Beirut
Lebanon puts port officials under house arrest and declares a state of emergency after the explosion:
Interior Minister Mohammed Fahmi had earlier told a local TV station that it appeared the blast was caused by the detonation of the ammonium nitrate that had been stored ever since it was confiscated from a cargo ship in 2014.
Ammonium nitrate is a common ingredient in fertilizer but can also be highly explosive.
The BBC has the best unclassified collection of before-and-after images. Their interactive pictures are the best way of understanding the scope of the destruction.
The Wikipedia article on ammonium nitrate includes some niche uses of the chemical:
Ammonium nitrate is used in some instant cold packs, as its dissolution in water is highly endothermic. It also was used, in combination with independently explosive “fuels” such as guanidine nitrate, as a cheaper (but less stable) alternative to 5-aminotetrazole in the inflators of airbags manufactured by Takata Corporation, which were recalled as unsafe after killing 14 people.
In the US it was the chemical involved in the 1995 Oklahoma City bombing by Timothy McVeigh which was 2 tons of ammonium nitrate and the 2013 explosion at the West Fertilizer Company in Texas where 240 tons of the chemical were stored.
It was estimated that the warehouse in Beirut had 2750 tonnes (approximately 3030 US tons) stored in it. The chemical becomes unstable at about 60% relative humidity, so storing it in a warehouse at a seaport was never a great idea.
