Vancouver woke up to its second earthquake in 10 days on Monday morning. It was also the third earthquake to occur in the region since Feb. 21. No damage has been reported, and there is no tsunami risk.
Alison Bird, an earthquake seismologist with Natural Resources Canada, spoke to The Globe and Mail about the recent quakes, and what Vancouverites should do ahead of future tremors.
Why have these earthquakes occurred so close together?
That’s simply a matter of coincidence. The earthquakes are not related. They are in the same plate, but they’re not actually that close together. One happened more shallow than the other, they didn’t happen on the same fault or anything like that. So they’re just happenstance. They happened together.
Could this be a predictor for more earthquakes?
It’s highly unlikely that these either these were foreshocks. Foreshocks are incredibly rare, and they also didn’t occur on any major faults. So it would be unlikely that these would lead to major events, but they are a good reminder. We will have large events in our future. We just simply don’t know when.
If you have a lot of earthquakes in close sequence, can they have an impact on one another?
Earthquakes can have an impact on one another. These that we’ve recently experienced do not, and they’re probably not an indication that larger earthquakes will occur, but certainly when you have something this size, you can expect smaller earthquakes to happen in the vicinity, sort of as aftershocks.
What intensity would cause damage to Vancouver or Vancouver Island?
So, you mentioned the word intensity. It’s different than magnitude. So magnitude is the size of the earthquake itself. Intensity is the strength of shaking, so how people experience it. Generally speaking, the closer you are to the earthquake, the more you will feel it. So that’s why the earthquake early warning system is triggered for magnitude 5 and intensity 4. That’s the level at which things can start to fall over and people could end up getting injured.
What would this sort of damage look like?
We start to alert people at that level when it’s just interior contents: Things falling off shelves, maybe a shelving unit falling over. Structural damage happens at higher intensities, higher magnitudes. So then you start to see things like chimneys failing and toppling. But major structural damage is actually quite rare. People assume it’s going to be like the Hollywood scenario where it’s complete and utter death and destruction. And it’s not, especially in North American architecture, we’ve got a fairly good building code.
I know you mentioned earlier that it’s important to remember that bigger earthquakes can come. What should Vancouverites do ahead of those earthquakes?
Well, certainly I encourage people to be as prepared as they can be. The more prepared you are for the event, the safer you are during the event and the more comfortable you’re going to be after. So I encourage people to have their emergency kit. I encourage it to be two weeks or more if you can. Have a plan with your family, have a plan with your colleagues. Going around your home and looking for what might be caused to fall over or anything like that. And then, I really encouraged people just put a pair of sturdy shoes and a flashlight under their bed.
Is there anything else that you would like to say?
We do have earthquake early warnings. I encourage people if they get the alert on their phone or TV or radio, please do heed it. Please do drop, cover and hold on, and do practise that.
This interview has been condensed for length.