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)

Island moves four to five millimetres away from mainland

Southern Vancouver Island shifts due to tiny tremors

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

Just Posted

Beauty Day spreads ‘brightness’ at Our Place

Volunteer hairdressers, estheticians, even a tarot card reader took part in the Victoria event

Victoria Guard Commander leads group of snowmen after ceremony cancelled

Lt.-Cmdr. Michael Irwin wasn’t going to let a bit of snow strip him of his duties

Number of adults living with parents has doubled since 1995

9 per cent of the adult population living with one or more parent

VIDEO: Canada’s flag turns 54 today

The maple leaf design by George Stanley made its first appearance Feb. 15, 1965

Eight cases of measles confirmed in Vancouver outbreak

Coastal Health official say the cases stem from the French-language Ecole Jules Verne Secondary

Plecas won’t run in next election if B.C. legislature oversight reforms pass

B.C. Speaker and Abbotsford South MLA says he feels ‘great sympathy’ for Jody Wilson-Raybould

Workshop with ‘accent reduction’ training cancelled at UBC

The workshop was cancelled the same day as an email was sent out to international students

Former B.C. premier Gordon Campbell accused of sexual touching

Accuser went to police, interviewed by Britian’s Daily Telegraph

Man in Vancouver Island hotel shooting pleads guilty to second-degree murder

Brandon Tyler Woody, from Victoria, to be sentenced in late March in B.C. Supreme Court

Judge rules Abbotsford home must be sold after son tries to evict mom

Mom to get back down payment and initial expenses

Trump officially declares national emergency to build border wall

President plans to siphon billions from federal military construction and counterdrug efforts

Snow turns to slush, rain as it warms up across B.C.’s south coast

Some areas are already covered by more than half a metre of snow following three separate storms

Most Read