Abstract:

Using the dispersion curves of Rayleigh waves that were extracted from the seismic noise of 53 broad-band stations
recorded in the Ordos Block and its southern Edge by two seismic stations cross correlation, we have obtained the average
dispersion curve of the Fen-Wei graben system, the Northern edge of Qinling, the Ordos Block and the Liupan Mountains, and
extracted the crustal and upper mantle structures of the four regions. The results show that the depth of the crust in the Fen-Wei
graben system, the northern edge of Qinling and the Ordos Block, and the Liupan Mountains is 34 km, ~40 km, and 49~50 km,
respectively. The velocity of S wave in the uppermost mantle of the corresponding region is 4.20 km/s, 4.25 km/s, 4.30 km/s, and
4.15 km/s. The most obvious difference of velocity structure appears in the upper crust. The Liupan Mountains has a low velocity
in the middle crust. The characteristics of velocity are almost the same for the lower crust.

Key words: ambient seismic noise, Green function, dispersion curve, crust and upper mantle velocity structure, Ordos block