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

Get local stories you won't find anywhere else right to your inbox.
Sign up here

 

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

Provincial COVID-19 data can now be used for B.C. to prepare for a second wave

In the past week, B.C. has seen a slight spike in daily test-positive case counts

RDCK to implement new emergency alert notification system

System also includes sends alerts for water advisories

From baseball stars to forest fires: Southeast Fire Centre water bomber has an interesting past

Tanker 489 is stationed in Castlegar this year, but in the 1960s it belonged to the L.A. Dodgers.

Traffic finally eases along Arrow Lakes ferry routes

Motorists were stuck for up to six hours in ferry lineups over the weekend

Shoppers Drug Mart launches in-store virtual service at several B.C. stores

The service is now available in 12 rural B.C. communities and will expand province-wide in August

Islanders want BC Ferries to follow order that lets residents board before tourists

For ferry-dependent communities, ferries are often the sole practical lifeline to work, school or medical appointments.

Beverly Hills 90210 star’s family selling Vancouver Island Beach Resort

You can own Jason Priestley’s Terrace Beach Resort in Ucluelet for less than $5 million

Genetic detectives begin work to trace spread of COVID-19 in Canada

The kinds of genetic technology being used for this project did not exist when SARS hit Canada in 2003

Sports fishers protest Fraser River Chinook closures

Public Fishery Alliance wants hatchery fish open for harvest

Amber Alert for two Quebec girls cancelled after bodies found

Romy Carpentier, 6, Norah Carpentier, 11, and their father, Martin Carpentier, missing since Wednesday

B.C. man prepares to be first to receive double-hand transplant in Canada

After the surgery, transplant patients face a long recovery

Grocers appear before MPs to explain decision to cut pandemic pay

Executives from three of Canada’s largest grocery chains have defended their decision to end temporary wage increases

Bringing support to Indigenous students and communities, while fulfilling a dream

Mitacs is a nonprofit organization that operates research and training programs

Most Read