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

Investigation ramps up at home of Sukhpreet Grewal, found dead in house

Police deemed the death to be homicide Friday, Saturday brought a surge of investigators to the area

Two crashes in short span of Hwy 1 in Abbotsford holds up traffic

No serious injuries appear to have resulted, despite multiple rolls reported from one vehicle

Combined 584g of cocaine, fentanyl and meth found in Abbotsford home

Charges pending against a man and a woman after police execute search warrant on Larch St. home

Abbotsford Hopsice Society hosts third annual memorial butterfly release

Event on Saturday, July 28 at Tanglebank Gardens

Bomber to offer historic flight experience at Abbotsford Air Show

B-17 Flying Fortress offering four flights, eight people each, along with tours week of the air show

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

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

Trio overcomes adversity at the BC Games

Zone 4 girl’s 3x3 basketball team fought through injuries and conflicting schedules

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

Haida Gwaii village faces housing crisis, targets short-term rentals

Housing is tight and the village is pretty close to zero vacancy

Evacuation numbers remain at nearly 1,000 as B.C. wildfires rage on

200 firefighters and 18 helicopters were working to increase the containment of the fires

B.C. VIEWS: Unions regain control of public construction

B.C.’s 40-year battle swings back to international big labour

Most Read