In response to the April 25, 2015 M7.8 Gorkha, Nepal Earthquake, the ARIA project is providing valuable information for the ongoing response to the April 25, 2015 M7.8 Gorkha earthquake in Nepal. The quake has caused significant regional damage and a humanitarian crisis.
Damage Proxy Map
The data products include a Damage Proxy Map, which covers the region around Kathmandu, was processed by the Advanced Rapid Imaging and Analysis (ARIA) team at JPL and Caltech using X-band interferometric synthetic aperture radar data from ASI's COSMO-SkyMed satellite constellation. The technique uses a prototype algorithm to rapidly detect surface changes caused by natural or human-produced damage. The assessment technique is most sensitive to destruction of the built environment. When the radar images areas with little to no destruction, its image pixels are transparent. Increased opacity of the radar image pixels reflects damage, with areas in red reflecting the heaviest damage to cities and towns. The color variations from yellow to red indicate increasingly more significant ground surface change. The time span of the data for the change is Nov. 24, 2014 to April 29, 2015. Each pixel in the damage proxy map is about 100 feet (30 meters) across.
The perspective image (above) shows the DPM overlaid on the terrain with the locations of damaged buildings identified by the National Geospatial-Intelligence Agency (NGA) preliminary damage assessment, indicated by the red and purple dots. As an example, the images on the side show how red regions in the DPM correlate with damaged buildings, as shown by the collapsed structures in the "after" image. The base map images were provided by Google. Before and after images were provided by DigitalGlobe.
Surface Deformation and Fault Slip Model
The ARIA team analyzed interferometric synthetic aperture radar images from the European Union’s Copernicus Sentinel-1A satellite, operated by the European Space Agency and also available from the Alaska Satellite Facility (https://www.asf.alaska.edu), to calculate a map of the deformation of Earth’s surface caused by the quake. This false-color map shows the amount of permanent surface movement caused almost entirely by the earthquake, as viewed by the satellite, during a 12-day interval between two Sentinel-1 images acquired on April 17 and April 29, 2015.
Links to ARIA Data Products and Images:
Damage Proxy Map (kmz): http://aria-share.jpl.nasa.gov/events/20150425-Nepal_EQ/DPM/ARIA_DPM_v0.5u_CSKd_20150430.kmz
GPS Coseismic Offsets (ascii file): http://aria-share.jpl.nasa.gov/events/20150425-Nepal_EQ/GPS/20150425Nepal_ARIA_Rapid_Offsets_v1.txt
GPS Coseismic Offsets (pdf): http://aria-share.jpl.nasa.gov/events/20150425-Nepal_EQ/GPS/20150425Nepal_ARIA_Rapid_Offsets_v1.pdf