The small Mediterranean resort of Sant Carles de la Rapita in southern Catalonia has long been a popular tourist destination. July is prime holiday season in Spain and back in 1978 the nearby campsite of Los Alfaques (The Sandbars) was crowded with carefree vacationers, mostly foreign nationals. Little did they know or care that a tanker truck was loading flammable liquid propylene at a state-owned refinery north of Tarragona, further up the coast. The maximum permitted load was just over 19 tonnes, but the tanker took on 23 tonnes.

Furthermore, the driver had been instructed to take the old N-340 coast road, rather than pay a toll on the parallel A-7 motorway. The combination of illegal load and penny-pinching route would have fatal consequences. Accounts of what happened as the tanker reached Los Alfaques vary. Some say a tire burst, causing the vehicle to swerve and hit a wall, rupturing the tank. Others claim the tanker sprung a pressure leak with an audible bang opposite the site, or was already leaking. In any event, it stopped outside the camp gates at around 02:35. A white cloud of gaseous propylene was carried into the camp on the breeze, drifting towards a disco as curious spectators gathered to observe the phenomenon.

When the deadly cloud got there, it found an ignition source. Flames flashed back to the tanker. It erupted instantly, a devastating BLEVE (Boiling Liquid Expanding Vapour Explosion) creating a huge fireball and large crater. Intense heat of over 1,000°F immolated everything within a 300 m (985 ft) radius, including tents, vehicles, caravans, people, the disco and all its occupants.

Over 150 were killed instantly, including the tanker driver, and more than 200 were severely injured. Many burn victims would later die in hospital or be scarred for life.

When was the Los Alfaques Disaster: July 11 1978

Where was the Los Alfaques Disaster: Sant Carles de la Rapita, near Alcanar, Catalonia, Spain

What was the Los Alfaques Disaster death toll: Around 220 died (on the day and subsequently).

You should know: Four employees of the ENPETROL refinery where the liquid propylene was loaded and two from the client company (Paular, now Repsol, also state-owned) were convicted of criminal negligence and received short prison terms, later quashed or suspended. The two companies paid out massive compensation to survivors and victims’ families.