There have been more than 150 tremors during the past 24 hours stretching from the Alberni Valley to Cowichan. (Photo John Cassidy and pnsn.org)

There have been more than 150 tremors during the past 24 hours stretching from the Alberni Valley to Cowichan. (Photo John Cassidy and pnsn.org)

More than 150 tremors hit Vancouver Island in last 24 hours

Seismologists monitor to see if pressure will be added to major fault

More than 150 tremors have hit Vancouver Island in the last 24 hours, and seismologists are monitoring the situation to see if it turns into an Episodic Tremor and Slip event.

Vancouver Island is normally moving toward the Lower Mainland at a rate of about one centimetre per year.

“Ferry fares keep going up but the distance is actually getting a little bit shorter,” jokes John Cassidy, seismologist with the Geological Survey of Canada.

But every 14 months or so there is a Tremor and Slip event – a discovery made by two local scientists Gary Rogers and Herb Dragert – when Vancouver Island slips backwards a few millimetres towards Japan. Seismic recording instruments show Victoria moving in one direction and then changing direction for about two weeks during these episodes. These events add pressure to the locked Cascadian Subduction Zone fault.

“It involves tiny tremors that we can record. They are not earthquakes. People don’t feel these shaking events. But we can easily record them over many seismic stations at the same time,” said Cassidy. “It looks like a train or a rumbling.”

You can see the energy building up slowly and then dropping off slowly, says Cassidy. It’s not a typical earthquake signature. It’s more of a rumbling vibration sort of signal.

The tremors are recorded and mapped out, to show where the slip is taking place. It helps to identify the locked portion of the subduction fault where all the energy is being stored for future earthquakes.

“This is a really important piece of information to help us understand the subduction zone where these big earthquakes are more likely to occur,” said Cassidy. “It doesn’t help us predict when an earthquake will occur, though.”

Due to the fact that Episodic Tremor and Slip events give a slight nudge to a locked fault, it is a period of slightly higher hazard but Cassidy assures that it is not a huge change.

“It is similar to driving in slightly heavier traffic than you normally would. There might be slightly more risk,” said Cassidy. “Bottom line is that we live in a subduction zone where earthquakes can happen at any time. These tremors are a reminder to us that we do live in an active zone and to be prepared.”

It will take a week of monitoring the situation to see if a slip takes place.


 

keri.coles@oakbaynews.com

Follow us on Instagram
Like us on Facebook and follow us on Twitter.

EarthquakeTremors

Just Posted

Surrey council chambers. (File photo)
Surrey council endorses ‘public engagement’ strategy

Council approves ‘Public Engagement Strategy and Toolkit,’ and a ‘Big Vision, Bold Moves’ transportation public engagement plan

Surrey City Hall. (File photo)
Surrey council approves $7.3 million contract for street paving projects

City council awarded Lafarge Canada Inc. $7,326,667.95 for 15 road projects in North Surrey and one in South Surrey

Surrey city Councillor Brenda Locke. (File photo)
Locke seeks breakdown on what Surreyites get for taxes paid to Metro Vancouver

Surrey councillor presented motion to council Monday asking city staff to do a cost/benefit analysis

TEASER PHOTO ONLY
SURREY NOW & THEN: Little Theatre’s 59-year history ends with big plans for move to Langley

A former church, the theatre building/property has sold for close to $900,000

Old trucks are seen in the yard at the B.C. Vintage Truck Museum in Cloverdale June 14, 2021. The Museum is reopening June 19 after a seven-month COVID closure. (Photo: Malin Jordan)
Cloverdale’s truck museum to reopen

B.C. Vintage Truck Museum set to open its doors June 19

Canadian Prime Minister Justin Trudeau participates in a plenary session at the G7 Summit in Carbis Bay, England on Friday June 11, 2021. THE CANADIAN PRESS/Adrian Wyld
Canada donating 13M surplus COVID-19 vaccine doses to poor countries

Trudeau says the government will pay for 87 million shots to be distributed to poor countries

Montreal Canadiens goaltender Carey Price (31) is scored on by Vegas Golden Knights defenseman Alec Martinez, not pictured, during the second period in Game 1 of an NHL hockey Stanley Cup semifinal playoff series Monday, June 14, 2021, in Las Vegas. (AP Photo/John Locher)
Habs fall 4-1 to Vegas Golden Knights in Game 1 of NHL semifinal series

Match was Montreal’s first game outside of Canada in 2021

Kelowna-Lake Country MLA Norm Letnick, assistant deputy speaker at the B.C. legislature, presides over committee discussions. The legislature is completing its delayed spring session this week, with most MLAs participating by video conference. (Hansard TV)
B.C.’s daily COVID-19 infections dip below 100 over weekend

Only 68 new cases recorded Monday, four additional deaths

Robert Nelson, 35, died after being stabbed at a homeless camp in Abbotsford on April 7 of this year.
Mom pleads for information about son’s killing at Abbotsford homeless camp

Robert Nelson, 35, described as ‘man who stood for justice, honour, respect’

The BC Ferries website went down for a short while Monday morning following a provincial announcement that recreational travel between health authorities can resume Tuesday. (Black Press Media file photo)
BC Ferries’ website crashes in wake of provincial reopening announcement

Website back up now, recreational travel between health regions to resume as of Tuesday

The Kamloops Indian Residential School is photographed using a drone in Kamloops, B.C., Monday, June, 14, 2021. The remains of 215 children were discovered buried near the former school earlier this month. THE CANADIAN PRESS/Jonathan Hayward
Communities grapple with what to do with former residential and day schools

Some tear them down as a tool to help healing, others repurpose them as tools for moving forward

Police arrest the suspect in an attempted armed bank robbery on June 2 at the Scotiabank at Gladwin Road and South Fraser Way in Abbotsford. (Photo by Garry Amyot)
Abbotsford bank robbery suspect who was stopped by customers faces more charges

Neil Simpson now faces total of eight charges, up from the initial two

FILE – Provincial health officer Dr. Bonnie Henry talks about B.C.’s plan to restart the province during a press conference at Legislature in Victoria, Tuesday, May 25, 2021. THE CANADIAN PRESS/Chad Hipolito
B.C. watching U.K.’s COVID struggles but don’t think province will see similar pitfalls

Studies show that one dose of vaccine is only 33 per cent effective in preventing B.1.617.2 spread

RCMP Const. Shelby Patton is shown in this undated handout photo. RCMP say that Patton was hit by an allegedly stolen truck that he had pulled over on Saturday morning in Wolseley, east of Regina. THE CANADIAN PRESS/HO, RCMP
Pair charged in Saskatchewan Mountie’s death make first court appearance

Const. Shelby Patton was hit by an allegedly stolen truck that he had pulled over Saturday morning

Most Read