Beirut blast was like a small nuclear weapon, says explosives expert

Fatalities would have measured in 'thousands, if not tens of thousands' if warehouse had been just 400 metres closer to city

A woman stands inside a damaged restaurant. AP Photo

People and employees attend a mass over the victims who were killed in the blast, at the Al-Roum hospital at Ashrafieh area in Beirut. EPA

Workers are pictured at the devastated site of the explosion at the port of Beirut. EPA

A man sleeps near a damaged car near the site of Tuesday's blast in Beirut's port area. REUTERS

Workers line at the devastated site of the explosion at the port of Beirut. EPA

French President Emmanuel Macron visits the devastated site of the explosion at the port of Beirut. EPA

People and employees attend a mass over the victims who were killed in the blast, at the Al-Roum hospital at Ashrafieh area in Beirut. EPA

A view of the port of Beirut on January 25, 2020, left, and on August 5, 2020, a day after the explosion. AFP

Bride Israa Seblani poses for a picture in the same place where she was taking her wedding photos at the moment of the explosion. Reuters

People stand with their belongings as they leave their damaged homes. Reuters

A Lebanese man shows injuries on his back after the massive explosion in Beirut. EPA

Men are seen sitting inside a damaged home, following Tuesday's blast in Beirut's port area. Reuters

A pedestrian takes photos of a badly damaged building in Beirut. Bloomberg

Lebanese Druze clerics check damaged cars. AP Photo

A statue representing the Lebanese expatriate is seen in front of a building that was damaged by the explosion. AP Photo

People walk with their belongings in the area of Mar Mikhael and Gemayzeh. EPA

The curtains in the rooms of the Le Gray hotel in the Lebanese capital Beirut swaying in the wind. AFP

A view of a damaged Fransa Bank. EPA

People check damaged vehicles. EPA

Volunteers clean the streets amid the wreckage. Reuters

People carry belongings after evacuating their damaged housing units at area of Mar Mikhael and Gemayzeh. EPA

A destroyed Bank Audi SAL branch stands in Beirut. Bloomberg

A worker wearing a protective face mask stands at the entrance to a destroyed Fransabank SAL branch in Beirut. Bloomberg

Volunteers carry brooms as they walk to clean the streets. Reuters

A woman sits in front of a damaged building. EPA

A general view of the Beirut port area after the massive explosion. EPA

An aerial view shows the massive damage done to the Electricity of Lebanon building. AFP

A view of the damaged building of the Lebanese fashion designer Zuhair Murad. EPA

Volunteers gather aid supplies to be distributed for those affected by Tuesday's blast. Reuters

Lebanese men clears rubble, one day after the explosion at the Beirut Port, in the Gemayzeh area. EPA

Lebanese youth salvage a velvet sofa from a destroyed apartment in the Gemayzeh area of Beirut. EPA

Lebanese activists take part in a campaign to clean the damaged neighbourhood of Mar Mikhael. AFP

An injured Lebanese shop owner sits at her desk selling her wares. EPA

The 2,700 tonnes of ammonium nitrate responsible for flattening much of Beirut on Tuesday detonated with the equivalent power of a small nuclear weapon, a leading explosives expert has told The National.

The blast - that of approximately 1.5 kilotons of TNT - was one-tenth of the explosive yield of the Hiroshima atomic bomb that was dropped on the Japanese city 75 years ago today, Professor  Andrew Tyas said.

The explosion killed at least 137 people and caused up to $15 billion in damage to houses and infrastructure, leaving 300,000 people homeless. The more than 5,000 people who were injured overwhelmed the hospitals that were still able to function after the impact.

Had the warehouse storing the stash of chemicals been 400 metres closer to the city, however, fatalities would have measured in the “thousands, if not the tens of thousands”, the professor of blast protection engineering at Sheffield University said.

He and his team spent hours examining the size of the explosion using Google maps to measure the radius of damage that stretched several kilometres.

“This has the equivalent yield to something that's on the scale of the smallest tactical nuclear weapon,” Prof Tyas said

The major damage within a kilometre radius also led him to conclude that it had been caused by a “high explosive yield equivalent, which would be in the order of about 10 per cent of the Hiroshima bomb”.

Prof Tyas added that the blast was similar to a small nuclear event. "Which clearly this wasn't, but it was getting on towards that sort of scale," he said, before telling The National of his shock at the catastrophe.

“At first, I was almost unable to process the scale of the explosion. It was almost as if I didn't want to believe it was quite on that scale. Then we started doing the numbers and it was very sobering, realising that this was bigger than most things that have ever happened in an urban environment before.”

Prof Tyas and his team were also quick to understand that the sheer size of the explosion ruled out an extremist attack. A large terrorist vehicle bomb would, he said, perhaps contain one or two tonnes of TNT.

“You're looking [with this incident] at something that's 1,000 times bigger than what would normally be classed as a very, very large, devastating terrorist attack,” he said.

“We realised very quickly that there's no way this could have been a conventional weapon attack. It's an order of magnitude bigger than anything you'd expect to see from a normal terrorist explosive attack. So the obvious thing that was pointing towards was some sort of industrial accident.”

There are fears that people could suffer respiratory problems in Beirut from the resulting toxic cloud, which is similar to one that occurred after an ammonium nitrate explosion in Tianjin, China, five years ago.

“If it rains into a cloud like that [one did], you can get things like nitric acid condensing out of it,” said Prof Tyas, whose engineering research concentrates on protecting people from blasts and impact.

The massive grain silo situated right next to the warehouse, which may have held up to 120,000 tonnes of grain, may have acted as a massive sandbag but was unlikely to have saved lives. The blast would have gone both over the top and around it.

“Instinctively, you would think it helped protect anyone who was in that immediate region, but the problem is just the magnitude of the explosion is so big,” he said. “Even an 80 or 90 per cent reduction in the blast loading is still likely to end up in pressures that are fatal to anybody around there.”

Prof Tyas believes that the detonation was possibly the result of a fire, either from a dropped cigarette or electrical fault, that then initiated the massive stockpile of ammonium nitrate.

The explosives expert said that, to prevent future catastrophes, authorities in the first instance should store the deadly substances far from urban areas.