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

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

Just Posted

A peacock struts by a pair of lamb siblings at the Beacon Hill Children’s Farm, which remains closed to the public. (Don Descoteau/News Staff)
VIDEO: Victoria petting zoo optimistic about future after 13 months closed

Public helps non-profit Beacon Hill Children’s Farm with nearly $100,000 influx

Island Health declared a COVID-19 outbreak in two houses at the Mount St. Mary long-term care home on Wednesday. (Photo courtesy of Google Earth)
Island Health declares outbreak at Victoria long-term care home

Resident, staff member test positive for COVID-19 at Mount St. Mary facility

Vancouver Island Connector and Tofino Bus is putting a 41-passenger electric bus through its paces in a three-month trial run between Nanaimo and Victoria. (Photo submitted)
Electric bus on trial run serving Victoria-to-Nanaimo route

Vancouver Island Connector and Tofino Bus trying out 41-seat electric coach for three months

Greater Victoria Crime Stoppers is helping Saanich police locate a suspect who allegedly stole an iPhone from a building in the 3100-block of Foul Bay Road on April 7. (Image via the Greater Victoria Crime Stoppers)
Saanich police seek suspect in cell phone theft

White iPhone XR reported stolen from building on Foul Bay Road April 7

Victoria police are looking for a 38-year-old man after he allegedly assaulted and choked a missing 15-year-old victim in Beacon Hill Park Tuesday night. (Black Press Media file photo)
15-year-old choked in Beacon Hill tent, Victoria police assaulted while intervening

Police searching for 38-year-old suspect, two officers injured in altercation with park residents

A large crowd protested against COVID-19 measures at Sunset Beach in Vancouver on Tuesday, April 20, 2021. (Snapchat)
VIDEO: Large, police-patrolled crowds gather at Vancouver beach for COVID protests

Vancouver police said they patrolled the area and monitored all gatherings

(Black Press Media file photo)
POLL: Have rising prices caused you to give up hope of buying a home?

Do you have a spare 50 grand or so kicking around (have… Continue reading

Anyone with information on any of these individuals is asked to call 1-800-222-TIPS (8477) or visit the website victoriacrimestoppers.ca for more information.
Greater Victoria Crime Stoppers wanted list for the week of April 20

Greater Victoria Crime Stoppers is seeking the public’s help in locating the… Continue reading

A teacher-librarian in Nanaimo was fired in 2019 for checking out an age-inappropriate graphic novel to a student. The discipline agreement was published Wednesday, April 21. (News Bulletin file photo)
Nanaimo teacher-librarian fired for checking out too-graphic graphic novel to student

Teacher had been previously disciplined and suspended on two occasions

Aria Pendak Jefferson cuddles ChiChi, the family cat that ran away two years ago in Ucluelet. The feline was missing until Courtney Johnson and Barry Edge discovered her in the parking lot of the Canadian Princess earlier this month. Aria and her parents were reunited with ChiChi in a parking lot in Port Alberni. (SUSAN QUINN/ Alberni Valley News)
An Island girl’s wish is answered as her cat came back

Courtenay family reunited with cat that went missing in Ucluelet in 2019

FILE – The Instagram app is shown on an iPhone in Toronto on Monday, March 19, 2018. THE CANADIAN PRESS/Graeme Roy
Judge acquits B.C. teen boy ‘set up’ on sex assault charge based on Instagram messages

The girl and her friends did not have ‘good intentions’ towards the accused, judge says

Kai Palkeinen recently helped a car stuck on the riverbed near the Big Eddy Bridge. While the car could not be saved, some of the driver’s belongings were. It’s common for vehicles to get stuck in the area due to significantly changing river levels from Revelstoke Dam. (Photo by Kai Palkeinen)
“I just sank a car’: Revelstoke resident tries to save vehicle from the Columbia River

Although it’s not permitted, the riverbed near the city is popular for off roading

Meng Wanzhou, chief financial officer of Huawei, walks down the street with an acquaintance after leaving B.C. Supreme Court during a lunch break at her extradition hearing, in Vancouver, B.C., Thursday, April 1, 2021. A judge is scheduled to release her decision today on a request to delay the final leg of hearings in Meng Wanzhou’s extradition case. THE CANADIAN PRESS/Rich Lam
B.C. judge grants Meng Wanzhou’s request to delay extradition hearings

Lawyers for Canada’s attorney general had argued there is no justification to delay proceedings in the case

B.C. Premier John Horgan announces travel restrictions between the province’s regional health authorities at the legislature, April 19, 2021. (B.C. government photo)
B.C. sees 862 more COVID-19 cases Wednesday, seven deaths

Recreational travel restrictions set to begin Friday

Most Read