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BRITISH COLUMBIA | Earthquake Update

Another earthquake in B.C., breaking down this latest rumble

Digital writers

Thursday, November 1, 2018, 7:56 PM - Another earthquake was measured west of Vancouver Island on October 31st, just shy of a magnitude 5.0 on the Richter scale. Is it another earthquake related to the more powerful episodes back in October?


  • Magnitude 4.9
  • Depth: 10 km
  • 208 km southwest of Port Hardy, B.C.

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How many earthquakes do you think have occurred in British Columbia over the past month? 10? 20? 50? We've entered quite a tectonically active period.

When reviewing the data, over 80 earthquakes have been measured by sensitive seismometers, but only a couple have been felt. That's the reality of the plate tectonics around British Columbia, with major plate boundaries being offshore.

The earthquake on the evening of October 31st is a distant cousin of the recent uptick in earthquake activity along a specific fault line, not associated with the Cascadia subduction zone. This was likely an aftershock on the series of greater than magnitude 6.0 earthquakes located on the Sovanco fault. This specific transform fault boundary moves by plates sliding in opposite directions. In this case, the motion is related to the movement of the Explorer and Pacific plates.

This video below will give you a better of idea of where this geological event occurred, and will point out the subtle interactions between the plate boundaries. 

But, be aware these fault lines are quite crude – the real fault lines on the sea floor are MUCH more complicated.

This isn't the geological event that has been uncovered in relatively recent times. Have you heard of the episodic tremor and slip (ETS) event that occurs under Vancouver Island and Washington State. Get caught up to speed, here:


No. But, The 'big one' may happen 5 minutes from now, 5 years, or it could be well over 100 years away. From a preparedness standpoint, expecting the earthquake sooner, rather than later will ensure we're ready to act when the inevitable big shake occurs. A mega-thrust earthquake is one that features a disastrous magnitude 9.0 or greater energy release, but another likely scenario is a weaker, more shallow earthquake under Vancouver Island, or even the Lower Mainland. 

This could pose devastating consequences to life and property as well.  

How much more energy released with a mega-thrust earthquake vs. the series of powerful earthquakes that most recently rattled went of Vancouver Island? 

The energy release difference is STAGGERING, as it's calculated that nearly 2000 times more energy would be released from a mega-thrust earthquake than the more recent earthquakes in the 6-magnitude range. This isn't meant to fear monger, but rather just to illustrate the absolute power of these earthquakes that can occur deep under the subduction zone. 


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