Blance Rock, near Skidegate on the Haida Gwaii.John Lehmann/The Globe and Mail
Earthquake experts are expected to head to Haida Gwaii as soon as today to install several strong motion sensors as part of an effort to better understand the 7.7 magnitude quake that shook the islands last Saturday.
The new equipment will become the latest installations in a provincewide monitoring system that began in 2005 and now features sensors in about 130 locations, including dams, roads and bridges. And while the shoebox-sized instruments can't predict earthquakes, they could play a role in developing early-warning systems, said John Cassidy, a seismologist with Natural Resources Canada.
"They are useful in telling us how the ground shaking varies with distance from an earthquake," Dr. Cassidy said on Wednesday. "We can learn from these instruments about how seismic waves travel through the earth.… you can learn from the remote areas and apply that to more populated regions."
An earthquake that occurred 100 kilometres from Vancouver, for example, might take 30 seconds to result in shaking in the city, he explains. Sensors at or near the quake site could provide a warning for the city. If an earthquake were farther away and started in, say, California, a strong motion sensor could provide four or five minutes of warning.
That may not seem like much, but even such a small window could make a difference for people or infrastructure.
In a test run of the technology in Japan last year, motion sensors tied in to the country's automated transportation system stopped bullet trains from entering tunnels or going on to bridges when a 9 magnitute quake hit the country, Dr. Cassidy said.
NRCAN and other agencies have developed the technology over the past decade or so. Commercial versions are now available for between $2,000 and $3,000, compared with the $15,000 for previous technology.
The sensors provide near-real-time information and, in urban settings, are designed to help assess whether structures such as bridges and roads have been damaged by a quake.
The BC Smart Infrastructure Monitoring System, or BCSIMs, is a joint effort between NRCAN, B.C.'s Ministry of Transport and the University of British Columbia's civil engineering department.
The system is designed to help provincial officials perform "triage" by rapidly assessing bridges and roads most likely to have been affected by seismic activity, a spokeswoman for the ministry said in an e-mail.
The pending installations will be the most remote to date for the technology, which requires a power source and Internet access.
The new Port Mann and Pitt River bridges have sensors, as does the Ironworkers Memorial Bridge.
Last Saturday's earthquake off the coast of B.C. was Canada's largest in more than 60 years and triggered tsunami warnings, later lifted, for parts of coastal B.C. No serious injuries or damage was reported.
Wendy Stueck