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

Firefighters rescue dog as two house fires happen at the same time in Nanaimo

House extensively damaged on Uplands Drive, coach house burns down on Haliburton Street

Heat warning issued for Vancouver Island

Temperatures expected to cool down later this week

Silly boats make a splash on Nanaimo seas

Superette wins Nanaimo’s Silly Boat Regatta community fundraising event

Nanaimo lacrosse goalie scores two goals in one game

Charles Claxton leads senior A Timbermen to their fourth straight win

Redliners park their rides for charity car show in Nanaimo

The Redliners Charity Car Show continues until 3 p.m. Sunday, July 15, at Country Club Centre

VIDEO: Winners announced for Parksville sand sculpting competition

See the sculptures as they progress through the competition at Parksville Community Park

VIDEO: Firefighters putting out brush fire in East Wellington

Fire is in the area of a new development under construction near Shady Mile Way

Motorcyclist dies as fire, crash happen at the same time on Nanaimo Parkway

Young male motorcycle rider collides with one vehicle, then struck by another

Development permit approved for condo project near Millstone River

Six-storey building planned for Barsby Avenue

Short trip to car-free Sidney Spit offers camping, beaches, hikes

Sidney Spit is part of B.C.’s Gulf Islands National Park Reserve, a protected marine ecosystem

B.C. woman disappointed after family asked for ID at townhouse complex pool

Surrey woman says it’s not the first time she has experienced racial profiling at the complex

Park pipeline protesters say arrest is a ‘declaration of war’

Group behind North Thompson River Provincial Park occupation protest says arrest is ‘declaration of war’

A day of deals at Amazon, and at its rivals

Online retail giant extends annual ‘Prime Day’ promotion to 36 hours

Alert B.C. campers raise alarm and avert potential propane disaster

Salmon Arm camper lodges a complaint with Technical Safety BC after motorhome tank is over-filled.

Most Read