EXPERT REACTION: Massive explosion rocks Lebanon's capital Beirut
Explosions have rocked Lebanon's capital Beirut, killing at least 78 people, injuring thousands more, and sending an enormous blast wave across the city that shattered windows, knocked down doors and shook buildings. Lebanon’s Prime Minister, Hassan Diab, said the main blast at Beirut’s port was caused when an estimated 2,750 tons of ammonium nitrate ignited. He said the chemical had been left unsecured for six years in a warehouse, and vowed to punish those responsible. Below Australian experts discuss the disaster response and the chemical involved.
Organisation/s: Flinders University, The Australian National University, The University of New South Wales, Bushfire and Natural Hazards CRC, University of South Australia, Victorian Institute of Forensic Medicine
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
On Tuesday, an ammonium nitrate explosion at a port in Beirut brought destruction to the Lebanese capital, killing more than a hundred people.
The accident was due to the explosion of 2,750 tonnes of ammonium nitrate fertilizer stored in a warehouse. The ammonium nitrate fertilizer is a lightly-explosive material that has been involved in many explosion tragedies. For instance, in 2015, a disaster caused by 800 tonnes of ammonium nitrate explosion struck in Tianjin, China, killed 165 people. Whereas the Beirut explosion is a larger scale where nearly all buildings within a radius of 250 metres were damaged.
The cause of ammonium nitrate explosions, is generally attributed to several factors including localised high temperature, localised increase in substance concentration and the presence of catalytic agents. For instance, if the ammonium nitrate fertiliser has been exposed to water evaporation on prolonged heating and the containment equipment is poorly insulated, the concentration of explosive substance will increase, thereby increasing the probability of explosion in a confined space.
Poor maintenance of the ammonium nitrate storage facilities may be another contributing factor. Given most storage facilities are made of metals, they are susceptible to corrosion. Metal corrosion can produce chromates, chromium compounds and chlorides, which are dangerous explosion catalysts.
Once all the necessary explosion conditions are met, the fire/localised high temperature can eventually trigger the ammonium nitrate explosion. Prevention of such explosion can be done be minimising all the mentioned explosion triggering factors.
The claim that an explosion in a fireworks storage area set off a nearby Ammonium nitrate warehouse containing 2750 tons of ammonium nitrate is credible and consistent with the two consecutive explosive clouds seen in video footage. This seems unlikely to be the work of a malicious or external actor. My conclusion based on the evidence so far is that it was an industrial accident.
Ammonium nitrate has enormous expansive capacity when it is used as an explosive which is why ammonium nitrate/fuel oil (ANFO) is often used for quarry blasting and improvised explosive devices.
The blast effect in Beirut was likely to cause major damage to buildings within I km of the blast and broken windows at up to 5 km. Most of the casualties will have been caused by collapsing buildings and flying debris - particularly shards of glass.
Associate Professor Stewart Walker is from the school of Forensic, Environmental and Analytical Chemistry at Flinders University. Stewart's research interests include Ammonium Nitrate and other Improvised Explosives.
Ammonium nitrate is classified as a Dangerous Good (Australian Code for the Transport of Dangerous Goods by Road & Rail (ADG Code), 7th Edition).
It is classified as 'not flammable' but will support a fire by providing oxygen to burn with a 'risk of explosion'.
Ammonium nitrate contains two groups: the ammonia (NH4+) containing a nitrogen and four hydrogens, which provide the fuel, and the nitrate that comprises of a nitrogen and three oxygens (NO3-) that provide the oxygen necessary for combustion. Because it contains both groups required for a fire, if heated then the three components of the fire-triangle are present (a fire requires the right proportions of fuel, oxygen and heat).
An explosion occurs when a large amount of an energetic substance detonates, producing a large volume of confined, hot gases that expand and cause a shock wave. The video footage of the incident show initial white/grey smoke followed by an explosion that released a large cloud of red/brown smoke and a large white 'mushroom cloud'. These indicate that the gasses released are white ammonium nitrate fumes, toxic, red/brown nitrous oxide and water.
Other incidents have occurred where ammonium nitrate in storage or transit has caused an explosion, with widespread destruction to the surrounding area. Incidents in Australia involving transportation include a truck carrying ammonium nitrate that experienced an electrical fault and a fire and exploded, killing three people in Taroom, Queensland on August 30 1972 and in Wyandra, Queensland on September 6 2014 where a truck carrying ammonium nitrate exploded after rolling, destroying a bridge.
