A federal government seismologist said Monday that a weekend earthquake off Vancouver Island is a “reminder” that a much bigger event is going to hit B.C. at some point.
John Cassidy, a seismologist based in Victoria with Natural Resources Canada, said the 5.5 quake occurred west of Nootka Island off the west coast of Vancouver Island at 6:22 a.m.
The nearest community to the quake was Gold River.
A similar ‘moderate’ quake of 4.9 magnitude occurred July 26 in approximately the same area of a subduction zone that extends from northern Vancouver Island to Northern California.
“[Sunday’s] earthquake wasn’t an unusual event,” said Cassidy. “But it’s really a reminder we live in a very seismically active region.
“We know that much larger earthquakes have occurred in the past and we know that they will happen again in the future,” he said.
But the science has not advanced to the point where such an event can be predicted.
Cassidy said the tectonic plates grinding away at each other in the subduction zone are moving at a rate between two and five centimetres per year, about the same rate as fingernails grow.
But over the course of 100 years, that movement translates into two to five metres.
“That’s a lot of motion,” said Cassidy.
The rocks along the fault line don’t always move, although the plates below them are moving.
Energy from that movement is stored until the strength of the rocks is exceeded.
“It’s almost like breaking a stick,” said Cassidy.
That is when the more massive earthquake in the magnitude of seven to nine occurs.
