Canada, Northwest Territories Quake

An outcropping of Canadian Shield in the Old T...

Image via Wikipedia

A 5.3 magnitude earthquake was felt in Canada’s Northwest territories yesterday which is a rare event. While larger quakes do happen here once in a while, like 1985, October and December each had a magnitude 6.8 and there was another 6 plus quake in 1988 5+ quakes happen here every cuple of years and for a little while there are more after the 6+’s.

All of these quakes are close to the surface, with just a few deeper than 20 km. There are no large faults but the area is a folded mountain zone being created by the collision of the North American Plate and the Pacific Plate. The collision between the two plates is still happening so the mountaisn are still building and so the quakes keep happening.

This is the highlands above the McKenzie Valley, a sparsely populated landscape very cold in the winters and inhabited by brown bears and elk/caribou. There is also glacial relief happening which could be contributing to the quake activity. The quake was reported as felt 1600 km away. Whether this was fanciful thinking or actual is another thing. The high mountains are all folded, with many faults and fractures. If the report of feeling it was to the east  would be more inclined to believe it as that way is the Canadian Shield, an old dense rock that transmits tremors much better than the broken folded mountains of British Columbia.

Still it’s the largest quake in Canada since the north Cascadia quake and in the region it happened it’s noteworthy. Connections will inevitably be drawn by some to the Cascadia fault zone, both being in Canada but they are on opposite sides and opposite ends of a range of mountains. With this zone so far north of the Cascadia zone pressures exerted here would not be directly transmitted to the Cascadia fault and any earthquake storm that might have a chance to push the transferred pressure would have to make many twists and turns to get there.

Yes the same basic movement of the plate westward would be the force behind both zones but there is no real connection. This zone does have a common link to the Alaska Peninsula zones via Fairbanks but no direct connection to the southern BC zones that affect Cascadia. So if you are from southern BC this is not an indicator for you to be worried. If you are a brown bear in northern BC the this earthquake may have waken you from your nap.


About echlinm

Computer Programmer/Systems Analyst/Hacker S31
This entry was posted in Earth Science, Earthquake and tagged , , , , , , , . Bookmark the permalink.

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