Yesterday, five earthquakes, including two M6.0 jolts, struck off Vancouver Island, British Columbia, Canada.
Now seismologists say Vancouver Island is overdue for a M7.0 earthquake and has entered a period of time where an additional M9.0 mega-thrust rupture earthquake, likely to cause a tsunami, can be expected.
While the region northwest of Vancouver Island’s northern end experiences frequent seismic activity, it has been particularly active yesterday, Dec. 23rd.
A series of five offshore earthquakes took place yesterday morning, ranging from 4.7 – and increasing in intensity to two 6.0-magnitude quakes.
Meanwhile, a sixth earthquake, a M4.3, has hit the offshore region north of Vancouver on December 23, on Haida Gwaii at 9:32 p.m. at a depth of eight kilometres (five miles).
The last big Vancouver Island earthquake struck Courtenay in 1946 and measured M7.3 on the Richter scale. The GSC says quakes of this magnitude should happen every decade, so the Island is about 70 years overdue.
But something even more terrifying is lurking… Seismologists say we have entered the timeframe to expect a magnitude 9 mega-thrust rupture earthquake too.
These Cascadia Subduction Zone earthquakes happen every 200 to 800 years, and the last one occurred 300 years ago.
If it hits magnitude 9, the Big One will cause a tsunami, wreaking havoc on some coastal communities on the Island.
While storms often whip up 100 or 200 metres worth of surface water, tsunamis move the whole water column, several kilometres of water, at over 700 km per hour, close to the speed of a jetplane.
Now, earthquake Canada collaborates with the nearby Institute of Ocean Sciences (IOS), whose world-class programmers and super computers model tsunami effects.
One of the worst-case scenario predicts a 10-meter-high tsunami, wrapping around the Island and being 4 or 5m by the time it hits Victoria, and 1 or 2m when it reaches Vancouver.
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