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

Two fires of note burning in Southeast Fire Centre

As of Saturday afternoon there were more than 20 fires burning in the Southeast Fire Centre.

‘Farm the Kootenays’ creates supportive community

Helping hobbyists and serious producers alike, the Facebook group has grown to nearly 12,000 members

Who will fill the Greyhound void in the Kootenays?

Minister Conroy, MLA for Kootenay West sees opportunity for local operators

Equipment lost in arson at Greenwood landfill

The cost of replacing equipment is expected to be significant.

What you see …

If you have a recent photo to share email editor@trailtimes.ca

All-Indigenous teams break new ground, making BC Games history

This is the first time there have been dedicated Indigenous teams at the BC Summer Games

Lower Mainland teams battle for baseball gold at BC Games

Vancouver Coastal squeaked out a 3-2 win against Fraser Valley

The Northern Secwepemc te Qelmucw people signed an agreement-in-principle with the B.C. government

The signing ceremony, at the Eliza Archie Memorial School, was 25 years in the making

Ping-pong balls of fire dropped to merge two B.C. wildfires

The merger is considered successful by BC Wildfire Services

Canada to resettle dozens of White Helmets and their families from Syria

There are fears the volunteers would become a target for government troops

Francesco Molinari wins British Open at Carnoustie

It is his first win at a major and the first by an Italian

Government sets full-time salary range for Justin Trudeau’s nanny

At its top range, the order works out to a rate of $21.79 per hour, assuming a 40-hour work week

ZONE 1: Hannah Tracey looks to mom as role model while at BC Games

‘She has believed in me when I couldn’t believe in myself,’ Tracey said at BC Summer Games in Cowichan

Recovery high schools could help teens before addiction takes hold: B.C. parents

Schools could provide mental health supports and let parents discuss their children’s drug use openly

Most Read