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Tragedy struck yesterday in the Lebanese capital of Beirut, with at least 78 people killed, and more than 4 000 wounded, after an explosion rocked the city in the early evening.

The blast took place near the city’s port, where it is believed that around 2 750 tonnes of ammonium nitrate, a highly explosive material, had been stored in a warehouse for six years.

Ammonium nitrate is most commonly used as an agricultural fertiliser and as an explosive, and is highly explosive when it comes into contact with fire.

An investigation is still underway to determine the exact cause of the blast, reports the BBC:

Prime Minister Hassan Diab called it a catastrophe and said those responsible must be held to account.

He spoke of a “dangerous warehouse” which had been there since 2014, but said he would not pre-empt the investigation.

Image: BBC

Local media showed people trapped beneath rubble. A witness described the first explosion as deafening, and video footage showed wrecked cars and blast-damaged buildings.

“All the buildings around here have collapsed. I’m walking through glass and debris everywhere, in the dark,” one witness near the port told AFP news agency.

The blast was heard a full 240 kilometres away, and was captured by multiple onlookers, who had begun filming after smoke billowed from the port building.

Here are a number of different angles:

In slow motion, the formation of a mushroom cloud can clearly be seen, which is most commonly associated with an atomic or nuclear bomb:

As Popular Mechanics points out, that is not the case here:

The truth is large explosions on the ground also produce the iconic mushroom cloud shape, due to simple physics.

…the physics is the same: the explosion produces hot gas that quickly rises. The air above blunts this hot gas as it tries to move upward, literally pushing it downward and forming the distinctive cap…

In an explosion, the less-dense hot air is meeting the more-dense cold air and forming it into a mushroom shape. That’s why mushroom clouds aren’t confined to nuclear explosions.

The aftermath of the explosion left large parts of the city in ruin:

The blast also comes at a troubling time for the country, reports the Telegraph, which is facing “its worst financial and economic crisis in decades”.

Residents of Beruit were encouraged by the health minister to leave the city if they could, as hazardous materials in the air could possibly have long-term, deadly effects.

[sources:bbc&popmechanics&telegraph]