In early August 2020, a vast explosion occurred at the port of Beirut City. The blast struck after a fire broke in a warehouse that stored ammonium nitrate, a substance that is not flammable but can produce massive explosions in case of a fire if it's confined. The explosion which was felt as far as Cyprus (240 kilometers away) resulted in unprecedented destruction with numerous buildings destroyed (about 300,000 people left homeless), more than 200 casualties and 7,500 people injured.
Before the city was rebuilt, research teams aimed at documenting the structural damage imposed by the explosion in the city and comparing ground surveys with satellite imagery obtained by the NASA Jet Propulsion Laboratory. According to Jonathan P. Stewart, Professor of Civil and Environmental Engineering at UCLA, satellite data were able to provide valid information regarding buildings that were either left undamaged or were severely impacted. However, identifying buildings with intermediate damage patterns was challenging. In-situ investigations were halted at the time of the event due to the restrictions imposed by the COVID-19 situation. Therefore, not many engineers could assess the sites of interest. The researchers found a clever way to overcome this difficulty by installing 360 degrees cameras on vehicles that were driven around Beirut.
The Geotechnical Extreme Events Reconnaissance Association (GEER) issued a report on the explosion on April 2, 2021. The building damage was highly dependent on the location of a structure with respect to the blast. “With an explosion, the damage decreases with distance and with the number of buildings between you and the blast that can deflect its effects," Prof. Stewart mentioned.
Regarding the size of the affected area, the GEER report suggests that the blast affected a surrounding area with a radius of about 4 kilometers. The port of Beirut was devastated as the explosion created a 5-meter crater while quay walls and nearby buildings collapsed. A series of grain silos in the proximity of the blast were also destroyed. In addition, the loading docks and storage yards were damaged and all goods and materials were completely destroyed. Fortunately, one section of the port which was located to the north did not suffer critical damage and it remained partially operational after the blast.
Structural impact in the city of Beirut ranged from facade damage to total collapse with some functional ramifications (e.g. broken windows or doors) being reported to residences over 4 kilometers away.