News and Features
The Big One
By Remy Scalza published Apr 10, 2012
Vancouver is due for a big earthquake. The question is, are we ready?
For someone whose business is disaster, Anne Ward is uncommonly charming. Today, Ward, an older woman who lives in Kitsilano but is originally from Saskatoon, is wearing two-inch silver heels, a shimmering gold shawl, and jade earrings with a matching amulet that looks vaguely Mayan. “I figure you got to look good while you can,” she says with a slight prairie twang. “It’ll come soon enough.”
Ward is president and CEO of Krasicki and Ward, an emergency preparedness supply store in City Square Mall at 12th and Cambie, right next to a beauty salon and below a Fitness World. The “it” she’s referring to is the big one, a major earthquake. In her store, you can buy earthquake survival kits, big bricks of high-calorie rations, crowbars and hatchets, solar-charged flashlights, emergency toilets in a bag called Wag Bags, and most anything else needed for the apocalypse. “You can try calling 911, if the phone lines are operational,” she says, raising a knowing eyebrow. “But you know what? You might not be their highest priority.”
Ward escorts me past shelves of first-aid kits, hand-cranked radios, and something called QuakeHOLD! Gel™ for Glass and Crystal to a rack stocked with her bestsellers: pre-packed gym bags stuffed with essentials for the first 72 hours ($43.99 for the one-person standard kit). There’s drinking water in aluminum foil packets, rations that taste like shortbread, a Mylar blanket, pressure dressings. Ward suggests I pick up a kit now, while they’re still in stock. “After the Japan quake, we completely sold out of emergency food and water. The phone rang off the hook for days. We had nothing left.”
Taped to the store window is a printout of all the earthquakes recorded in British Columbia in the last week. Dozens of tremors shook the province, including a 4.0 magnitude quake in Port Hardy. That’s not an unusual week. British Columbia is located along the edge of the Pacific Ring of Fire, one of the planet’s most active tectonic zones. Nine of the 10 largest earthquakes on record have happened along its flanks, including the 2011 Japan quake, the 2010 Chile quake, and the 2004 Indian Ocean quake, which together killed roughly 250,000 people. There are no B.C. earthquakes on this top 10 list. Yet.
The question isn’t if an earthquake like the one that devastated Japan last March will hit Vancouver. It’s when. The Japanese quake, which killed more than 20,000 people and caused up to $300 billion in economic damage, as well as the Chilean and Indian Ocean earthquakes, are examples of what seismologist call megathrust events. Occurring at the boundaries of tectonic plates, these are the planet’s largest earthquakes, capable of achieving magnitudes of 9.0 and above. (For perspective, the shaking in a magnitude 9.0 earthquake is about 500 times stronger than the shaking in the 2011 magnitude 6.3 earthquake that struck near Christchurch, New Zealand, killing 184 people. The familiar Richter scale isn’t even capable of measuring the true size of a megathrust earthquake—it maxes out around a relatively modest 7.5. Scientists instead rely on something called a moment magnitude scale to assess the strength of these temblors.)
Geological records show that megathrust quakes have violently shaken southwestern B.C. at least 13 times in the last 6,000 years. The last one was a 9.0 quake off the west coast of Vancouver Island on the evening of January 26, 1700, 78 years before Capt. James Cook became the first European to set foot here. According to First Nations oral traditions, the ground shook so hard that people couldn’t stand, for so long that it made them sick. The ensuing tsunami destroyed whole villages and washed canoes into trees. Monster waves crossed the Pacific and rocked the coast of Japan, showing up in historical records that allowed researchers to pinpoint the exact time and date of the quake.
On average, we can expect one of these megaquakes every 500 to 600 years in B.C., though they have occurred as little as 210 years apart. Our clock has been ticking now for 312 years. “The best estimate we have is a 10 to 15 percent chance of a megathrust event within the next 50 years,” says John Cassidy, head of earthquake seismology at the Geological Survey of Canada, Pacific Division. “But there are huge uncertainties. It could happen later this afternoon.” Cassidy, who’s stationed near Sidney on Vancouver Island, comes off more as amiable high school science teacher than perhaps Canada’s preeminent earthquake authority. Between explaining plate dynamics, he tells me of the morning back in 1990 when he was typing up his doctoral thesis on earthquakes at UBC and a 5.0 quake hit Washington, shaking him at his computer. “It was a sign,” he says, “that I was in the right field.”
The cause of B.C.’s seismic troubles lies in the Cascadia Subduction Zone, a 1,300-kilometre undersea fault that runs along the west coast from Brooks Peninsula on Vancouver Island to Cape Mendocino in Northern California. Here, the undersea Juan de Fuca plate is sinking, or subducting, beneath the North American plate at the rate of about 4.5 centimetres a year. Or at least it’s trying to. For the last three centuries, the plates have been locked up, grinding together but getting nowhere. After all that time, the North American plate is now springloaded to lurch up to 14 metres west in the next megathrust quake. “We’re talking about three or four or even five minutes of intense shaking,” Cassidy says. “And it’s not just one city. It’s Vancouver, Victoria, Seattle, Portland. Even high-rises in Toronto could sway.”
Seismically speaking, this isn’t our only concern. Between these monster events, mounting stress within plates triggers other kinds of earthquakes both in the earth’s crust and deep below. Hundreds of these temblors, known respectively as crustal and deep earthquakes, happen every year in B.C., as Anne Ward’s sign attests. Most are never felt. Some are. On June 23, 1946, a 7.3 crustal earthquake struck central Vancouver Island, the strongest quake recorded on land in Canada. It caused only two deaths, but were a similar quake to strike beneath Vancouver, the results could be disastrous. Cassidy draws a comparison to the 6.9 Kobe, Japan, quake in 1995 that killed more than 5,500 people and damaged some 200,000 buildings. “Because these earthquakes are close to the surface, the shaking tends to be much stronger and more damaging.” Cassidy estimates that there’s a 10 percent chance of one of these powerful crustal or deep earthquakes striking here in the next half-century.
In other words, Vancouver isn’t facing the prospect of the big one, but the big ones. Adding up our multiple seismic threats—crustal, deep, and megathrust—there’s a one-in-four chance of a major, destructive earthquake striking in the next 50 years. This isn’t a worst-case scenario. It’s the consensus among the country’s leading seismologists. And nothing keeps them up at night quite like the big daddy, the full-on 9.0 megathrust.
