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

UBCO Heat teams unable to secure any wins against Mount Royal Cougars

The mens and womens volleyball and basketball teams went 0-4, but all have rematches Saturday night

Rockets held scoreless in loss against Red Deer

Rockets will look for some points in final game of road trip against Edmonton

New maintenance crew to look after Okanagan Connector

Acciona Infrastructure Maintenance Inc. will replace Argo Road Maintenance Inc. in 2019

New Lake Country arts council to request funds from district

The arts council will ask the district for $8,000 from 2019 to 2021

Your guide to winter light ups around the Okanagan

From Vernon to Summerland, with a stop in Kelowna, we’ve found some activities for you to enjoy

Trudeau offers to help Pacific islands face climate change impact

Prime Minister Justin Trudeau met with the leaders from the Pacific island nations on Saturday during the APEC Summit in Papua New Guinea

‘Toxic’ chosen as the Word of the Year by Oxford Dictionaries

Other top contenders for 2018 include ‘gaslighting’ and ‘techlash’

RCMP bust illegal B.C. cannabis lab

Marijuana may be legal but altering it using chemicals violates the Cannabis Act

Canada defeats Germany 29-10 in repechage, moves step closer to Rugby World Cup

Hong Kong needs a bonus-point win over Canada — scoring four or more tries — while denying the Canadians a bonus point

Avalanche Canada in desperate need of funding

The organization provides avalanche forecasting for an area larger than the United Kingdom

5 B.C. cities break temperature records

Parts of B.C. remain warm, at 10 C, while others feeling chilly

Hodge: The long road to recovery

Kelowna - The first week of recovery I was too consumed in pain to notice the lack of fluid.

LETTER: Plea from a Kelowna school bus driver to slow down

‘I am proud to be a school bus driver…’

Letter: Election loss in Kelowna blamed on racism

For decades I have written in the local press about racism.

Most Read