Silvertown explosion

The Silvertown explosion occurred in Silvertown in West Ham, Essex (now part of the London Borough of Newham, in Greater London) on Friday, 19 January 1917 at 6.52 pm. The blast occurred at a munitions factory that was manufacturing explosives for Britain's World War I military effort. Approximately 50 tons of trinitrotoluene (TNT) exploded, killing 73 people and injuring more 400, as well as causing substantial damage in the local area. This was not the first, last, largest, or the most deadly explosion at a munitions facility in Britain during the war: an explosion at Faversham involving 200 tons of TNT killed 105 in 1916, and the National Shell Filling Factory, Chilwell exploded in 1918, killing 137.

The factory was built in 1893 on the south side (River Thames side) of North Woolwich Road (now the A1020, nearly opposite Mill Road) by Brunner Mond, a forerunner of Imperial Chemical Industries, to produce soda crystals and caustic soda. Production of caustic soda ceased in 1912, which left part of the factory idle. Two years into the war, the Army was facing a crippling shell shortage. The War Office decided to use the factory's surplus capacity to purify TNT, a process more dangerous than manufacture itself, although the factory was in a highly populated area. Despite opposition from Brunner Mond, production of TNT began in September 1915. The method used was invented by Brunner Mond chief scientist F. A. Freeth, who believed the process to be "manifestly very dangerous". The plant continued to purify TNT at a rate of approximately 9 tons per day until it was destroyed by the explosion.
Another plant, at Gadbrook, was built in 1916 and was producing TNT at a higher rate than the Silvertown factory, away from populated areas, with more stringent safety standards. The volume of explosives produced at this factory effectively subsumed the Silvertown plant's output, but both were nevertheless in full production.

The Millennium Mills following the explosion

On 19 January a fire broke out in the melt-pot room, and efforts to put it out were under way when approximately 50 long tons (51 t) of TNT ignited at 6:52 pm. The TNT plant was destroyed instantly, as were many nearby buildings, including the Silvertown Fire Station. Much of the TNT was in railway goods wagons awaiting transport. Debris was strewn for miles around, with red-hot chunks of rubble causing fires. A gasometer was destroyed on Greenwich Peninsula, creating a fireball from 200,000 cubic metres (7,100,000 cu ft) of gas. Several thousand pounds' worth of goods were also destroyed in nearby warehouses, estimated by the Port of London Authority to span 7 hectares (17 acres).
Seventy-three people were killed (sixty-nine immediately, and four later from their injuries), and more than 400 injured. Up to 70,000 properties were damaged, 900 nearby ones destroyed or unsalvageably damaged; the cost was put at either £250,000 or £2.5 million. The comparatively low death toll for such a large blast was due to the time of day. The factories were largely empty of workers (there were fewer than forty in the TNT factory itself), but it was too early for the upper floors of houses (which sustained the worst of the flying debris damage) to be heavily populated. Also, it occurred on a Friday, when fewer people were around the factory. However, several professional firemen and volunteers fighting the earlier fire were killed or seriously injured in the explosion. For comparison, 8 tons of TNT exploded at the National Shell Filling Factory, and killed 137 people; an explosion at Split Rock, New York in 1918 killed 50–52 people with 1–3 tons of TNT.
Reportedly, the explosion also blew the glass out of windows in the Savoy Hotel and almost overturned a taxi in Pall Mall, London, the fires could be seen in Maidstone and Guildford, and the blast was heard up to 100 miles (160 km) away, including Sandringham in Norfolk and along the Sussex coast. Although the blast was heard at a great distance, it was not heard uniformly across the whole intermediate distance, owing to atmospheric effects caused by refraction of the sound waves.