Implementation of safe handling and risk assessments have kept the number of incidents involving ammonium nitrate down.
This is clearly a very significant explosion, and the reported number of deaths is likely to be far higher than currently identified.
Ammonium nitrate is an important fertiliser, but also a key component in improvised explosives around the world. The Oklahoma bombing in 1995 involved 3-4 tonnes of the material, and it has been alleged that as much as 2,600 tonnes has been involved in Beirut's case. Following the Oklahoma bombing, federal restrictions in the US were introduced. Our research group computer modelled the possible effects of merely a 5 tonne ammonium nitrate/fuel oil (ANFO) device on the Adelaide CBD in the mid-‘00s, and the results were several 100 dead and 1000s injured. Shortly after, more stringent accounting of an agent that clearly still has utility in agriculture was introduced in Australia.
This explosion can be considered as a ‘high order’ explosion, with an obvious blast wave seen to be propagated from a massive secondary explosion, that followed on from the event. This has significant implications for the number and types of casualties that might be expected.
Primary injuries are blast-related, as a consequence of the overpressure wave interacting with the hollow space in victims; lung injuries are often survived, but subsequently fatal, and bowel injuries are common.
Secondary injuries are caused by flying debris; effectively environmental shrapnel.
Tertiary injuries are as a consequence of being thrown by the blast, and quaternary injuries by other features such as inhalation.
The cause of such a blast will still be under investigation - whether it was accidental or deliberate is still unclear. Given the geopolitical history of the region, either is still possible.
From the video coverage of the event, this is typical of a substance undergoing a transition from 'initiation' to 'detonation'.
A large plume of smoke is seen initially (the initiation phase), which then transitions almost instantaneously into detonation with a characteristic rapid shock wave and mushroom cloud, followed by a vigorous but slower expulsion of debris.
Ammonium nitrate is a common solid fertiliser that is relatively safe by itself, although a strong oxidant, but highly dangerous when contaminated by any kind of fuel, such as oil or organic material, even in just a few per cent. In the presence of heat, such a mixture can easily lead to catastrophic outcomes. The scale here suggests large quantities were involved.
Explosions and fire resulting in mass deaths are one of the most difficult challenges confronting forensic teams as they go about the painstaking work of working out what happened and identifying the victims in order to return them to their families and loved ones.
Recovering the bodies from the scene of the disaster can be dangerous, particularly when there is extensive structural damage to buildings.
The task undertaken by forensic pathologists, dentists, scientists and mortuary specialists, in dealing with the often fragmented remains, is both scientifically and emotionally challenging. Applying the Interpol DVI (disaster victim identification) guidelines is critical in ensuring that this humanitarian task is performed quickly and reliably.
The Lebanon explosion has illustrated the dramatic impacts of a low probability, high consequence disaster event.
Emergency management organisations in Australia are increasingly focused on planning for severe to catastrophic disasters. Ultimately, though, it is difficult to be entirely prepared for such severe disasters when they occur, requiring plans to be adaptive and flexible.
Around the world, first responders to catastrophic disasters are often community members. A major disaster occurring concurrently with the COVID-19 pandemic will introduce additional complexity to any response effort.
After the initial response efforts have concluded, the impacted communities will be faced with a longer effort to ultimately recover from this disaster. Major hazardous industries in Australia are regulated to minimise the risk of similar incidents happening here.
Ammonium nitrate is not combustible and cannot burn but it can act as an oxidant source to facilitate the combustion of other materials. It can be an explosive substance because it contains nitrate as an oxidant source in close contact with ammonium as a fuel source. When heated sufficiently, ammonium nitrate decomposes to produce gases, which may include nitrogen dioxide and this increases the risk of explosive detonation, especially if in a confined environment. The risk is also increased if there are contaminants present, with only a very small amount of contaminants being required to cause unpredictable behaviour of ammonium nitrate when heated.
Where the health system or other critical infrastructure is already strained, this leaves the population particularly vulnerable to tragic events such as this, as the system has little or no spare capacity to respond to the surge in demand.
Just as we have seen with COVID-19 overwhelming the supply of ventilators and intensive care beds in hospitals, a disaster like we have seen in Lebanon can suddenly overwhelm the supply of a wide range of facilities. The sad result is that lives that could have otherwise been saved will be lost.
The challenge for the global community is to find ways to help all nations to strengthen their health, water, food, communications, education and other critical infrastructure.
Preparation is always much cheaper than response, if we can find ways to afford it.
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