The Dynamics of the India-Asia collision revealed by Geodetic Imaging of the Tibetan plateau

Assessing the distribution of seismic hazard in the continents requires an understanding of how much deformation is accommodated by major faults. In one view, upper-crustal seismogenic faults respond passively to continuous viscous deformation of the underlying lithosphere; the alternative model is that lithospheric-scale faults control the distribution of deformation and hazard. We combine InSAR data derived from automatic (COMET-LiCSAR) processing of Sentinel-1 data (2015-2021) with a compilation of velocities from GNSS stations to produce the first high-resolution surface velocity field for the Tibetan plateau, where the collision of rigid Indian lithosphere with Eurasia has created the largest deforming region on the planet. We tie the reference frame of InSAR line-of-sight velocities to Eurasia using a joint inversion for surface velocities on a triangular mesh and reference frame adjustment parameters following the approach described in Wang and Wright 2012. We use the referenced InSAR data to invert for high-resolution East-West and Vertical velocities. The results show that the internal deformation of the Tibetan plateau can be described as a combination of distributed deformation and focused strain on a few major faults (Altyn Tagh, Kunlun, Haiyuan, Xianshuihe). We also observe continued postseismic transients associated with earthquakes that occurred within 20 years of the observations, including the 2001 Kokoxili and 1997 Manyi earthquakes. The highest elevations of the Tibetan plateau show dilatation, demonstrating the importance of internal buoyancy forces in continental tectonics. We present a new dynamic model that can explain the key features of the observations.