Thousands of British Columbians took cover Wednesday morning as part of the largest simultaneous earthquake preparedness drill ever executed in Canada.

An estimated 460,000 people in churches, schools and offices across the province hid under the nearest sturdy surface at 10 a.m. local time, in an event dubbed the Great British Columbia ShakeOut. Provincial legislators, however, opted out of the drill, cancelling their planned participation moments before it began.

It was B.C.'s first time trying out a simultaneous test run, in which radio stations sounded a synchronized alarm urging participants to take cover. They were instructed to get under a table, hold on tight and stay there for one minute -- about two to five minutes short of the expected duration of a real quake.

Organizers also advised participants on what not to do: run.

"If you're downtown, do not run outside the building," said Discovery Channel's Mark Miller, whose investigation of infrastructure failure during Chile's massive 2010 earthquake airs today on "Daily Planet."

"(In Chile), some of the buildings lost their glass," he told CTV News Channel today. "You're going to survive the quake but you're going to die from a big chunk of glass hitting you in the head."

While B.C. hasn't had a major earthquake since a 9.0-magnitude tremor in 1700, the province sits in a geological region that puts it at risk. Seismologists warn another major quake they're calling "The Big One" could happen anytime.

Miller, who visited Chile last March, says drills like today's remind ordinary citizens of that possibility.

"It gets people thinking about where (they would) hide out, where (they would) put their kids," he said.

With its proximity to the ocean, B.C. could also be prone to a post-earthquake tsunami, so those near the water should plan an exit to higher ground.

"You might have 45 minutes, you might have less," he said.

But despite its citizens' readiness, B.C.'s building codes could leave it vulnerable to significant earthquake destruction, according to Miller's investigation.

"A lot of the buildings that failed (in Chile) were newer," he said. "These buildings are starting to use a new trend in building design: thinner walls… to allow people to use space better. Those walls aren't quite as earthquake resistant."

He said British Columbia building codes aren't up for review until 2014, and in the meantime, it remains "perfectly legal to build with what may be flawed building techniques."

Miller's investigative piece airs on Discovery Channel's Daily Planet at 7 and 11 p.m. ET.