Surface wave tomography of China from ambient seismic noise correlation

We perform ambient noise tomography of China using data from the China National Seismic Network and surrounding global and regional stations. For most of the station pairs, we retrieve good Rayleigh waveforms from ambient noise correlations using 18 months of continuous data at all distance ranges across the entire region (over 5000 km) and for periods from 70 s down to about 8 s. We obtain Rayleigh wave group velocity dispersion measurements using a frequency-time analysis method and invert for Rayleigh wave group velocity maps for periods from 8 s to 60 s. The tomographic maps display significant features that correlate with surface geology. Major basins, including Tarim, Junggar, Qadaim, Sichuan, Bohai-Wan, and Songliao, are all well delineated by slow group velocities at shorter periods (10 to 20 s). The overall trend of crustal thickening from east to west is well represented by group velocity decreases from east to west at periods around 30 s.