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. Sufficient strain has accumulated over the past 5–7 centuries in the central seismic gap that could be released by two M_w 8.8 earthquakes.

KMS thank Professional Engineer and Scientist Exchange Program (PESEP) of ISRO and NASA for the support. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a Contract with the National Aeronautics and Space Administration (80NM0018D0004) and supported by NASA Earth Surface and Interior focus area and the NISAR project. KMS, MJ, and RA are supported by GAP project of SAC-ISRO. A portion of this work supports MJ’s PhD thesis. This work contains ALOS-2 SAR data from JAXA ALOS-2 satellite. Data products were provided under JAXA PI projects ALOS RA6 3278 and EO R3 A2N140. We thank, P. Jayaprasad, R. B. Upadhyaya, R. Sharma, and N. M. Desai for their support.