Friday, April 25, 2014

Earthquake BC and the Fraser Valley

A 6.6 magnitude earthquake hit about 40 km southeast of Port Alice on Vancouver Island shortly after 8 pm on April 22, 2014 reminding everyone that British Columbians live in a quake prone part of the world.  While few earthquakes are large enough to be felt by humans a BIG one could have a major destructive force. This article looks at monitoring, quake history, risk factors unique to the Fraser Valley and safeguarding your home.

Stephen Mullock© A Whole Lot of Shaking

Most of the monitoring done by Natural Resources Canada (NRC) stations in the province are situated on Vancouver Island and for good reason.  The real rub is west of Vancouver Island where the Juan de Fuca  and Explorer Plate are in a slow subduction wrestling match with the North American plate.  The concern is that one plate might suddenly "give" releasing energy in the form of an earthquake of a +9 magnitude and unleash a lethal tsunami.

The biggest Canadian "recorded" quake was the Queen Charlotte Islands/Haida Gwaii earthquake of August 22, 1949 of a 8.1 magnitude. However, on January 26, 1700 the Cascadia earthquake struck with a 8.7- 9.2m sending a tsunami wave all the way across the Pacific Ocean to Japan.  It extended a 1,000 km rupture from northern California to midway up Vancouver Island.  It would seem that major jolts like this come with a regularity of 400 to 500 years.  When the next is to come, no one can say with certainty.

What factors might be involved in the Fraser Valley?  Should we take some comfort that Vancouver Island is between us and the Juan de Fuca plate?  I would suggest getting prepared and if nothing happens - count that is being a good day.

I wrote recently that the Fraser Valley is unique in that it falls between the intersection of two mountain ranges, the Cascades to the south and the Coast Mountains to the north.  Tremendous plate activity has already occurred the evidence is visual just have a look around.  What I didn't know until I started to research this piece was that two fault lines run through the Fraser Valley known as the Vedder Mountain and Sumas faults. Perhaps this is the reason that an earthquake monitoring station is maintained by Natural Resources Canada on Vedder Mountain.  If you are wanting to have a look at the seismogram monitors in Canada go to the NRC  seismogram site.  It would appear that there is a greater vulnerability than I first thought.  Not to panic of course with a 400-500 years event horizon.

What can you do?

  • Purchase earthquake house insurance
  • Earthquake proof your home 
  • Develop an disaster plan and survival kit sufficient for 72 hours. 
  • Contact and become involved with your local government as they will lead the initial response to a disaster in the community.  Volunteer.

Here are some good sites to prepare for an earthquake: