Another earthquake hit Mexico early Saturday morning. The 6.2 quake comes just days after a devastating 7.1 magnitude earthquake shook central Mexico on Tuesday, claiming the lives of at least 295 people and destroying at least 3,000 buildings in the city’s capital. Authorities are continuing to search for trapped survivors, but due to the extensive damage and rubble, these efforts are often very difficult. In order to help Mexican authorities respond effectively, NASA produced satellite-imagery maps showing the damage.
Scientists at The California Institute of Technology and NASA’s Jet Propulsion Lab used before-and-after images to create what’s called a ‘damage proxy map,’ displaying areas of central Mexico, including Mexico City.
The before images were taken on Sept.8, less than two weeks before the quake hit, whereas the after images were taken on Sept. 20, just hours after the earthquake. The photos were taken by two radar tools operated by the European Space Agency: Copernicus Sentinel-1A and Sentinel 1-B satellites. The information was then processed by Advanced Rapid Imaging and Analysis (ARIA), a NASA-funded project, that works to produce data to support communities across the globe.
“ARIA data products can provide rapid assessments of the geographic region affected by a disaster, as well as detailed imaging of locations where damage occurred. Radar can 'see' through clouds day and night and measure centimeter-level ground movements,” according to a statement from NASA.
The images were immediately given to Mexican authorities on the day of the quake.
“The map should be used as guidance to identify damaged areas, and may be less reliable over vegetated areas. It covers an area of 109 by 106 miles (175 by 170 kilometers),” NASA says.
The colors are used to identify the extent of damage in a particular area, with yellow indicating the least amount of ground and building surface change, and red indicating the greatest changes. The map is available for download here.
Less than two weeks before the Sept. 12 quake, a separate 8.1 quake hit Mexico’s southern Pacific coast. The JPL and Caltech team responded to the disaster with a similar damage proxy map, which can be downloaded here.
ARIA also works to investigate the impacts of volcanoes, landslides, fires, and other natural hazards.
“As populations grow, response to natural disasters is becoming an increasingly important part of link between science and society. We are developing tools to use the growing networks of ground-based GPS sensors and constellations of imaging satellites for hazard monitoring and response. With these new tools, we anticipate the improvement of situational awareness immediately following disasters,” according to ARIA's website.