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)

Tiny tremors causing Vancouver Island to move away from B.C. mainland

When the North American plate moves, energy is released and causes a shift to the west

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

 

Southern Vancouver Island has shifted four to five millimetres away from the mainland due to a number of recent tiny tremors. (Pixabay stock photo)

Just Posted

Surrey Mounties investigate drive-by shooting in Fleetwood

It happened Monday afternoon in the 8000-block of 153A Street. Police say no victim has been located.

18-year-old to hospital after shots fired in White Rock

Police investigating early-morning incident

UPDATE: White Rock RCMP unaffected by Surrey’s choice of police force, city says

Mayor Darryl Walker to meet with RCMP Staff Sgt. Daryl Creighton

PHOTOS: White Rock Remembrance Day ceremony

Residents gather to pay respect Canada’s fallen soldiers

VIDEO: Marvel Comics’ Stan Lee dies

Marvel co-creator was well-known for making cameo appearances in superhero movies

UPDATE: Man, 19, dies following shooting in Abbotsford

Victim was airlifted to hospital Monday afternoon, but died shortly afterwards

Surging Rangers beat visiting Canucks 2-1

Goalie Lundqvist ties Plante on all-time wins list

Calgary 2026 leader expects close vote in Winter Games plebiscite

Residents to choose in a non-binding vote on Tuesday whether they want city to bid on 2026 Olympics

VIDEO: Newcomer kids see first Canadian snowfall

Children arrived in Canada with their mother and two siblings last week from Eritrea

Feds dropped ball with WWI anniversary tributes: historians

Wrote one historian: ‘Other than the Vimy Ridge celebration … I think they have done a very bad job’

Sides ‘far apart’ in Canada Post talks despite mediation, says union

The lack of a breakthrough means rotating strikes will resume Tuesday

Feds’ appeal of solitary confinement decision in B.C. to be heard

Judge ruled in January that indefinite such confinement is unconstitutional, causes permanent harm

Touching note left on Lower Mainland veteran’s windshield

A veteran is hoping the writers of a note know how much he was touched by their kind words.

Most Read