3‐D Tomography for the S‐Wave Quality Factor of the Crust and Upper Mantle Beneath the Chinese Mainland

We select 223 pairs of Rayleigh wave from 2681 waveforms recorded at 58 stations in the Eurasia continent and west Pacific region. These data are two‐path records of the rays which pass through the Chinese mainland and meet the requirements of our study. Using the method combining phase‐matched filter and Winner filter in frequency domain, we calculate the attenuation coefficient of the mixed path between two stations. We make a mesh of 4° x 4° to the Chinese mainland and invert the attenuation coefficient of pure path for each grid element. Then we perform depth inversion for each element based on the velocity and density models to obtain the S wave quality factor (Qβ) in the depth range of about 10~350km. In this way the Qβ distribution of the whole Chinese mainland is acquired. The result shows that the lateral and vertical change of the Qβ distribution is very evident. The asthenosphere structure can be clearly identified from the image. The Qβ structure manifests remarkable variations between tectonic units. This result provides helpful information for the study on the material property, viscidity structure, and dynamic process of the Earth interior beneath the Chinese mainland.