An undersea network of seismic sensors is slowly starting to take shape off the B.C. coast to provide early warning for Lower Mainland residents and authorities just before an earthquake strikes.
The first sensor was deployed at a depth of 850 metres in Barkley Canyon off Tofino in June by Oceans Network Canada, a non-profit company founded by the University of Victoria that got $5 million from the B.C. government to develop the network.
It’s a three-year project that aims to have a series of sea- and land-based sensors in place by March of 2019, followed by software systems to analyze and determine what type of customized warning the end user should get, depending on their location.
“Hopefully in three to five years or so we’ll be able to give you a warning to tell you to get under the table or take some safety measures before the shaking starts, which to us is the holy grail of public safety to be able to protect people from injuries and potentially save lives,” said Teron Moore, a business analyst at Ocean Networks Canada.
Advance warning is possible because the initial energy wave from an earthquake that doesn’t cause damage travels faster and can be detected well ahead of the wave of ground-shaking energy.
How much warning is possible depends on how far away a quake’s epicentre is and how close the nearest sensor is positioned to detect it and transmit the alert.
Ocean Networks Canada anticipates 60 to 90 seconds of warning can be given to populated areas of southwestern B.C. ahead of a major earthquake centred well off the coast.
It’s hoped that in future, much of the population will get enough warning from the emerging systems to take cover or even escape risky locations. Automated alerts could go out on radio and TV and through smartphone apps, Moore said.
Gas lines could be shut off and critical infrastructure could be protected. Traffic could be kept from tunnels and bridges. Elevators could automatically descend. And trains full of people or hazardous cargo could slow to a halt rather than derail at high speed.
While Ocean Networks Canada has tackled the seafloor sensors first, a group of UBC researchers has been deploying land-based sensors because they can be installed at a fraction of the cost.
They already have a working system up and running using a network of 30 ground-motion sensors that almost instantly triggers an alarm at 71 receiving sites – mainly private schools because the Catholic diocese stepped up early to support the project.
Data is available publicly on their website and alerts are also sent via a Twitter account (@EEW_BC) and an Android phone app.
UBC research engineer Kent Johansen says the Ocean Networks seafloor sensors will give more warning of an offshore quake than the nearest land-based sensors at Jordan River or Campbell River, or even additional sites being deployed at Tofino and Ahousaht.
But he said the land-based network is critical to warn of the shallower crustal earthquakes that can strike between Vancouver and Victoria and be severely damaging because of their proximity.
He pointed to a 1946 quake near Courtenay and another in 1976 off Salt Spring Island that both caused damage in Vancouver.
“They happen more often,” Johansen said, likening that scenario to the 6.3 magnitude earthquake in 2011 that severely damaged Christchurch, New Zealand.
“If we get hit by a just a six-pointer somewhere in the Strait of Georgia, it’s fatally damaging for Vancouver.”
UBC research engineer Kent Johansen. Brent Hayden photo
He said land systems could also be nearly as effective as seafloor ones in detecting a massive off-shore mega-quake.
Cascadia subduction zone quakes tend to start at one end of the fault off Oregon or Haida Gwaii and rip all the way to the other end, he said.
So the UBC team is contemplating extra distant sensor sites in Oregon and on B.C.’s north or central coast that might detect the start of such a quake earlier.
B.C. residents dropped under tables and desks Thursday morning during the Great B.C. Shake Out to drill on what to do in the event of an earthquake.
— ShakeOut BC (@ShakeOutBC) October 20, 2016
But to Johansen, such drills underscore the need for more advanced early warning systems to advise residents, beyond simply having public address systems broadcast a pre-recorded message to take cover and wait.
He imagines bored kids under school desks that get up and start wandering around a minute or two after an early warning alert arrives. “I just feel if it goes on for three minutes, school kids don’t have that kind of patience.”
Johansen aims to improve the system to provide real-time updates on whether the initial alert was a false alarm or the quake is still coming.
“It might say ‘Earthquake in progress off Tofino. Estimated time to shake 15 seconds. Please remain covered.’”
People who know it’s going to be minutes instead of seconds could decide to move somewhere safer, he said, adding he envisions a change someday to the current policy of just staying covered in place as warning systems evolve.
A crab watches as a Titan accelerometer is lowered into a special chamber in the sea floor in Barkley Canyon off Tofino to form the first node in a network of earthquake early warning sensors. Ocean Networks Canada photo.