Researchers gathering new earthquake data off Vancouver Island

A deep-sea mission off the coast of northern Vancouver Island is gathering new data on one of the most seismically active regions in North America. The crew has returned from the 17-day mission launching the project, which will contribute to future planning for earthquakes and tsunamis.

“It’s a five-year program that’s looking to study the earthquake hazards in the Canadian pacific, predominantly offshore region,” says the chief scientist aboard the cruise, Andrew Schaeffer. “One of the highlights of this cruise actually is that this is now the biggest deployment of Canadian broadband ocean bottom seismometers in Canadian waters.”

The program is led by the University of British Columbia and involves the Geological Survey of Canada, the University of Victoria and Dalhousie University.

The team has sunk 28 instruments, called ocean bottom seismometers, to the ocean floor to record seismic activity in the Revere-Dellwood Fault – an area between Haida Gwaii and northern Vancouver Island.

“This is an area that has also never had any ocean bottom seismic equipment deployed in it, so it’s a fascinating place to study,” says Schaeffer. “By having instruments in this region where the earthquakes occur, we can get a complete catalog of the small seismicity and that allows us to better understand and model how many big earthquakes we would get.”

The researchers say the information will provide input to the Canadian Seismic Hazard Model, which helps guide national building codes.

“It will give us the best images of structure in that area and of earthquakes in that area,” says Geological Survey of Canada earthquake seismologist John Cassidy. “So understanding how often that level of ground shaking, that’s the information that engineers need when they’re designing structures, bridges, buildings, hospitals.”

Dalhousie University’s National Facility for Seismological Investigation is managing the instruments being used. There’s a national pool with 120 of them, which are being resourced for different universities and government departments for investigations.

“They can stay down for up to about 18 months recording autonomously and then we come back and tell them to release with an acoustic signal and they will float to the surface on their own where we pick them up, offload the data and recharge them,” says NFSI manager Graeme Cairns.

“Part of the idea of using these offshore instruments is to compliment the network on land so you have more complete coverage.”

The team plans to leave the ocean bottom seismometers in the area for the year, and then they’ll redeploy them somewhere else.