Jin Fang, Greg Houseman, Tim J Wright , Lynn Evans, Timothy J Craig, John Elliott, Andy Hooper 

The dynamics of lithospheric deformation in the India-Eurasia collision zone has been debated over many decades. Here we test a two-dimensional (2-D) Thin Viscous Shell (TVS) approach that has been adapted to explicitly account for displacement on major faults and investigate the impact of lateral variations in depth-averaged lithospheric strength. We present a suite of dynamic models to explain the key features from new high-resolution Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) as well as Global Navigation Satellite System (GNSS) velocities. Comparisons between calculated and geodetically observed velocity and strain rate fields indicate: (a) internal buoyancy forces from Gravitational Potential Energy (GPE) acting on a relatively weak region of highest topography (>2,000 m) contribute to dilatation of the high plateau and contraction on the margins; (b) a weak central Tibetan Plateau ~10^21 Pa s compared to far-field depth-averaged effective viscosity of 10^22 to 10^23 Pa s) is required to explain the observed long-wavelength eastward velocity variation away from major faults; (c) resisted slip on faults produces strain localization and clockwise rotation around the Eastern Himalayan Syntaxis (EHS). We discuss the tectonic implications for the rheology of the lithosphere, distribution of geodetic strain, and partitioning of active faulting and seismicity.