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

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Employee at Shoppers Drug Mart in Mission tests positive for COVID-19

One of five BC locations to have positive tests last week for the Loblaws chain

Mission woman wins $50,000 on a scratch ticket

Colleen Monds was speechless after realizing she won on a Casino Royale ticket

Police seek assistance locating missing Hope teen, last seen near Agassiz

RCMP say Jada Charlie-Carlson was last seen Monday in the 61000 block of Lougheed Highway

Green Party announces candidate for Maple Ridge-Mission

Trenholm running for first time in a closely contested riding

Air quality across the Lower Mainland could worsen slightly

AQ health index could see ‘low risk’ gravitate into ‘moderate risk’ from Vancouver to Hope

Orange Shirt Society launches first textbook on residential school history

Phyllis Webstad and Joan Sorley worked on the 156-page book to help educate students

U.S. boater fined $1,000 for violation of Quarantine Act

49-year-old man entered Canada to visit girlfriend in Surrey

More sex abuse charges laid against B.C. man who went by ‘Doctor Ray Gaglardi’

Investigators now focussing efforts on alleged victims within the Glad Tidings Church community

B.C. VOTES 2020: Businesses now owe $6 billion in deferred tax payments

COVID-19 relief from remittance to province ends with September

Long-term care study credits fewer COVID deaths in B.C. than Ont. to funding, policy

The study was published Wednesday in the Canadian Medical Association Journal

Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

NDP asks Elections BC to investigate Liberal voter fraud allegations in Surrey-Fleetwood

Campaign organizer for MLA candidate Garry Thind allegedly solicited personal information from voters to request mail-in ballots over the internet, NDP says

Mobile hair salon rolls into Fraser Valley

Prime Real Estate Salon is a fully functioning hairdressing business located entirely within a truck

Most Read