The Beirut Blast Explained: What Caused the 2020 Explosion?

The Beirut blast of August 4, 2020 was caused by the detonation of approximately 2,750 tonnes of ammonium nitrate stored unsafely in Hangar 12 of Beirut's port for six years. The explosion killed at least 218 people, injured more than 7,000, and left an estimated 300,000 residents homeless. It ranks among the most powerful accidental explosions ever recorded, with a shockwave felt as far as Cyprus, 240 kilometres away.

How Did 2,750 Tonnes of Ammonium Nitrate End Up in Beirut's Port?

The chemical arrived aboard the Moldovan-flagged cargo ship MV Rhosus in late 2013. The vessel, owned by Russian businessman Igor Grechushkin, had been chartered to transport the ammonium nitrate from Batumi, Georgia, to Mozambique. Financial difficulties forced the ship to make an unscheduled stop in Beirut, where port authorities impounded it over unpaid debts and safety violations. Lebanese customs officials offloaded the cargo into Hangar 12 in 2014 and sent at least six letters to judges over the following years warning of the danger — all went unanswered. The ammonium nitrate sat in the warehouse through sweltering summers without proper ventilation, firefighting infrastructure, or security.

What Triggered the Explosion on August 4, 2020?

Investigators believe a fire broke out in Hangar 12 during welding or cutting work meant to seal a hole in the warehouse door. Workers had reported the gap as a security risk. Footage captured the fire spreading rapidly, triggering smaller secondary explosions — likely from fireworks also stored nearby — before the full ammonium nitrate cache detonated at 6:08 p.m. local time. The blast created a crater 43 metres deep and 124 metres wide, obliterated the port, and sent a mushroom-shaped cloud over the city. The explosion measured the equivalent of a 3.3-magnitude earthquake and was recorded by seismic stations across the Middle East.

Death Toll, Destruction, and the Scale of the Disaster

The blast devastated the neighbourhoods of Gemmayzeh, Mar Mikhael, and Achrafieh — historic districts of dense residential and commercial buildings. Hospitals closest to the port, including St. George Hospital, were themselves severely damaged, hampering emergency response. Estimated property damage reached $15 billion in a country already in economic freefall. The World Food Programme warned that the destruction of Beirut's main grain silo — which held roughly 85 percent of Lebanon's wheat reserves — threatened a food crisis. International aid poured in from France, the United States, and Gulf states, though political dysfunction meant much of it bypassed the Lebanese government entirely.

Political Fallout and the Stalled Investigation

Prime Minister Hassan Diab's government resigned on August 10, 2020, just six days after the blast, citing systemic corruption. Lebanon's internal investigation became mired in legal battles as senior officials used parliamentary immunity to block questioning by lead investigator Judge Tarek Bitar. By 2023, no senior official had been prosecuted. Human Rights Watch called the obstruction a deliberate effort by Lebanon's political elite to shield themselves from accountability. Families of victims continued to demand an independent international inquiry, arguing that a domestic probe could never deliver justice in a system built on impunity.