography in North China using ambient seismic noise observed at 200 portable seismic stations from North China Seismic Array.14-month continuous data have been cross-correlated to yield estimated empirical Love wave Green′s functions.5229 group velocity dispersion curves were measured by applying multiple filter method.Group velocity maps between 4 s and 30 s are reconstructed.Checkerboard tests indicate that the lateral resolution is estimated to be 0.25°×0.25° for most of the study area.The tomography maps at short periods agree well with the surface geological structure.North China basin and Shanxi rift are mapped as low velocity anomaly,while Yanshan uplift and Taihangshan uplift are mapped as high velocity anomaly.The tomography maps at intermediate periods outline the shapes of the basins and reveal the relative thickness of sedimentary cover.Dispersion curves show clear regional characteristics.The dispersion curves of Taihangshan uplift,Yanshan uplift and northeastern margin of Ordos block are consistent and are similar with those of typical craton.The dispersion curves of Zhang-Bo seismic zone are in agreement with Shanxi rift,and are close to Ethiopia rift.The dispersion curves of middle and western block are similar with other typical cratons.The dispersion curves of eastern block differ greatly with middle and western block and are lower than other cratons,which implies that the crust of eastern block suffers strong damage and alteration.The middle and western block are less affected by North China craton destruction and still keep the physical properties of stable craton.Great differences in topography,velocity structure,dispersion characteristics,crust thickness,lithosphere thickness and mantle transition zone thickness are observed between the western and eastern sides of Taihangshan gravity lineament.We infer the lineament is an important borderline to determine the destruction area of North China Craton and the destruction of North China craton is confined to the eastern part.