The Halifax Explosion a Century ago

The Halifax Explosion was a maritime disaster in Halifax, Nova Scotia, Canada, on the morning of 6 December 1917. SS Mont-Blanc, a French cargo ship laden with high explosives, collided with the Norwegian vessel SS Imo in the Narrows, a strait connecting the upper Halifax Harbour to Bedford Basin. A fire on board the French ship ignited her cargo, causing a large explosion that devastated the Richmond district of Halifax. Approximately 2,000 people were killed by the blast, debris, fires or collapsed buildings, and an estimated 9,000 others were injured. The blast was the largest man-made explosion before the development of nuclear weapons, releasing the equivalent energy of roughly 2.9 kilotons of TNT (12,000 GJ).

                                                  Halifax Explosion pyrocumulus  cloud


Mont-Blanc was under orders from the French government to carry her cargo of high explosives from New York via Halifax to Bordeaux, France. At roughly 8:45 am, she collided at low speed, approximately one knot (1.2 mph or 1.9 km/h), with the unladen Imo, chartered by the Commission for Relief in Belgium to pick up a cargo of relief supplies in New York. The resulting fire on board the French ship quickly grew out of control. Approximately 20 minutes later at 9:04:35 am, the Mont-Blanc exploded.

Nearly all structures within an 800-metre (half-mile) radius, including the entire community of Richmond, were obliterated. A pressure wave snapped trees, bent iron rails, demolished buildings, grounded vessels, and scattered fragments of Mont-Blanc for kilometres. Hardly a window in the city proper survived the blast. Across the harbour, in Dartmouth, there was also widespread damage. A tsunami created by the blast wiped out the community of Mi'kmaq First Nations people who had lived in the Tufts Cove area for generations.

Relief efforts began almost immediately, and hospitals quickly became full. Rescue trains began arriving from across eastern Canada and the north-eastern United States, but were impeded by a blizzard. Construction of temporary shelters to house the many people left homeless began soon after the disaster. The initial judicial inquiry found Mont-Blanc to have been responsible for the disaster, but a later appeal determined that both vessels were to blame. There are several memorials to the victims of the explosion in the North End.

The Explosion

At 9:04:35 am, the out-of-control fire on board Mont-Blanc finally set off her highly explosive cargo. The ship was completely blown apart and a powerful blast wave radiated away from the explosion at more than 1,000 metres (3,300 ft) per second. Temperatures of 5,000 °C (9,000 °F) and pressures of thousands of atmospheres accompanied the moment of detonation at the centre of the explosion. White-hot shards of iron fell down upon Halifax and Dartmouth. Mont-Blanc's forward 90 mm gun, its barrel melted away, landed approximately 5.6 kilometres (3.5 mi) north of the explosion site near Albro Lake in Dartmouth, while the shank of her anchor, weighing half a ton, landed 3.2 kilometres (2.0 mi) south at Armdale.

A cloud of white smoke rose to over 3,600 metres (11,800 ft). The shock wave from the blast travelled through the earth at nearly 23 times the speed of sound and was felt as far away as Cape Breton (207 kilometres or 129 miles) and Prince Edward Island (180 kilometres or 110 miles). An area of over 160 hectares (400 acres) was completely destroyed by the explosion, while the harbour floor was momentarily exposed by the volume of water that vaporized. A tsunami was formed by water surging in to fill the void; it rose as high as 18 metres (60 ft) above the high-water mark on the Halifax side of the harbour. Imo was carried onto the shore at Dartmouth by the tsunami. The blast killed all but one on the whaler, everyone on the pinnace and 21 of the 26 men on Stella Maris; she ended up on the Dartmouth shore, severely damaged. The captain's son, First Mate Walter Brannen, who had been thrown into the hold by the blast, survived, as did four others. All but one of the Mont-Blanc crew members survived.

Over 1,600 people were killed instantly and 9,000 were injured, more than 300 of whom later died. Every building within a 2.6-kilometre (1.6 mi) radius, over 12,000 in total, was destroyed or badly damaged. Hundreds of people who had been watching the fire from their homes were blinded when the blast wave shattered the windows in front of them. Stoves and lamps overturned by the force of the blast sparked fires throughout Halifax, particularly in the North End, where entire city blocks were caught up in the inferno, trapping residents inside their houses. Firefighter Billy Wells, who was thrown away from the explosion and had his clothes torn from his body, described the devastation survivors faced: "The sight was awful, with people hanging out of windows dead. Some with their heads missing, and some thrown onto the overhead telegraph wires." He was the only member of the eight-man crew of the fire engine "Patricia" to survive.

Large brick and stone factories near Pier 6, such as the Acadia Sugar Refinery, disappeared into unrecognizable heaps of rubble, killing most of their workers. The Nova Scotia cotton mill located 1.5 km (0.93 mile) from the blast was destroyed by fire and the collapse of its concrete floors. The Royal Naval College of Canada building was badly damaged, and several cadets and instructors maimed.
                                                   

                                         https://en.wikipedia.org/wiki/Halifax_Explosion