Early post-seismic deformation due to the 2015 M7.8 Gorkha (Nepal) earthquake: Constraints on rheology of the Tibetan lithosphere

Abstract:

Over the last decade several major earthquakes have occurred on faults
bounding the Tibetan plateau, including the 2005 M7.6 Kashmir
(Pakistan), the 2008 M7.8 Wenchuan (China), and the 2015 M7.8 Gorkha
(Nepal) earthquakes. Time-dependent surface deformation following
these earthquakes provides important constraints on the effective
rheology of the lower crust and upper mantle beneath Tibet. The
epicentral area of the 2015 Gorkha (Nepal) earthquake has been
exceptionally well imaged by several Interferometric Synthetic
Aperture Radar (InSAR) satellites including ALOS-2 (Japanese Space
Agency) and Sentinel-1 (European Space Agency) missions. We will
present observations of surface deformation in the early (several
months) postseismic period following the 2015 Gorkha earthquake, and
compare surface deformation data to numerical models of postseismic
transients assuming various relaxation mechanisms. We will also
compare the postseismic deformation data from different earthquakes at
the boundaries of the Tibetan Plateau to evaluate the effects of
lateral heterogeneities in rheological properties of the ductile
substrate.