This damage map of a massive explosion in Beirut, Lebanon on Aug. 4, 2020 was created by NASA's ... [+]
On the evening of August 4, two powerful explosions rocked the harbor of Beirut in Lebanon. Buildings near the explosion's epicenter were flattened in an instant. Cars in the street were thrown through the air like toys and even ships, anchored in the harbor, capsized. A huge shockwave thundered through the city. Rolling over the earth at the speed of sound, the sudden pressure burst shattered windows up to 20 kilometers (or 15 miles) away from the explosion's epicenter. More than 300,000 families have lost their homes due to the explosions, 6,000 people were injured, and 220 people were killed.
Using satellite imagery and RADAR data obtained by the European satellite program, a NASA team mapped the extent of the devastation. Synthetic aperture radar data shows changes to the ground by overlapping subsequent height measurements; this technology is usually used to map terrain changes after major events, such as earthquakes. Each square in the map represents an area of 30 x 30 meters (approximately 33 x 33 yards). In the red zones, the explosion caused the most damage, flattening buildings. Orange areas have moderate damage, as buildings partially collapsed, and areas in yellow are likely less affected.
According to ongoing investigations the explosion was caused by the deflagration of 2,750 tons of ammonium nitrate, stocked unsafely in Beirut's port district. An energy equivalent of 1,100 tons of TNT was released in an instant, excavating a 43-meter (140 ft) deep crater in the ground.
Recommended For You
Eyewitness accounts describe widespread shacking of buildings in a radius of 50 kilometers (30 miles), and trembling of the ground felt still 250 kilometers away from the explosion center. The seismic waves were recorded by the seismographic network of the Geological Survey of Israel and seismic stations along the Syrian border to Turkey, almost 400 kilometers away.
According to first estimates by geologists, the blast was equivalent to a magnitude 4.5 earthquake, comparable to the energy released by the detonation of 1,000 to 3,000 tons of TNT. The USGS gives a lower magnitude of 3.3; typically, people report feeling earthquakes larger than about magnitude 3.0, so this could fit the eyewitness accounts.
The calculated magnitude is not directly comparable to an earthquake of similar size because the explosion occurred at the surface where seismic waves are not as efficiently generated. During a surface blast, like the Beirut explosion, most of the energy goes into the air and not enough energy is transmitted into the rocks in the ground. If the explosion had occurred below the surface of the earth, the magnitude picked up be the seismographic stations would have registered higher.
#News | https://sciencespies.com/news/nasa-map-shows-devastation-caused-by-beirut-blast/
No comments:
Post a Comment