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

In Pictures: Expression Sessions hangs ten

Wave gods smile on the 10th edition of the Haida Gwaii surf festival

Haida Gwaii Sea Cadets set sail

Some young salts joined the Remembrance Day parade in Queen Charlotte last… Continue reading

Rough seas delay Prince Rupert/Haida Gwaii ferry

Northern Expedition is expected to leave Prince Rupert for Haida Gwaii at noon on Tuesday, Nov. 13

In Pictures: Remembrance Day in Queen Charlotte

Drums, bells and bagpipes sounded across Haida Gwaii this Remembrance Day, which… Continue reading

B.C. Legions in need of young members to continue aiding veterans into the future

Lest we forget what thousands of men and women did to fight for Canada’s freedoms – but without new membership, many Legion chapters face dwindling numbers

Throw a snowball to help kids at BC Children’s Hospital

Effort will raise money for sick kids over the holidays

Expect no quick end to Canada-wide cannabis shortages, producers warn

Provinces including British Columbia, Alberta have all reported varying degrees of shortages

Want to buy your first home? Move to Kamloops or Prince George

Kamloops, Prince George, Campbell River and Langford are the only other markets in the study without gaps between required and actual income in owning a home.

Seniors in care homes may not get referendum ballots in the mail: Seniors Advocate

Voters list was established in May 2017, so if they moved into a care home since then….

Feds give $2 million for anti-extremism programs in B.C.

Public Safety Minister Mike Farnworth said supporting efforts locally is key to prevention

Should the legal age for cannabis be increased to 21?

B.C. residents have a more mellow attitude to the age limit for pot – but 23 per cent want the legal age increased

Expect ride hailing in B.C. by 2020, Premier Horgan says

Taxi-style insurance option needed for part-time drivers

B.C. on track to record same number of overdose deaths as last year

128 people died of overdoses in September, bringing the total to more than 1,100 so far in 2018

Canada Post strike having ‘critical’ impact on retailers, eBay tells PM

Canada Post says it is now facing an unprecedented backlog of shipments, largely as a result of strikes

Most Read