Vertical crustal movement around the southeastern Tibetan Plateau constrained by GPS and GRACE data

Abstract

Using measurements of continuous GPS stations and GRACE across the southeastern Tibetan Plateau, we found that the GRACE-derived vertical displacements are highly correlated with GPS-modeled vertical annual and semiannual displacements, which demonstrates that the vertical seasonal variations on ground surface are mainly caused by hydrological mass loading. After removing GRACE-modeled seasonal variations from the GPS time series, we used a stacking technique to filter out the common mode errors. Then we estimated the best noise model for the filtered time series, which can be best characterized by power law noise model. Finally, we determined the rates of vertical crustal movement of southeastern Tibetan Plateau. Our results suggest that the southeastern Tibetan Plateau is undergoing uplift, whereas the southern Sichuan–Yunnan fragment is subsiding with respect to the region to the north. The assumption of uniform extension throughout the crust does not explain the subsidence of southern Sichuan–Yunnan fragment.