Nature gives sirens at Catholic schools a ‘good live test’ Dec. 29
By Agnieszka Krawczynski
The B.C. Catholic
Loud alarms echoed in Catholic school halls seconds before a 4.7 magnitude earthquake shook the Lower Mainland Dec. 29.
The quake, with its epicentre near Sidney, B.C., caused little or no damage, but researchers at the University of British Columbia said it was a good live test of their new early warning system.
“The system worked,” said civil engineering research associate Kent Johansen.
The UBC-created early warning system detects p-waves, which are caused by earthquakes. P-waves travel faster than damage-causing s-waves, so sensing them means knowing an earthquake is coming before the ground moves.
Warning alarms rang at “all the schools that were connected to the network and which have reliable Internet,” Johansen said.
The first sensor to pick up the signal was at St. Patrick’s Elementary School in Victoria. It registered p-waves six seconds before the ground began to shake, but didn’t sound an alarm.
“Had the quake been a bit more than twice as big and potentially damaging, St. Patrick’s would have got about six seconds,” of warning. UBC alerts appeared on Twitter, but since it wasn’t a major earthquake, sirens weren’t triggered by this system. Some connected to an older system went off when shaking was detected.
“We can adjust this threshold, but we mainly aim to warn for strong events, and our threshold is already under the industry standard,” Johansen explained.
When the alarm at St. Patrick’s sounded, so did alarms at almost every Catholic school in the Lower Mainland. School was not in session; it was 11:39 p.m. during Christmas break.
Johansen said he had 13 seconds of warning from when the Victoria school picked up the p-wave to when the ground began to shake under his East Vancouver home.
He said students and teachers would have had 19 seconds of warning in Abbotsford and 36 seconds in Powell River (where it was barely felt).
Frank Dragojevich, an associate superintendent of Catholic Independent Schools of the Vancouver Archdiocese, said the system is almost complete.
“There are a few schools that aren’t hooked up for a variety of technical issues,” he said. “It’s cutting edge; nobody has really done this before, other than Japan,” and Washington state.
Johansen said UBC also got feedback that some locals would have liked to have a warning even though the impending earthquake wasn’t a major one.
“We also learned that we need to consider if we always should trigger all sirens. It would have made sense to trigger Victoria and perhaps Greater Vancouver, but not Powell River and Campbell River.”
A video of sensors detecting the Dec. 29 earthquake can be viewed at https://goo.gl/McWVys.
