The Advanced Rapid Imaging and Analysis (ARIA) team at NASA's Jet Propulsion Laboratory in Pasadena, California, and Caltech, also in Pasadena, created this Damage Proxy Map (DPM) depicting areas in the southwestern part of Hokkaido, Japan, that are likely damaged as a result of the M6.6 September 5 earthquake in 2018 (shown by red and yellow pixels). The map is derived from synthetic aperture radar (SAR) images from the ALOS-2 satellites, operated by Japan Aerospace Exploration Agency (JAXA). The images were taken before and after the earthquake -- August 23 and September 6, respectively.

The map covers an area of 70 by 57 kilometers, shown by the large red polygon. Each pixel measures about 30 meters across. The color variation from yellow to red indicates increasingly more significant ground surface change. Preliminary validation was done by comparing with the high-resolution airborne optical imagery provided by the Geospatial Information Authority of Japan. This damage proxy map should be used as guidance to identify damaged areas, and may be less reliable over vegetated areas. For example, pixels over vegetated areas and farmlands may be false positives, and the lack of colored pixels over vegetated areas does not necessarily mean no damage.

The DPM was created by the NASA-JPL/Caltech ARIA team, and the ALOS-2 data were provided by JAXA. The algorithm development was carried out at JPL under a contract with NASA.

For more information about ARIA, visit http://aria.jpl.nasa.gov.