After dozing off on the couch with an issue of New Scientist magazine, Fred Anderka awoke to a loud rumbling that sounded like a freight train passing by his two-storey log house on Sidney Island, one of British Columbia's Southern Gulf Islands speckled with vacation properties that mostly lie vacant during the winter months.
The wildlife biologist had experienced the prolonged vibrations of small earthquakes while living in the Ottawa Valley, but he says the noise from Tuesday night's 4.7-magnitude earthquake – located close to the island and about 50 kilometres underneath the Earth's crust – was much more intense.
"[It] wasn't of things rattling in the house, I think the noise was actually from the acoustic waves coming from the quake itself," said Mr. Anderka, who has lived there with his wife for the past three years.
Across the island, which lies about 20 kilometres northeast of Victoria, Raymond Rae and his wife were startled awake at 11:39 p.m. by the glass rattling on their balcony for several seconds, and then by their 10-year-old Labrador retriever Daisy sprinting up the stairs into the bedroom.
"Rock and roll would describe it pretty well," said Mr. Rae, who added Wednesday that his dog has since stuck to them "like glue."
The moderate earthquake was felt roughly 150 kilometres in all directions across much of B.C.'s South Coast and parts of Washington State.
No damage or injuries were reported, and it did not spawn a tsunami, but experts say the largest earthquake to hit the area in more than a decade should prompt greater preparation for the megathrust earthquake of a magnitude 9 or greater that will eventually occur.
"I don't know if you got woken up or not, but literally this can be considered a wake-up call for every one of us who live in this region that we are in an active seismic zone," said Honn Kao, an earthquake seismologist with the Geological Survey of Canada.
"Because the scientific technology we have today will not be able to have very precise predictions of earthquake occurrences, the message is we should definitely be well prepared for the seismic hazards that can happen at any time."
He said Tuesday's deep earthquake was "essentially the same" type as the magnitude-6.8 earthquake that hit in 2001 underneath Nisqually, Wash., and shook nearby Seattle and even Metro Vancouver. These deep earthquakes rarely get stronger than that, but Dr. Kao said the region is soon due for another much larger megathrust earthquake – similar to the deadly 2004 Indian Ocean earthquake that created a massive tsunami in Indonesia and the 2011 Japanese earthquake that ruined the Fukushima Daiichi nuclear power plant.
The Cascadia coastal subduction zone – which stretches from the northern tip of Vancouver Island to northern California – has averaged one of these massive earthquakes roughly every 500 years, he said.
"They have occurred as short as 20 to 50 years in between and as long as 800 years," Dr. Kao said.
Since the last megathrust occurred in 1700, "we've already entered the possible time window" for another similar earthquake, he said.
B.C. Minister of State for Emergency Preparedness Naomi Yamamoto urged residents to make plans for communicating and meeting up if separated during a big quake. A list of items for an emergency kit – including water, flashlights and a battery-powered or hand-crank radio – can be found on the B.C. government's website.
The province said in a statement that it had either committed or already invested billions of dollars in seismic upgrades since 2001, including $2.2-billion for high-risk schools and $9.1-billion for hospitals.
John Clague, professor of earth sciences at Simon Fraser University, said though the government has been criticized for the pace of these upgrades, its program has "received a lot of recognition internationally as a good way to address a serious issue."
"We should be keeping the pressure on government not to short-circuit that whole process, but I think it has been done appropriately," he said.
Of equal concern, he said, was the ability of Metro Vancouver's bridges to withstand a megathrust earthquake, which could grind transportation in the region to a halt if they are destroyed. The province said Wednesday that it has spent $4-billion on new bridges and large highway infrastructure projects built to modern seismic standards, including the Port Mann Bridge in Metro Vancouver.
The City of Vancouver confirmed Wednesday no known reports of damage, and BC Hydro reported the quake had no impact on its electrical transmission and distribution systems. Two of Metro Vancouver's elevated rapid-transit lines were shut down briefly while the guideways were checked, but TransLink said the system was back in operation within 90 minutes.
More than 2,500 people filled out online forms to help Canadian authorities track the seismic activity, while another 13,000 reported the earthquake to the U.S. government. Still, thousands more immediately took to social media to post that their beds were shaking or windows were rattling.
B.C.'s biggest quakes
A seismograph placed in Victoria in 1898 was the first in B.C. to begin scientifically recording seismic activity. The following is a list of the biggest known earthquakes in the province in recent history.
- Jan. 26, 1700: Off the west coast of Vancouver Island. Though no scientific instruments were in place to measure the last time a megathrust earthquake hit the region, the resulting tsunami was so large it travelled across the Pacific Ocean, damaged Japanese fishing villages and was recorded by imperial bureaucrats at the time. The tsunami also decimated the indigenous people living in Pachena Bay on Vancouver Island’s southwest coast. Presumed magnitude: 9.0
- June 23, 1946: Centre of Vancouver Island. B.C.’s largest onshore earthquake caused extensive damage to island communities and two deaths. Chimneys reportedly crumbled and landslides were triggered across the middle of the island. Magnitude: 7.3
- Aug. 22, 1949: Offshore of Haida Gwaii. This earthquake was the strongest ever recorded in Canadian history. It reportedly tipped over cows and knocked people off their feet, but didn’t cause any deaths. Magnitude: 8.1
- June 24, 1970: South of Haida Gwaii. This earthquake caused no known casualties but created landslides on the islands. Magnitude: 7.4
- Oct. 27, 2012: Moresby Island of the Haida Gwaii. The second-largest Canadian earthquake ever recorded by a seismograph struck just after 8 p.m. but caused no major injuries or structural damage. Residents of the islands were evacuated to higher ground and a tsunami alert warning was issued, but no major waves were recorded. The hot springs at Gwaii Haanas National Park Reserve almost dried up completely after the earthquake, but they have since shown signs of a slow recovery. Magnitude: 7.8
With a report from The Canadian Press