【摘要】 本文利用华北地震科学台阵2007年1～4月份、190个宽频带和10个甚宽带垂直分量的地震噪声数据,通过互相关方法提取了瑞利面波的经验格林函数,用多重滤波方法测量了瑞利面波的群速度频散曲线.我们将研究区域划分为0.5°×0.5°的网格,利用噪声层析成像方法得到了研究区域7 s、12 s、16 s、23 s 的瑞利面波群速度分布图像,所得结果较好地揭示了地壳内部、尤其是浅部地壳的横向速度变化.研究表明,短周期的群速度分布同地表地质结构、地形密切相关;华北地区的地壳结构具有明显的横向不均匀性,华北盆地及山间的沉积盆地显示出低速异常,而基岩广泛出露的太行山和燕山隆起区,呈现高速异常;多数强震(M≥6.0级)都发生在高群速度与低群速度的过渡地带.更多还原

【Abstract】 We present the results of Rayleigh wave group velocity tomography in North China using ambient seismic noise observed at 190 broadband and 10 very broadband stations from North China Seismic Array.All available vertical component time-series for the 4 months span between Jan,2007 and Apr,2007 have been cross-correlated to yield estimated empirical Rayleigh wave Green’s functions.Group velocity dispersion curves were measured by applying multiple filter method.Group velocity maps withagrid spacing of 0.5°×0.5° at 7 s,12 s,16 s,and 23 s are reconstructed.The resulting ambient noise group velocity maps reveal the lateral velocity changes in the crust,especially in upper crust very well.Our results reveal an evident lateral heterogeneity of the curst in North China and demonstrate significant agreement with known geological and tectonic features at short periods.Orogenic belt and uplift areas,such as Yanshan uplift and Taihangshan uplift have high velocities,while depressions and sedimentary basins,such as North China basin,have low velocities.Most of the strong earthquakes(M≥6.0) occurred at the transition zones between high and low group velocities.更多还原