Days after a 6.4-magnitude earthquake rocked Puerto Rico, followed by hundreds of aftershocks, the full extent of damage is only beginning to be realized.

NASA scientists are using satellite data to help federal and local agencies identify areas with potential damage. Earthquakes cause permanent changes to the ground surface. By comparing interferometric synthetic aperture radar (InSAR) data acquired on Jan. 9, 2020, with data acquired on Dec. 28, 2019, from the Copernicus Sentinel-1A satellite, the scientists were able to map where, how much and in what direction those changes occurred.

Managed by the European Space Agency (ESA), the Copernicus Sentinel-1A satellite was able to see the eastern two-thirds of the island during the Jan. 9 flyover. On the map, red indicates areas where the ground was changed, or displaced, with darker shades corresponding to more significant displacement. The scientists found that the greatest displacement from the flyover area occurred west of the city of Ponce (identified by the green star), not far from the quake's offshore epicenter. They recorded up to 5.5 inches (14 centimeters) of ground change there. The ground appeared to shift downward and slightly to the west.

The quake epicenter and the cluster of quakes and aftershocks in the region identified by the United States Geological Survey (shown as orange circles) fall just west of the satellite's Jan. 9 track. Because of this, scientists also plan to analyze data from Sentinel-1A's forthcoming Jan. 14 flyover, which will include western Puerto Rico.

The NASA Earth Applied Sciences Disasters Program has activated Tier 1 response in support of this disaster and is in contact with the Federal Emergency Management Agency, the United States Geological Survey and Health and Human Services (HHS) to provide NASA Earth-observing data in support of response and recovery efforts. Products in the process of being produced include Suomi-NPP-based "Black Marble" power outage maps, damage maps, and landslide maps. A webpage has also been created on the NASA Disasters Mapping Portal to supply relevant GIS data products.

The map contains modified Copernicus Sentinel data processed by ESA and analyzed by scientists at NASA's Jet Propulsion Laboratory, and earthquake location data from the USGS.

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Arielle SamuelsonJet Propulsion Laboratory, Pasadena, Calif.818-354-0307arielle.a.samuelson@jpl.nasa.govWritten by Esprit Smith, NASA's Earth Science News team2020-006