UC San Diego

In this dissertation, I use Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) to study the crustal deformation due to several recent large earthquakes around the Tibetan Plateau. The studied events include the 2005 Mw 7.6 Kashmir (Pakistan) earthquake that occurred in the northwest Himalaya, the 2015 Mw 7.8 Gorkha (Nepal) earthquake that occurred along central Himalaya, and the 2013 Mw 7.7 Balochistan earthquake that occurred in the Makran accretionary wedge in southwestern Pakistan. In particular, I focus on the observations and modeling of postseismic deformation due to these events. Despite of the challenging surface conditions for InSAR and GPS observations in the mountainous regions, I obtain robust measurements of postseismic deformation following the respective earthquake. Among all the three events studied in this dissertation, the observed postseismic displacements several years after the mainshock are all best explained by afterslip that primarily occurs at the downdip extension of the coseismic rupture. Viscoelastic relaxation and poroelastic relaxation seem to have played only a limited role in the postseismic relaxation of the respective earthquake during the corresponding observation period. Postseismic deformation following the 2005 Kashmir earthquake and the 2015 Gorkha earthquake seems to be inconsistent with models of a low viscosity channel beneath the Tibetan Plateau that are often advocated to explain the uplift and topography variations at the plateau margins. Results of this dissertation have implications for the mechanisms of the long-term growth of Tibetan Plateau and accommodation of plate convergence across the Himalayan Arc.