Do you know what to do if an earthquake strikes?
Once again, the Great Shakeout will take place on Oct. 19 at 10:19 a.m. Hundreds of thousands of British Columbians will take part in a dress rehearsal to practise how to “drop, cover, and hold on” in the event of a high-magnitude earthquake.
The annual earthquake drill takes place worldwide and has been going on for seven years. Locally, the British Columbia Earthquake Alliance manages the event.
“It’s really about changing the culture of how B.C. residents think about the risks that we’re in and taking the steps to be personally prepared in the event of an earthquake,” said BC Earthquake Alliance president and Oak Bay Fire Department chief Dave Cockle. “It’s a message of personal preparedness… but it’s also a resource-based website that provides free info from scientists, local government, seismologists.
“It’s a public safety message. That’s what we’re ultimately trying to get across.”
Last year, more than 800,000 people in B.C. registered to participate in the Great Shakeout. Cockle said the goal this year is to surpass one million participants.
The Pacific Coast is the most earthquake-prone region of Canada due to its high prevalence of active faults, or breaks in the earth’s crust.
According to earthquaketrack.com, 31 earthquakes of at least a 2.5 magnitude occurred in or near Vancouver Island in the last year (info from Oct. 13).
The largest was a 5.7 magnitude earthquake that struck 324 kilometers away from Tofino on Jan. 7.
A 4.5 magnitude earthquake struck 170 kilometers west of Tofino on Oct. 11.
While most seismic events that occur in B.C. are too small to be felt, seismologists say the potential for a high-magnitude earthquake in or near the province is very real.
Scientists are not able to predict when earthquakes will occur, but they have analyzed historical records that map out when large ones took place in B.C. in the past.
John Cassidy, an earthquake seismologist with Natural Resources Canada, said the last high-magnitude quake to strike B.C. was on Jan. 26, 1700.
“We know from the records that it is quite variable how often they occur,” he said. “The shortest interval between those events was about 250 years and the largest interval was about 850 years. The average is about 500 years.”
Cassidy said the unpredictability of earthquakes is why it’s important to prepare for them through events like the Great Shakeout.
“We can’t predict when the next one will occur, but we know they’re hundreds of years apart and it’s been hundreds of years since the last one. So we’re certainly in the time window and the importance of being prepared for those events and knowing what to do will be what saves lives and protects infrastructure,” he said
As of Oct. 13, nearly 10,000 people in the Comox Valley are registered to participate in the Great Shakeout this year.
• Earthquakes are caused by the movement of tectonic plates relative to one another underneath the earth’s surface.
• The duration of an earthquake depends on its magnitude and the soil/ground conditions. Magnitude 6 or 7 earthquakes can result in 10–30 seconds of shaking.
• The largest earthquakes (Magnitude 8 or 9) can result in shaking for up to a few minutes.
• The biggest danger to people during an earthquake comes from falling debris.
• Earthquakes that are large enough to cause damage (Magnitude 5 and up) occur on average every few decades in B.C.
• Tectonic plates move 5–10 centimeters each year — roughly the same speed as your fingernails grow.