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.

Just Posted

Advance Voting in Revelstoke a success

The municiple election season is well underway with advance voting held on Oct. 10 and Oct. 17

Revelstoke peewee Grizzlies lose to Vernon

The Revelstoke Grizzlies Peewee Tier 3 team played Vernon on Saturday, losing… Continue reading

Fred Penner is coming to Revelstoke

The iconic children’s entertainer will be at the Revelstoke Performing Arts Centre Oct. 20

VIDEO: This is what buying legal pot in B.C. looks like

Take a look inside B.C.’s first and only legal pot shop located in Kamloops

Glimpses of Revelstoke’s past for Oct. 14

125 Years Ago: Kootenay Star, October 21, 1893 Revelstoke Station is rapidly… Continue reading

B.C. NDP retreats again on empty-home tax for urban areas

Rate reduced for all Canadians, dissident mayors to get annual meeting

Man shot to death while using Lower Mainland ATM

Police believe incident on Thursday night to be targeted

Jets score 3 late goals to beat Canucks 4-1

Winnipeg ends three-game Vancouver win streak

Okanagan water conference builds connections

Experts gathered to discuss water and fisherie sustainability objectives

Two B.C. cannabis dispensaries raided on legalization day

Port Alberni dispensaries ticketed for “unlawful sale” of cannabis

Canada not sending anyone to Saudi business summit

Sources insist Ottawa never intended to dispatch a delegation this time around

Earthquake early-warning sensors installed off coast of B.C.

The first-of-its kind warning sensors are developed by Ocean Networks Canada

VPD ordered to co-operate with B.C. police watchdog probe

According to the IIO, a court is ordering Vancouver police to co-operate with an investigation into a fatal shooting

B.C. woman looks to reduce stigma surrounding weed-smoking moms

Shannon Chiarenza, a Vancouver mom of two, started weedmama.ca to act as a guide for newcomers to legal cannabis, specifically mothers

Most Read