6.6 magnitude earthquake rocks Anchorage, tsunami warning issued for southern Alaska

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A 6.6 magnitude earthquake has rocked buildings in Anchorage and caused lamp posts and trees to sway, prompting people to run out of offices and seek shelter under office desks.

The U.S. Geological Survey said the earthquake Friday morning was centred about 12 kilometres north of Alaska’s largest city. 

The USGS initially said it was a 6.7 magnitude quake but reduced it to 6.6.

The National Tsunami Warning Center has issued a tsunami warning for coastal zones of southern Alaska following an earthquake that rocked buildings in downtown Anchorage.

The centre said Friday that the warning was in effect for parts of the state’s Cook Inlet and the southern Kenai peninsula.

The warning means tsunami waves are expected.

People went back inside buildings after the earthquake, but a smaller aftershock a short time later sent them running back into the streets again.

An Associated Press reporter working in downtown Anchorage saw cracks in a two-storey building after the quake. It was unclear whether there were injuries.

Anchorage lawyer Justin Capp says he was getting ready for work when he felt the shaking start. He grabbed on to the doorframe in the hallway and the door slammed into his hands, scraping his fingers and hand.

Another lawyer, Hank Graper, was driving when the quake struck. He first thought his vehicle had a flat tire, then thought it was exploding. He realized it was an earthquake after he saw traffic poles swaying.

Graper called it the most « violent » earthquake he’s experience in his 20 years in Anchorage.

The National Weather Service Seattle tweeted a tsunami warning is in effect for Cook Inlet, but it is not expected to affect Washington or B.C.

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4.2-magnitude earthquake strikes near Fort St. John

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An earthquake struck an area in northeastern B.C. close to Fort St. John on Thursday after 5 p.m. PT. 

According to the U.S. Geological Survey, the quake had a preliminary magnitude of 4.2 and the epicentre was 22.4 kilometres southeast of Fort St. John. 

People in Fort St. John, as well as Taylor, Chetwynd and Dawson Creek reported feeling the earthquake on social media, but there are currently no reports of damage.

Honn Kao, a research scientist with the Geological Survey of Canada, said early data suggests the quake had a relatively shallow depth which is likely why the quake was widely felt. 

« This is certainly an event that has been felt quite a bit by the local residents, » Kao said. « Although this is a significant event for the region I don’t think it’s going to cause significant damage. »

Hydraulic fracturing in the area

Although it is unconfirmed what caused this earthquake, Kao said the B.C. Oil and Gas Commission is investigating if the quake is related to hydraulic fracturing operations in the area. 

Hydraulic fracturing — or fracking — is when water, sand and other chemicals are injected underground at a very high pressure to fracture shale rock deep underground in order to extract natural gas. 

« They will have to link the location and time of this event to the injection operations nearby, » Kao said. 

This area of the country — western Alberta and northeast B.C. — has a high rate of fracking-induced earthquakes, according to a study from the University of Alberta.

With files from Johanna Wagstaffe

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Earthquake early-warning system installed off coast of British Columbia – National

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An earthquake early-warning system tested off British Columbia’s coast could give residents anywhere from 20 seconds to two minutes to prepare before a quake.


READ MORE:
Chances of the ‘big one’ hitting B.C. higher due to recent seismic activity: expert

The first-of-its kind warning sensors developed by Ocean Networks Canada is installed along the Cascadia subduction zone and when fully operating next March will be able to estimate location and magnitude of a megathrust earthquake.

Greig Bethel of Ocean Networks Canada, an initiative of the University of Victoria, says the system is active even as more sensors are being installed in the area to increase accuracy.

A simulated exercise was conducted Thursday in Vancouver on the 19-kilometre Canada Line stretch of the SkyTrain system, giving transit operators a chance to slow down trains and hold them at stations.

WATCH: Simulator allows Montrealers to experience 7.4 magnitude Earthquake






British Columbia is located on the Pacific Ring of Fire, an active seismic zone where thousands of mostly small earthquakes are recorded annually by sensors in the province.

Most of the quakes happen near the Cascadia subduction zone, an area where the Juan de Fuca and North American tectonic plates converge, stretching from Vancouver Island to northern California.

“Ocean Networks Canada’s earthquake early-warning technology promises a new era of earthquake preparedness that will enhance the safety of both riders and workers on the Canada Line,” says Canada Line general manager Ron Powell.


READ MORE:
Annual Great B.C. Shakeout tests your earthquake preparedness

A news release from the network says to maximize warning time, it will focus on setting sensors as close to the Cascadia subduction zone as possible and on minimizing delays in data processing, communication, and delivery of warnings.

Global Positioning System receivers will also be located with the seismic sensors to further refine the magnitude.

Earthquakes release energy that travels through the Earth as seismic waves in two forms – secondary and primary waves.

WATCH: Indonesia death toll after earthquake, tsunami rises to more than 2,000






The primary waves travel faster but the secondary waves are the cause of severe damage and ground shaking.

However, the sensors would detect primary waves to deliver alerts before the arrival of the secondary waves.

“The detection of an earthquake by many sensors can provide rapid estimates of the location and magnitude of an earthquake as it occurs,” the release says. “This information can be used to determine the estimated arrival time and intensity of ground shaking at specific locations across a region, allowing protective actions to take place before the shaking hits.”

The early-warning system can help reduce deaths, injuries and property losses, trigger trains to slow down, stop bridge and tunnel traffic, open bay doors at fire and ambulance halls, halt landings for incoming air traffic, and even allow surgeons to stop delicate procedures, the release says.

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A rumble and a boom: Earthquake rattles western Nova Scotia

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A 3.1 magnitude earthquake shook parts of western Nova Scotia on Saturday morning.

Earthquakes Canada reports that the quake occurred just off the coast in the area of Mavillette, N.S., near Meteghan, at 10:32 a.m.

Tina Helprin, who lives in Saulnierville Station, said she was sitting in her rocking chair in the kitchen when the quake happened.

« All of a sudden in the distance we heard like a rumble, like if it was going to be thunder and it rolled for like two or three seconds and then there was a loud boom and then it rolled again. It finished with another rumble of about two or three seconds, » she said.

Helprin said the entire house shook and her border collie, Cree, ran up to her, « petrified. »

« I just looked at my husband with big eyes and he looked at me right away.… I said, ‘That was not thunder.’ And he said, ‘Nope, it sure wasn’t,' » she said.

Felt from Digby to Yarmouth

Earthquakes Canada seismologist Michal Kolaj said the agency had received about 60 reports from residents between Digby and Yarmouth by Sunday morning.

« This earthquake isn’t terribly unusual for the region, » Kolaj said, adding that quakes are felt in the area every couple of years.

In 2015, a 3.6 magnitude tremor shook the area about 60 kilometres southwest of Digby on Canada Day. In 2016, a 3.0 magnitude quake was centred about 19 kilometres north of Yarmouth.

More recently, according to Earthquakes Canada, a 3.3 magnitude quake occurred 332 kilometres off Louisbourg on Sept. 16, and a 2.5 magnitude quake happened 17 kilometres west of Hammonds Plains on Sept. 5. Those two earthquakes were not felt by residents, the agency says.

Kolaj said there were no reports of damage from the quake on Saturday morning, and none would be expected, given the magnitude.

The seismologist encouraged residents to report their experience of the earthquake to help researchers understand how quakes of different magnitudes are felt.

Read more articles at CBC Nova Scotia 

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