Geodetic insights to the Himalayan megathrust kinematics unravel increased earthquake hazard

Measurements of both horizontal and vertical surface displacements allow for rigorous estimation of the moment deficit and the fault locking along subduction zones, including continental megathrusts. Previous measurements in the Himalayas were restricted to horizontal velocities from Global Navigational Satellite Systems, so the locking and the width of transition from apparent locking to interseismic creep were not well constrained. We present new observations of surface deformation from interferometric synthetic aperture radar for approximately 800 km along Himalaya. The interseismic velocity field along arc-perpendicular transects suggests a 5-8 mm/yr uplift in the higher Himalayas. We infer that the megathrust accommodates 20-22 mm/yr convergence over a width of ~115 km from the frontal thrust followed by a ~40 km transition zone. With an inferred seismic potency rate of ~2600 m³/yr, the strain accumulated over five to seven centuries in the central seismic gap could be released by two Mw 8.8 earthquakes.