Earthquake Risk Heightened Over Next Few Weeks

Posted by Karl Lundgren on

Roughly every 14 months the Pacific Northwest goes through a seismic cycle known as a slow-slip event.  For about a two to four week period the region will experience thousands of small earthquakes, unfelt to the residents of the region.  However, not all the earthquakes associated with slow-slip events go unfelt.  Residents of Vancouver Island and the BC Lower Mainland will no doubt remember December 29, 2015 when a 4.7 magnitude quake struck in the late hours of the evening near Victoria rattling houses across Southwestern, BC.  If you didn’t feel it, you sure heard about it at work or on social media.  It was the talk of the town for weeks following the event.  The tremendous overreaction of residents showed how drastically under-prepared and in denial many of us are.

This quake was one of almost 8000 earthquakes during the last slow-slip cycle, which occurred from December 22, 2015 to January 16, 2016.  I’m sure some of you are already using your hands to count out when the next slow-slip event is going to happen.  I’ll save you the trouble.  14 months from December 22, 2015 would be February 22, 2017, but since the 14 month window is approximate the next slow-slip cycle could start any day now.  In fact, according to the Earthquake Early Warning British Columbia Facebook Page it may have already started, yesterday.  The page is run by Kent Johansen a Research Engineer at UBC, and he's been keeping a very close eye on things in anticipation of the next slow-slip cycle.

In a CBC article last fall, Alison Bird, an Earthquake Seismologist for the Geological Survey of Canada, said "What we think is happening is that whenever there's that reversal… it's loading extra stress onto the locked zone… It could be a last straw scenario, just that little bit of extra stress that’s going to cause that rupture to trigger … the megathrust earthquake.”

Now this isn't to say that the Big One could only happen during a slow-slip event, but the odds are significantly higher that it will.  Kind of like how the odds of getting in a car accident are increased during rush hour or bad weather.

So we have a pretty good idea of when slow-slip events are going to occur, and there's a heightened risk of the Big One occurring during slow-slip events, so why aren't we more aware of slow-slip events?  Bird said that the information is available on their website, and they used to send out press briefings all the time, but it's hard to get people interested in an event that happens so regularly with no impact.
That's the problem with the Big One.  It happens so infrequently that it's easy to forget about or ignore, but it's coming.  It's coming whether you or possibly your descendants are prepared or not.  We need to be smarter about how we approach emergency preparedness in BC.  If risk is heightened during slow-slip events, then leading up to slow-slip events would be a very good time to make sure your household is prepared.  Have an earthquake kit and a plan for your family.  Check the supplies for expiry and sit down as a family to reinforce your emergency plan.

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  • What about Powell River? There is any risk of a tsunami?

    Maritza on
  • Thanks for posting plus the great comments … will adhere to the recommendations.

    Homer on
  • The rockeys were brought ?from a major earthquake!!!easy to figure out

    Mike on
  • Gordon Noyes, I study geogazards. There is no need to worry about a tsunami reaching Courtenay. If you’re on the east coast of Vancouver Island, the wave energy of a tsunami will dissipate before ever reaching that area. However, due to the type of rock material most of Courtenay is built upon, you will be at a high risk of liquefaction.

    Sarah McKenzie on
  • I am from an Indian decent this is passed from generation we have grown up to fill our pantry with cans nd pkgs of food most time we end up throwing them out because they have expired and we born to buy bulk. In Canada I notice people will buy few thIngs to last which is so sensible and money savings but always see to run out if stuff and having to as the neighbour. Now I have plan besides a kit always keep extra supplies of canned food and water for survival and have gas full so u can least make food outside to survive if no power and keep solar lights cause you going thank me I was right

    Joti on

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