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The CBC Halifax Explosion Site


Main Page > City of Ruins > The Explosion

The Explosion

At 9:04:35 Mont-Blanc exploded with a force stronger than any manmade explosion before it.

The steel hull burst sky-high, falling in a blizzard of red-hot, twisted projectiles on Dartmouth and Halifax.

Some pieces were tiny; others were huge. Part of the anchor hit the ground more than 4 kilometers away on the far side of Northwest Arm. A gun barrel landed in Dartmouth more than 5 kilometers from the harbour.

After the Blast

The explosion sent a white cloud billowing 20,000 feet above the city.

For almost two square kilometers around Pier 6, nothing was left standing. The blast obliterated most of Richmond: its homes, apartments and even the towering sugar refinery. On the Dartmouth side, Tuft's Cove took the brunt of the blast. The small Mi'kmaq settlement of Turtle Grove was obliterated.

More than 1500 people were killed outright; hundreds more would die in the hours and days to come. Nine thousand people, many of whom might have been safe if they hadn't come to watch the fire, were injured by the blast, falling buildings and flying shards of glass.

And it wasn't over yet.

Within minutes the dazed survivors were awash in water. The blast provoked a tsunami [?] that washed up as high as 18 meters above the harbour's high-water mark on the Halifax side.

People blown off their feet by the explosion now hung on for their lives as water rushed over the shoreline, through the dockyard and beyond Campbell Road (now Barrington Street).

The tsunami lifted Imo onto the Dartmouth shore. The ship stayed there until spring.

Disputes over time: seismograph record

For many years after the Explosion there were arguments over the exact time it happened. Some people said it was 9:06, others 9:05 or 9:07. Some said it was definitely just before…or just after, or exactly at, 9 o'clock.

The last word on the subject came from the seismograph at Dalhousie University. Its record was in storage for years, until researchers Alan Ruffman and David Simpson found it at a geological observatory in New York.

The seismograph recording proves the explosion happened at 9:04:35, plus or minus 10 seconds. this allows for 0.57 seconds for the vibration to travel from the harbour to Dalhousie…and allows for the fact that the seismograph's clock was itself 10 seconds fast.

A Scientist's Report

"Buildings within a radius of half a mile of the explosion were totally destroyed and that up to one mile they were very largely rendered uninhabitable and dangerous. No section of Halifax city escaped serious damage…
More or less severe damage was caused as far away as Sackville and Windsor Junction, 9 or 10 miles (away from) the explosion… At Truro, 62 miles, and New Glasgow, 78 miles, the shock was sufficient to jar buildings very appreciably, and even to shake articles from shelves. Even as far away as Charlottetown, 135 miles, and North Cape Breton, 225 miles, the explosion was distinctly felt or heard."

Source: Prof. Howard Bronson of Dalhousie University, in a paper for the Royal Society of Canada, 1918.

Awash in Water

Of the firefighters on the motorized truck Patricia, only driver William Wells survived. As Archibald MacMechan reports in his 1918 history of the Explosion:

"The force of the explosion flung (Wells) across the street against a telegraph, or electric light pole. His own account is that he left the engine, or the engine left him, he did not know which, but anyhow they parted company. There he lay until the sea drove over the road, washing him as far as the middle of Mulgrave Park. He was drenched and almost drowned and when picked up was not expected to live. He did, however, recover and regained his usual health."

Source: MacMechan in Metson, The Halifax Explosion.


A tsunami (Japanese for "harbour wave") is popularly known as a tidal wave, but it has nothing to do with tides.

A tsunami is usually triggered when something such as an earthquake disrupts the ocean floor. If you think of the ocean as a bathtub, the effect is similar to what would happen if you moved your leg suddenly in the tub.

In the case of the Halifax Explosion, there are no scientific observations or measurements of what happened to water levels in Halifax Harbour. Those close to the shore who survived the blast itself were too dazed or too busy trying to save themselves, or others, to make detached observations at the time.

The survivors' accounts sometimes conflict with each other, but combined with what we know of the physics of tsunamis, we can get a pretty good picture of what happened.

When Mont-Blanc exploded, the blast pushed away the water around it. If you think of the ripples that radiate out from a pebble thrown into the water, that will give you an idea of the beginnings of this tsunami.

After the explosion pushed the water away, the water rushed back in, and out again. This pulsing action would have continued for a minute or so. The outward momentum carried the water well up onto the land in areas closest to the blast.

According to researcher Alan Ruffman, the tsunami would have washed up to various levels at various points of Halifax Harbour and Bedford Basin. Like those ripples in a pond, the strength of the tsunami was greater, closer to Ground Zero, and much weaker farther away.

The effect was also exaggerated by the shape of the harbour and the location of the Explosion. Ground Zero was in a confined area (The Narrows) which concentrated the effect in the area closest to Pier 6.

Did You Know

Long distance tidal wave: There are stories of ships miles away from the explosion being lifted on a great "tidal wave." They are not true. But several ships well outside Halifax heard the explosion, saw the plume of smoke on the horizon, and headed for the city to offer help.

Page Feature: Vince Coleman: An Explosion Legend

Vince Coleman was a train dispatcher with the Canadian Government Railway on the harbourfront.

As Mont-Blanc burned, Coleman's boss told his workers to evacuate. But Coleman stayed behind to send a Morse code warning to incoming trains:

"Munitions ship on fire. Making for Pier 6. Goodbye."

Mont-Blanc exploded before any trains arrived in the danger area…and before Coleman could escape.

He died in the blast, but became a Canadian legend for his dedication to his duty.

Page Feature: Constant Upham

Fire alarms from the dockyard were common. North end firefighters were used to hosing down the wooden wharves after coal embers had been dumped onto them from ships’ boilers.

The call from Box 83 on December 6 would have seemed routine if not for Constant Upham.

The Richmond storekeeper had a telephone in his home. He called several fire halls to report that he saw a ship burning in the harbour.

Constant Upham died in the Explosion.

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