Monday, October 29, 2012

Haida Gwaii Earthquake

First off, the public reacted quickly in many locations on the coast in response to a possible Tsunami.   I am impressed and much more hopeful that when a major earthquake happens on the BC coast people are better prepared to deal with it.

Second, the earthquake was large but still a single point and in a location far enough away from the nearest settlements to not be one that caused major damage.   The quake was 56 kilometers from Queen Charlotte City, this is close but not too close.   In earthquakes location matters.

In 2010 and 2011 there were several earthquakes to hit Christchurch New Zealand.  The first earthquake was 40 kilometers from the centre of Christchurch and even though it had a strength of 7.1M, it was not that seriously damaging.  In February 2011 there was a 6.3M aftershock located only 8 kilometers from the core of the city.  It was the second smaller earthquake that was much more damaging because it was so much closer to the core of the city.

How much a difference is a 7.7M earthquake to the sort of Cascadia subduction zone earthquake the westcoast will see some day?   The last Cascadia earthquake on January 26th 1700 was 90 times stronger than the one that hit Haida Gwaii over the weekend.

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