Slip in the 2015 Mw 7.9 Gorkha and Mw 7.3 Kodari, Nepal, Earthquakes Revealed by Seismic and Geodetic Data: Delayed Slip in the Gorkha and Slip Deficit between the Two Earthquakes

We investigate the rupture process of the 25 April 2015 M-w 7.9 Gorkha, Nepal, earthquake and its biggest aftershock on 12 May 2015, based on joint inversion of teleseismic body waves, Interferometric Synthetic Aperture Radar, and Global Positioning System measurements. The Gorkha earthquake propagated unilaterally to the southeast along the Himalayan thrust fault (HTF), with coseismic slip separating into patches up-dip and down-dip of the hypocenter. Slip in the up-dip patch initially surrounded a region on the fault that did not slip. About 15 s after being surrounded, this region of the HTF then slipped, filling in the initial slip deficit. The delayed slip accounts for similar to 20% of the moment release in the Gorkha earthquake. The inferred coseismic slip in the Kodari earthquake is localized to one patch on the HTF, extending to the south and southeast from the hypocenter and 20-30 km to the northeast of the main slip patch in the Gorkha earthquake. The maximum coseismic slip in both the Gorkha and Kodari earthquakes is similar to 4.5 m. Online Material: Figures of waveform fits, predicted interferograms and surface displacement, and time-varying cumulative slip.