Rayleigh-wave Tomography Based on Ambient Seismic Noise in the Central and Western Blocks of the North China Craton

Using the one-year ambient noise records of 51 portable broadband stations across the Ordos Block and 138 permanent stations from May 2010 to April 2011 with data of the North China Array during the year of 2007,we obtained Rayleigh wave group velocity maps in the Central and Western Blocks of the North China Craton from 6s to 36s based on ambient seismic noise tomography.The results for 6s to 15s show the outline of tectonic units in the upper crust,such as rises and collapse basins;the results for 16s to 30s indicate the possibility of low-velocity zones within the middle and low crust of the Datong Basin and the western area of the Fenhe Basin;the results for 30 s to 36 s show that the thickness of the crust in the Eastern Block is thinner than that in the Central and Western Blocks,and the Moho depth of some collapse basins is respectively shallower compared with that of adjacent regions.