The Nepal earthquake that hit just before noon on Saturday, April 26, 2015 officially has a name: it’s the Gorkha earthquake. The sudden slip of the tectonic plates during the earthquake literally reshaped the land. In a continent-continent collision like this one, the area closest to the fault rupture is uplifted, while the previously-buckled plate interior slaps flat, subsiding in the release of stress.
Uplift [blue] and subsidence [yellow] from the M7.8 earthquake in Nepal. Image credit: DLR/EOC
The European Space Agency’s Sentinel-1A satellite tracked both uplift [blue] and subsidence [yellow], recording elevation changes of up to 1 meter, and a horizontal north-south shift of up to 2 meters.
Interferogram identifying areas of change between measurements before and after the Gorka earthquake. Image credit: Copernicus data/ESA/Norut/PPO.labs/COMET–ESA SEOM INSARAP
They’ve used the same data to create interferograms of how the region has changed in consecutive measurements before and after the earthquake. Each coloured fringe represents about 10 centimeters of displacement. Overall, Kathmandu is little taller and Mount Everest is a tiny bit shorter than it was a month ago.
Poor weather not only made things a little bit more miserable on the ground, but also limited the utility of fly-overs from NASA’s satellite network.
Cloudy skies have limited the ability of NASA’s satellite network to provide meaningful data for damage assessment. Image credit: NASA
In related news, as part of efforts to increase access to hazard mitigation and risk reduction research, the Seismological Society of America has temporarily opened access to their collection of articles on tectonics, structure, and earthquake history of the Himalayas.