Earlier this month 400 tremors, which were not felt, were documented within a 24 hour period, with most of them located just south of Victoria. (Map from John Cassidy/Twitter)

Island moves four to five millimetres away from mainland

Southern Vancouver Island shifts due to tiny tremors

Tiny tremors in recent weeks are causing southern Vancouver Island to shift roughly four to five millimetres away from the Lower Mainland, says a local expert.

According to John Cassidy, an earthquake seismologist with Natural Resources Canada, the shift occurs when the Juan de Fuca plate sinks under the overlying North American plate, which Vancouver Island is on, causing them to lock together and store energy.

When the North American plate moves and releases some pressure in what is known as an episodic tremor and slip process, energy is released in the form of tiny tremors and causes the shift to the west. “As the ocean plate continues to be pushed towards us and it hits North America, it causes a buckling and a squeezing,” Cassidy said. “We have thousands and thousands of these little tiny tremors that nobody feels and they happen at the same time. When we record these tremors that we can easily locate, that’s the same time that Vancouver Island changes direction and moves to the west.”

RELATED: More than 150 tremors hit Vancouver Island in last 24 hours

Roughly 20 years ago, new GPS instruments were deployed and showed seismologists how the surface of the earth was moving.

What researchers found was that south Vancouver Island was slowly moving east roughly one centimetre towards the Lower Mainland each year. But as scientists began to process the data, they found it wasn’t moving smoothly.

Similar to a pin ball machine in which the ball bounces from one side of the machine to the other, scientists found southern Vancouver Island was also doing the same. Every 14 to 16 months over a two to three week period tiny tremors cause southern Vancouver Island to change direction and move roughly four to five millimetres to the west, away from the Lower Mainland, before continuing to move east again.

Cassidy said the information has helped researchers map out the parts of the subduction fault that are locked and where energy is being stored for future earthquakes. It allows them to estimate ground shaking, but doesn’t allow them to predict when an earthquake could take place.

Northern Vancouver Island will also go through a similar process within the next couple of months, changing directions and moving to the west, before continuing to move east.

While Cassidy said the shift is not out of the ordinary, it is a reminder to Island residents that they live in an active earthquake zone.

“We’re just a little bit farther from Vancouver for a few weeks,” he joked, adding the shift has also been seen in other parts of the world as well.

“It’s been scientifically useful, but for all of us, it’s a good reminder that this is an active earthquake zone.”


Like us on Facebook and follow us on Twitter

kendra.wong@goldstreamgazette.com

Just Posted

VIDEO: Kitten rescued from under school bus in Duncan

School staff have affectionately called kitten “Axle”

Lake Flashback: Sandy Berry is featured as our look back at Decembers past continues

WFI got a Christmas gift in 1978, but by 1993, some residents were in need of a police warning

Ship sinking in Cowichan Bay

As heavy rains fall and winds kick up waves, a ship was… Continue reading

VIDEO: Celebrate New Year’s Eve ‘Youbou style’ with Eagle Eyes, Joint Chiefs at this big bash

Music, friends, dancing, and fun: sounds like a great way to welcome 2019 for Cowichan Lake folks

Baby, it’s nasty outside: wind and rain will continue across Vancouver Island

Police warn drivers and pedestrians to use precaution during expected rain and winds

Omar Khadr wants changes to bail conditions

‘My life is held in suspension’, says the former Guantanamo Bay detainee

Coming up in Cowichan: Celebrate the second floor with the HUB

Celebrate the second floor this weekend at HUB at Cowichan Station Dec.… Continue reading

Sissons scores OT winner as Predators beat Canucks 4-3

VIDEO: Vancouver battles back to earn single point in Nashville

High streamflow advisory in effect across the Island

River Forecast Centre issues advisory as Pacific storms batter the coast

Trapped Vancouver Island crash survivor celebrates second chance at life

“Life is good now. It’s good to be alive.”

Lions announce seven members of coaching staff not coming back for 2019

The operational moves come two days after the Lions announced DeVone Claybrooks as the team’s new head coach

$12K awarded to atheist family who oppose Christmas, Hanukkah in B.C. classroom

Gary Mangel,May Yasue said holidays, Remembrance Day and Valentine’s Day not appropriate in preschool

Coach accused of sexual assault says apology letter was misinterpreted

Dave Brubaker has pleaded not guilty to one count of sexual assault and one count of invitation to sexual touching

Give the gift of nature this holiday season

Please don’t be mad, but I bought you a moose

Most Read