High-resolution geodetic velocities reveal role of weak faults in deformation of Tibetan Plateau

Understanding the key mechanisms that control the tectonic deformation of the continents remains a fundamental challenge in geodynamics. We present a high-resolution geodetic velocity field of the Tibetan Plateau, which shows that a few major strike-slip fault systems separate regions of more uniformly distributed deformation. We suggest that focused strain on major fault systems is enabled by relatively low-viscosity ductile shear zones extending through the lithosphere beneath the seismically active fault planes. Simple model calculations show that high slip rates on the Kunlun Fault enable east-west extension to be distributed broadly across the relatively weak southern and central Tibetan Plateau. Activation of the Kunlun fault in the Miocene at the same time as the onset of rifting in the north-south grabens suggests a causal relationship.