Getting ready for the big one

Getting ready for the big one

Studying earthquakes of the past helps British Columbians prepare for future natural disasters
January 9, 2013

While the magnitude 7.5 earthquake that hit off the coast of Alaska on January 4, 2013 generated only small tsunami waves, it served as a reminder to researcher John Clague that the same kind of natural disaster could strike again. And the next time, it could be bigger.

Clague, Canada Research Chair in Natural Hazards Research and a geologist at Simon Fraser University in Vancouver, says big earthquakes that cause huge tsunamis, such as the Japan quake, have recurred every 500-600 years over the last 10,000 years. The last big one to devastate B.C. was in AD 1700, which means that the province could be due for another disastrous quake.

“We have a pretty high likelihood that we’re going to experience such an event over the next 200 years,” he says. “We can’t prevent earthquakes and tsunamis, so all we can do is come up with strategies for getting people out of the way.”

A key part of finding those strategies, he says, is knowing the extent of the natural disasters that have come before. Clague’s research is like detective work. He searches out evidence of past earthquakes and tsunamis that remain “archived” within the Earth. Traces of past tsunamis are preserved as waves of ocean sediment dragged inland to such places as low-elevation, freshwater lakes along the B.C. coast. By digging down into the sediments, Clague and his students have found layers of ocean sand containing marine fossils — a smoking gun that indicates that a towering ocean wave once reached into the lake. They then piece together the timing of the event by carbon dating the fossils.

“If you piece together enough records of that type from all around the coast,” says Clague, “you start to get a sense of a footprint of the tsunami on the landscape.” 

Equipped with this kind of information, Clague attempts to bridge the gap between scientists and civil society. “There has always been this chasm between the knowledge physical scientists have, and how to incorporate that into the decision-making process,” he says. 

To that end, SFU’s Centre for Natural Hazard Research sponsors workshops each year for municipal, regional and provincial decision makers in an attempt to “engage them on planning,” he adds.

Clague, who came to Canada in the late 1960s from his native California, began focusing on historical earthquakes while at the Geologic Survey of Canada. At the time, scientists were just realizing that the likelihood of big earthquakes on B.C.’s south coast was higher than previously thought.  

In the future, Clague hopes to focus more attention on predicting the threat from smaller, but still potentially deadly earthquakes close to the B.C. coast, similar to the type that struck Christchurch, New Zealand, last year. He says there are still many small geologic fault lines in the Pacific Northwest that remain uninvestigated.

“The next challenge,” he says, “will be to look critically at the existing faults to determine if they’re storing geologic strain that will be released in a future earthquake.”