July 29 – August 5, 2020. (Click image for full view.)
On August 4, 2020, a devastating explosion shook the port area around Beirut, Lebanon. After the incident, scientists used satellite radar images to map the extent of the damage and help identify areas where people may need help.
According to the Associated Press, a fire near the harbor ignited a large nearby store of ammonium nitrate, a highly explosive chemical often used in fertilizers. At least 135 people died, about 5,000 were injured, and at least 300,000 people were left homeless. Losses from the blast are estimated to be at least $ 10 to $ 15 billion, according to news reports.
The image above is a proxy card for damage created by scientists connected NASAThe team of Advanced Rapid Imaging and Analysis (ARIA) and the Earth Observatory of Singapore (EOS). Dark red pixels represent the most damage, while orange and yellow areas are moderately or partially damaged. Each colored pixel represents an area of 30 square meters (about the size of a baseball diamond).
The team at ARIA (NASA Jet Propulsion Laboratory) and EOS examined data on synthetic aperture radar (SAR) collected before and after the explosion, mapping changes in the land surface and built structures. SAR instruments send pulses of microwaves to the earth’s surface and listen to the reflections of those waves. The radar waves can penetrate cloud cover, vegetation, and the darkness of the night to detect changes that may not appear in visible light images. When the earth’s crust moves due to an earthquake, when dry land is suddenly covered by floodwaters, or when buildings are damaged or rebuilt, the amplitude and phase of reflection of radar waves in those areas changes and the satellite indicates that there is something on the ground change.
While other U.S. and international agencies play more direct roles in responding to disasters, NASA plays a role in providing observations and analysis. In recent decades, NASA has actively built up its ability to share Earth observations that can improve the prediction, preparation, response, and recovery of natural and technological disasters. For example, NASA often responds to calls for data and imagery of the International Charter for Space and Major Disasters.
“We are looking at areas of likely exposed populations and fragile infrastructure, as well as areas of social stress and crisis. We model and map risks, while also tracking emissions, debris, damage to infrastructure, and other effects from issues such as volcanic eruptions, fires, industrial accidents, earthquakes, and floods, ”said David Green, head of NASA’s disaster relief team. “Our observations and analyzes can help our partners raise their situational awareness of systemic risks and of real-time events, leading to better informed decisions and early action.”
Image from NASA’s Earth Observatory by Joshua Stevens, with custom data from Copernicus Sentinel (2020) processed by ESA and analyzed by Singapore’s Earth Observatory (EOS) in collaboration with NASAJPL and Caltech, Landsat data from the US Geological Survey, and data from OpenStreetMap. Story by Esprit Smith, NASA’s Earth Science News Team, and Michael Carlowicz.
