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

Fort St. James businesses get into the Christmas spirit with decorating contest

Northland Automotive Ltd. won first place in Fort St. James Chamber of… Continue reading

Couple selling fake jewelry in Fraser Lake, say RCMP

A man and woman have been defrauding local residents, offering fake jewelry for sale

Gitxsan forming cross-sector salmon management team

Nation again declares closure of fishery in territory for 2019

Editorial: The Speaker shouldn’t be an MLA

Time to re-evaluate the Speaker position

Man caught on camera allegedly trying to defraud ICBC

Auto-insurer warns B.C. drivers to record info after crashes

Second Canadian missing in China after questioning by authorities

Michael Spavor, founder of a non-profit that organizes cultural-exchange trips to North Korea, “is presently missing in China”

Warning issued as forecast calls for 20-foot waves in Tofino

Dangerous waves, strong currents and upper-shoreline flooding expected for Tofino-Ucluelet area

An 800-pound pig named Theodore needs a forever home, B.C. society says

‘Theodore is not destined to be somebody’s bacon’

Teenager Alphonso Davies wins Canadian Men’s Soccer Player for the Year Award

Derek Cornelius and Chilliwack native, Jordyn Huitema were named Canadian Youth International Players of the Year

B.C. teen MMA fighter shows heart

Young Unity MMA competitors bring home Ws

2,000 Canadians died of an overdose in first 6 months of the year

New data from the Public Health Agency of Canada shows the crisis is not subsiding

Another B.C. city votes to ban single-use plastic bags

First six months of proposed ban would focus on education, not enforcement

UK Prime Minister Theresa May wins party no-confidence vote, but troubles remain

May won the vote of 317 Conservative legislators with a 200-117 tally

Most Read