A day after a 4.7-magnitude earthquake shook southern B.C., the City of Vancouver says its structural engineering consultants are inspecting local bridges to check for damage.
Dr. Tony Yang, a professor of civil engineering at UBC, says crews are likely to first look for visual structural damage, such as cracks in walls, foundations, and columns.
But there is also non-structural damage to look out for, he says.
“Functionality of all the non-structural equipment could also be impacted, but probably not in the earthquake yesterday,” Yang said
“But in a major earthquake, we expect non-structural components will also be damaged.”
He says a large quake, with a magnitude of 6 or 7, could cause significant damage, but he says most of Metro Vancouver’s structures that were built in the last 50 years are able to withstand them.
“You have about a 98 per cent chance that your structures will be able to withstand the load,” he said
While this means the buildings won’t collapse, that doesn’t mean there will be no damage.
“If you wanted to have higher performance, where you want to be damage-free, the technology is already available but most owners don’t know,” Yang said.
Collapse prevention is the minimum standard, but there could still be significant, expensive damage.
“If some places are looking for higher performance, then the owners can request to have better performance for like no damage or low damage,” he said.
Ring of Fire
Yang says Vancouver is situated on what is called the “Pacific Ring of Fire.”
“This is where we have the most seismically active regions in the world, starting from where we are, if we keep going south we have California, we have Mexico, we have Chile,” he said.
“And then we go around the earth. We have New Zealand, Indonesia, Taiwan, Japan, Alaska, and then back to Vancouver.”
Many large earthquakes have happened in the Ring of Fire over the last couple decades, he says.
“For example, the 2011 Tohoku earthquake, it’s a very major earthquake that hit Japan, and we had one major earthquake hit New Zealand the same year and the year before in Chile.”
A large earthquake like those he mentioned could very well hit the Pacific Northwest, he says, and the expectation is that structures would be severely damaged.
But Yang says two pieces of good news came out of Friday’s quake.
“One, it wasn’t too big, so we don’t have too much damage to the structures,” he said.
“But also, [it allowed] earthquake energy to be released. If you don’t, over time, if we start building up, then it will add up to this large earthquake happening.”
The quake, which struck 20 kilometres northwest of Sechelt just before 1:30 p.m. Friday, was felt by thousands across Metro Vancouver and the Sunshine Coast and as far away as Lillooet.
No injuries have been reported.
1130 NewsRadio has reached out to the Mayor’s office for the latest information on any possible damage.