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

A mind of their own

I was talking to my mom this week, who remarked that kids… Continue reading

Get your cowbells, the Cowboy Concert will be in 100 Mile House on Feb. 16

The matinee show is sold out but tickets are still available for the evening show

Small programs can make a big difference

At the 100 Mile Free Press, we’re currently working on completing this… Continue reading

Snowarama coming to Green Lake area

Poker run, 50/50 draw and an open house at the snowmobile club

Mermen calendar targets ‘toxic masculinity,’ raises big money for charities

Newfoundland and Labrador Beard and Moustache Club gave a cheque for more than $202,000 to Violence Prevention NL

Minister says plans to fight poverty, climate change, focus of B.C. budget

The NDP said in its throne speech last week that affordability will be the hallmark of its initiatives

UPDATED: ‘Violent’ B.C. man back in custody after Alberta arrest

Prince George man with ties to Vernon was being sought by police

After a week away, SNC-Lavalin questions await MPs returning to Parliament

Two have resigned already: Jody Wilson-Raybould was veterans affairs minister and Gerald Butts was Trudeau’s principal secretary

‘How did we get here?’: B.C. mom of transplant recipient worries about measles outbreaks

Addison, 7, cannot get a live vaccine because she has a heart transplant

Poverty coalition has high hopes for B.C. poverty reduction strategy

Funding allocation expected to be released with 2019 budget

Chanel: Iconic couturier Karl Lagerfeld has died

He spent virtually his entire career at luxury labels catering to the very wealthy

Interior Health on high alert for possible measles cases

No reports of the disease yet, but regular travel to the Coast could bring measles to the Interior

Lost a ring? This B.C. man will find it for you

Chris Turner founded The Ring Finders, an international directory of metal detector hobbyists

Most Read