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

UFV students raise money to keep ‘nicest’ person in Abbotsford

Foreign student struggles to pay for schooling after Trump withdrawal from Iran deal

Jordyn Huitema wins Canada Soccer Youth International Player of the Year award.

The Chilliwack FC grad enjoyed a fantastic season representing her country in international play.

DFO confirms that investigation of fish habitat destruction in the Fraser River is underway

Conservation and Protection reps ordered Herrling and Carey Island owners to take corrective action

Petition against Bridal Falls gondola floated by Chilliwack man

Some say the gondola could close off a huge swath of recreational area above Bridal Falls

Controversial Chilliwack trustee won’t be allowed in schools

Barry Neufeld calls vote to leave him off liaison list ‘workplace discrimination’

Man caught on camera allegedly trying to defraud ICBC

Auto-insurer warns B.C. drivers to record info after crashes

2,000 Canadians died of an overdose in first 6 months of the year

New data from the Public Health Agency of Canada shows the crisis is not subsiding

Teenager Alphonso Davies wins Canadian Men’s Soccer Player for the Year Award

Derek Cornelius and Chilliwack native, Jordyn Huitema were named Canadian Youth International Players of the Year

B.C. teen MMA fighter shows heart

Young Unity MMA competitors bring home Ws

Torched-SUV victim ‘had the purest heart,’ says sister

Family of teen found in burned SUV in Surrey appeals for justice

Another B.C. city votes to ban single-use plastic bags

First six months of proposed ban would focus on education, not enforcement

UK Prime Minister Theresa May wins party no-confidence vote, but troubles remain

May won the vote of 317 Conservative legislators with a 200-117 tally

B.C. trustee’s anti-LGBTQ comments got him barred from schools

Barry Neufeld calls vote to leave him off liaison list ‘workplace discrimination’

Most Read