Crustal and uppermost mantle velocity structure beneath the central-eastern Tibetan Plateau from P-wave tomography

Based on joint inversion with 14 484 P-wave （Pg and Pn） first arrival times, we obtained regional 3-D P velocity structure beneath the central-eastern Tibetan Plateau, including crustal P velocity, uppermost mantle P （Pn） velocity, and Moho depth. The results show that the crustal P velocity ranges from 5.2 to 7.2 km/s, the Pn velocity ranges from 7.7 to 8.4 km/s, and the crustal thickness ranges from 48.0 to 68.6 km. The crustal and uppermost mantle structure is strongly heterogeneous, which generally correlates with geologic blocks. The crustal P velocity structure shows that prominent low velocity zones exist in the middle and lower crust. There are great difference in the distribution of high and low velocity anomalies between upper crust and mid-lower crust. High velocity anomalies primarily exist in the upper crust of the Qiangtang block and the Baryan Har block, while become lower as depth increases. The Qaidam basin shows low velocity anomaly in the upper crust while high in the lower crust. High Pn velocity exists in the Qaidam basin and the Lhasa block with a maximum velocity of about 8.4 km/s, while the Baryan Har block and the Qiangtang block mainly show low Pn velocity anomalies, which reach as low as 7.7 km/s. Crustal thickness is mainly characterized by thick in the south and thin in the north. The crust is thicker in the eastern Qiangtang block and the Lhasa block, while thinner in the Qaidam basin, the eastern Baryan Har block and the western part of the Qiangtang block, which shows the characteristics of lithospheric deformation due to the northward subduction from the Indian Plate to the Eurasian Plate.