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

Highway 97 near Peachland closed due to dynamic wildfire activity

Highway 97 between Peachland and Summerland is being shut down due to wildfires

Updated: Complete list of B.C. Interior wildfire coverage

Up-to-date information on blazes happening the Kamloops Wildfire Centre

Flicked cigarette butt sparks small fire

The cigarette would have added fuel to the fire if it wasn’t for good samaritans

Okanagan Mountain Park wildfire now an estimated 400 hectares

BC Wildfire is on scene of what is being called the Good Creek blaze

Through your lens: Okanagan wildfires

Check out some of the captivating images and video from social media of the wildfires

Update: Skeleton crew to watch 1,000 hectare wildfire near Peachland overnight

Peachland - Evacuation orders have been issued for Brent Road and Highway 97 South properties

Law Creek wildfire forces evacuation alert in West Kelowna

A blaze in West Kelowna has put 198 properties on an evacuation alert

1,490 Peachland residents put on evacuation alert

The Mount Eneas wildfire has forced an evacuation alert of 596 properties

B.C. city wants pot punted from farmland

Concerned about conversion from growing food to making marijuana

Centre set up for Summerland wildfire evacuees

Summerland Emergency Support Services has processed 55 people from 16 households

On the street: Kelowna reacts to 2018 wildfires

BC Wildfire is working with local departments to battle multiple blazes near Kelowna.

World’s translators push back on forcing Trump interpreter to testify

Democrats had asked translator to testify about Trump’s lengthy conversation with Putin in Helsinki

No decision on B.C. school stabbing suspect’s mental fitness for trial

The BC Review Board could not determine whether Gabriel Klein, 21, is fit to stand trial

Update: Size of large fire near Keremeos unknown

Two significant fires are burning in the Lower Similkameen, smoke can be seen as far away as Osoyoos

Most Read