The central-west part of Vancouver Island had over 600 “tiny tremors” last week, which were too small to be felt, according to a seismologist.
John Cassidy, an earthquake seismologist with Natural Resources Canada, says the earthquakes have been recorded along the west coast of the Island between Tofino and the Nootka Island region.
“First off, this is a really regular occurrence, it’s a regular process. It really reminds us that we live in the neck of subduction zones. We live in a region where an ocean plate is being pushed beneath Vancouver Island, Washington, Oregon, and Northern California,” Cassidy said in an interview with CHEK News.
“Every 14 to 15 months we see exactly this process happening and it happens in different areas at different times.”
Is #ETS back to start off 2023?
633 tiny tremors (not felt) have occurred during the past week on west-central #VancouverIsland between Nootka Island and #Tofino. The last ETS event in this area was in Oct. 2021.
ETS:https://t.co/M6SpDeKKSw#PNSN monitor:https://t.co/GbXdBrv4T6 pic.twitter.com/YCGRpD5sMx
— John Cassidy (@earthquakeguy) January 3, 2023
In March 2022, Cassidy says there was a similar event on the South Island, where there were around 6,000 unfelt tremors, and before that a similar series occurred in Washington, and Oregon before that.
“They’re happening almost all the time throughout what we call a subduction zone,” Cassidy said. “It doesn’t tell us that anything’s about to happen…But it really reminds us that this is an active subduction zone.”
While it’s too early to tell, Cassidy says these tremors may be an episodic tremor and slip event.
“There are two things that tell us if there is one of these episodic tremor and slip events. One is the tremors themselves that are so small but easily located, and what we’re looking for is several days of tremors,” Cassidy said.
“The other part of it is what’s associated with the ETS events is that parts of Vancouver Island will slip. Normally we’re moving very slowly towards the mainland, at several millimetres per year, about a centimetre per year, but what happens during these ETS events is that we change direction and move backwards towards the ocean towards Japan, in fact, by several millimetres.”
Cassidy says the second piece usually takes longer to confirm since the actual movement is so small.
While these tremors can’t be used to say the “big one” is on its way, Cassidy says it serves as an important reminder to be prepared for if it eventually comes.
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“As individuals having an earthquake kit, having a plan, knowing what to do when the shaking begins is really important” Cassidy said.
“There are so many very simple things that we can do to be ready and prepared and the earthquake kit is a part of it. Having the water, having the food, having a flashlight and slippers under your bed so that if there’s an earthquake in the night you can move around your house and not be stepping on glass or broken objects.”
He says the other key piece is knowing what to do when there is shaking happening.
“Knowing the drop cover, and hold on. If you feel shaking, get under a table as we practice during ShakeOut each year, getting under a table and holding on to that table or desk or chair so that it doesn’t move away from you during an earthquake,” Cassidy said.
“During very strong earthquakes, not only are things falling over and you’re trying to protect yourself from those objects, but during our strong earthquakes items will move across the room, like tables and desks, so you want to hold on to it so it doesn’t move away from you.”