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

Complex-care facility adds 60 long-term care beds

Mount Ida Mews hosts grand opening of second phase in Salmon Arm

UPDATE: One dead after crash on Highway 97A near Armstrong

Police have confirmed that one person is dead following an accident on Highway 97A Friday

Multi-vehicle collision slows traffic on Highway 1

Trans-Canada Highway reduced to single lane between Salmon Arm and Sicamous

Music program discord attributed to lack of oversight

North-Okanagan-Shuswap schools struggle to retain musical excellence amidst many challenges

National Energy Board approves Trans Mountain pipeline again

Next step includes cabinet voting on the controversial expansion

Girl heard saying ‘Help my Dad’ in suspicious radio message on Vancouver Island

Police asking for help following mysterious signals from somewhere between Comox and Sayward

Reports of rashes prompt closure of all Harrison Hot Springs pools

Public pool available after Fraser Health shut down all five mineral pools until further notice

No treatment for highly infectious measles, says doctor

10 cases of measles confirmed in Vancouver as of Friday

Two more measles cases confirmed in Vancouver

It brings the number of total cases within the city connected to the outbreak to ten

Crews continuing to clear rock north of Summerland

Site has had no movement for the past eight days

No gas in Okanagan town as lone station closed for renovations

Falkland’s Petro Canada will remain closed for renovations until March 1

Developer makes an effort to help Okanagan students left homeless after flood

U-Two developer is making an effort to help university students who were left in a lurch

Most Read