population, Vancouver

B.C.’s ‘Big Ones’ : a survey of recent earthquakes

The last tsunami to hit B.C. encountered much less infrastructure

The waves crashed through their houses as they frantically awoke and tried to escape. Moments earlier, the shaking was so vicious people lay on the ground, nauseous. The 9.0 magnitude offshore quake decimated the coastal community, leaving no survivors.

Through oral histories we know the indigenous people of Pachena Bay on Vancouver Island’s southwest coast were completely wiped out by the Jan. 26, 1700 quake. Recently unearthed imperial documents confirm the resulting tsunami also wreaked havoc across the Pacific on the people of Japan.

B.C.’s last ‘big one’ occurred over 300 years ago, and seismologists say the province is due for another in the next two hundred years.

The B.C. coast experiences over 1,200 earthquakes a year and six out of Canada’s 10 biggest recorded quakes have happened in the region.

The 1700 quake and was very similar in strength to last week’s 8.9 magnitude quake near Japan, but B.C. has also seen other major quakes in its more recent history.

Canada’s second-biggest recorded quake happened off the coast of Haida Gwaii in 1949. A magnitude of 8.1, it was strong enough to tip cows on Haida Gwaii and be felt as far away as Seattle. Across the Hecate Strait in Prince Rupert buildings swayed and windows crashed down.

Though stronger than the 1906 quake that killed thousands and almost destroyed San Francisco, the Haida Gwaii quake didn’t kill anyone because the closest-hit areas had low population densities.

B.C.’s deadliest quake — also its biggest onshore earthquake in history — killed two people when it struck the middle of Vancouver Island during a Sunday morning on June 23, 1946.
The 7.3 magnitude quake generated a large wave that drowned one person on the coast in a capsized a boat and caused one person to die from a heart attack in faraway Seattle. The epicenter was just west of Courtenay and Campbell River and nearby communities suffered considerable structural damage.

Terrified Victoria and Vancouver residents ran into the streets as a number of chimneys there collapsed and people as far as Portland felt shaking.

The whole Pacific Northwest coast is a unique geographical region because it is one of the few places in the world where all three earthquake-causing movements can occur.

The tectonic plates of North America’s Pacific coast are constantly moving at about the same pace a fingernail grows.

B.C.’s earthquakes are caused by plates colliding, sliding past each other or moving apart.

B.C.’s biggest quakes in recent history:

  • 1700: Earthquake off west coast of Vancouver Island, decimated indigenous people of Pachena Bay and was recorded by Japanese imperial officials. Presumed scale: 9.0
  • 1949: Offshore of Haida Gwaii, this quake strong enough to tip over cows and be felt in Seattle. Scale: 8.1
  • 1970: South of Haida Gwaii, caused no known casualties. Scale: 7.4
  • 1946: Centre of Vancouver Island, largest onshore quake caused extensive damage to island communities and two deaths, one man died of a heart attack in Seattle. Scale: 7.3

These quakes were first recorded scientifically in 1898 by a seismograph placed in Victoria. By 1920, there were six seismograph locations throughout Canada.

National Resources Canada upgraded their network of seismographs in the ’90s and various universities also monitor separate seismographs.

By Mike Hager

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