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. Editor's summary: The Tibetan Plateau is the roof of the world, but it also cracks and bends more than any other place. Wright et al. compiled thousands of satellite radar images of the plateau to make the highest-resolution view available of its deforming surface. Together with ground-based Global Navigation Satellite System (GNSS) data, the authors observed velocity patterns that tell the story of a continental collision and its northward pile-up and east-west collapse. The new details show that the region's collisional strain appears to be focused along a few particularly "weak" fault segments associated with old suture zones and contrasting rock strength. —Angela Hessler [ABSTRACT FROM AUTHOR]