Determination of Crust Uplifting and Thickening of Qinghai-Tibetan Plateau from Time-Variable Gravity Measurements

The crustal uplift and thickening of Qinghai-Tibetan plateau was determined by the combined use of long-term absolute gravity measurements and GRACE satellite gravity measurement data. The results show that the obvious negative gravity change rate was detected by absolute gravity measurements. The systematic difference of the gravity change rates between absolute gravity measurements and GRACE measurements was also negative as 5 base stations at Dingxin, Delingha, Xining, Lhas, and Zhongba which representing the Alxa, Qilian and Lhas blocks were all in a crustal uplift status. The rising rate can be estimated numerically, and the velocity of Lhasa, Qilian and Alxa block is about 2.01±0.15 mm/a、1.88±0.19 mm/a and 1.91±0.10 mm/a, the crustal uplifting of the whole Qinghai-Tibetan plateau is about 1.94±0.17 mm/a, and the thickening is about 2.35±3.30 mm/a caused by the collision between the Indian and the Asianplates in the double-direction.