When The Earth Shook: The Ripple Rock Explosion

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Canada has something about non-nuclear explosions. We have the famous Halifax Explosion of 1917 that released the equivalent of 2.9 kilotons of TNT and was the largest man-made explosion prior to the development of nuclear weapons.
That isn’t what this article is about though. This article is about another famous explosion that many in Canada have forgotten about. It is the Ripple Rock Explosion, and it is one of the largest non-nuclear explosion to ever happen.

First, a bit of background on Ripple Rock itself. This underwater mountain sits at Seymour Narrows along the Discovery Passage in British Columbia. Close to Campbell River, it presented a significant hazard to boats coming through the area.
George Vancouver wrote in his diary in 1792 that it was one of the vilest stretches of water in the entire world.
Over the years, many ships would hit the rock that was only a few feet below the water at low tide. The eddies that were formed by tidal currents around the rock also presented a significant hazard to ships.
Named by Captain Richards because of the standing waves that its summits made as the tidal current moved through the straight, it would continue to prey on ships until 1958. More on that later though.

The first large ship to ever hit the rock was the USS Saranac, which crashed into it in 1875 on its way to Alaska. From that point until 1958, 20 large ships and 100 small ships were sunk or badly damaged on the rock. It is known that at least 110 people drowned in the accidents caused by the rock.
One such ship was the USS Wachusett, which passed through the narrows during a strong ebb and became caught in an extremely large whirlpool. This caused it to strike heavily on Ripple Rock, losing a large portion of its false keel and splintering heavily.

As soon as the first ship hit the rock in the 1800s, it was decided that the rock had to go and an explosion of monumental proportions was needed. One plan had a bridge being built to connect Vancouver Island with Blue Inlet, using the rock as a support but that was abandoned in the 1860s in favour of eventually destroying the rock.
In 1931, a Canadian marine commission recommended removing the rock completely but it would be over a decade until the government gave permission to do so.
The first attempt to destroy the rock with explosives was in 1943. Floating drilling barges were tasked with drilling into the rock to blast it into pieces. This approach was abandoned quickly as cables tended to break every 48 hours.
In 1945, another attempt was made using two large overhead steel lines but this was abandoned when only 93 out of 1,500 controlled explosions were successful.

In 1953, the National Research Council of Canada commissioned a feasibility study on planting explosive charges underneath the peaks of the rock. Three companies, Northern Construction Company, J.W. Stewart Limited and Boyles Brothers Drilling Company were granted the contract, worth $3 million.
The United Kingdom’s Atomic Weapons Research Establishment were very interested in this explosion as it was going to be a very large, non-nuclear, explosion.

From November of 1955 to April of 1958, 75 men working in three shifts built a 500 foot vertical shaft from Maud Island, and a 2,370 foot long horizontal shaft to the base of Ripple Rock. Two more main shafts were built from the twin peaks. A total of 1,270 metric tons of Nitramex 2H explosives were used. This was 10 times what would have been used for an explosion above water. There were worries by some that it would destroy Campbell River 40 kilometres away, while some worried that a tsunami would hit Japan, or that millions of fish would die. A few people theorized that it would even cause the Big One, an earthquake many in British Columbia have been expecting for years.

On April 5, 1958 at 9:31 a.m., the explosion took place. A total of 635,000 metric tons of rock and water were displaced by the explosion. Rocks and debris were thrown 1,000 feet into the air. The blast was large enough that it cleared 45 feet of vertical rock, providing ships with plenty of room to go over. While it was a very large explosion, there was almost no noise as the water muffled the majority ofi t.

As for the destructive aspects, there was a brief 25-foot tsunami, and a few fish died, but that was it. The only damage that was reported was to a wall clock at a mining clock at Quadra Island.

The RCMP were on hand for the explosion to ensure no one would be anywhere within three miles of the explosion. TV crews and engineers were housed in a bunker. The explosion is now a National Historic Event and it was seen live on CBC Television coast-to-coast. It was one of the first live coast-to-coast television broadcasts in Canadian history.

Today, as many as 20 large cruise ships a day sail past Campbell River during the peak cruise season.


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