Coseismic Vertical Displacement for a Shallow Thrust Earthquake From EarthDEM Data

Coseismic vertical displacements are important observations that help improve our understanding of fault mechanisms and how earthquakes alter landscapes. It has been a challenge to quantify long-wavelength topographic changes for thrust earthquakes using optical satellite imagery, as most recent studies focus on strike-slip earthquakes that produce highly localized, contrasting signals. Here we demonstrate the vertical displacements associated with the 25 April 2015 Gorkha, Nepal earthquake using EarthDEM digital elevation models derived from Maxar stereo-photogrammetric data. The DEM time series analysis shows that the earthquake caused the high Himalaya to subside for about 2.4 ± 1.7 m, about doubling the model-predicted subsidence of 1.2 ± 0.2 m. The large uncertainty of measured elevation changes, as well as their significant differences over different land covers shown in this study, highlight the need to correct vegetation bias in retrieving coseismic deformation from DEM data.