UVic geologist discovers active fault line running under Greater Victoria
A Landsat image of southern Vancouver Island shows the surface trace of the Leech River fault and its intersection with the population centers surrounding Victoria, B.C. March 31, 2017. (GSA Today)
CTV Vancouver Island
Published Friday, March 31, 2017 11:19AM PDT
A University of Victoria-led team has discovered that a fault line running under Greater Victoria previously thought to be inactive is not only active – it’s caused earthquakes in the region before.
The Leech River fault runs a few kilometres from downtown Victoria, including the Esquimalt Lagoon area, and just offshore from James Bay and Clover Point, according to geologist Kristin Morell’s study.
She’s determined the fault has caused at least two major earthquakes since the last glaciation period more than 15,000 years ago, meaning it’s active and a potential hazard for the region.
But the fault carries no risk of causing a megathrust earthquake, also referred to as the “Big One,” the study says.
Crustal faults like the Leech River fault can fall silent, displaying no seismic activity for thousands of years and making them difficult to study.
Instead, Morell had to study topographic features of the region to see how past earthquakes shaped the area.
“Now that we’ve identified that the Leech River fault is active, the next step is for us to nail down exactly when and how big the most recent earthquakes were,” she said.
Morell’s findings have since been used in seismic vulnerability assessments done by the City of Victoria, and they can also be used to help with hazard mitigation and emergency response planning.
“When we understand the risks posed, there’s a lot we can do to keep out communities safe,” she said.
Morell’s study was published earlier this month in the Geological Society of America’s publication GSA Today and includes contributions from Lucinda Leonard and Vic Levson from UVic’s School of Earth and Ocean Sciences, as well as researchers from Boston University and Western Washington University.