|A graphic displays ETS tremor events over the last month.|
You might not have noticed it, but over the last few months Victoria moved a little farther away from Vancouver.
The south portion of Vancouver Island has shifted about five millimetres — about the width of a pencil — westward, thanks to recent seismic activity.
A series of small tremors over the last few weeks have pushed Vancouver Island away from the B.C. mainland, according to a federal scientist.
For the first time in several weeks, #VancouverIsland is ETS tremor-free.— John Cassidy (@earthquakeguy) July 13, 2018
From June 18 - July 11 there were about 10,000 tiny ETS tremors, and the southern part of the island shifted (about the width of a pencil) to the west.#ActiveTectonics
What is ETS? https://t.co/urSgiNhwTU pic.twitter.com/1rUQY0aw3K
"Over the past few weeks the southern half of Vancouver Island has actually moved about four or five millimetres to the west towards Japan. It's something that happens around the world in similar tectonic settings," Cassidy told CBC.
The movement happens when the Juan de Fuca tectonic plate, which sits off the coast, sinks beneath the North American plate, where the island is located.
The two plates meet along the Cascadia Subduction Zone, a 1,000-kilometre-long fault that runs from northern Vancouver Island to northern California.
The Juan de Fuca plate is being forced underneath the North American plate, but a section of that boundary has become locked together, which means the plates are no longer sliding smoothly.
All the energy from that movement is being stored up inside the rocks, waiting for the moment it will be released as a catastrophic megathrust earthquake — otherwise known as "The Big One."
During the past 24 hours the tiny ETS tremors (not felt) have left the greater #Victoria region and returned to the #CowichanValley, #Duncan, and #Ladysmith. The number of events has been dropping off very quickly - only a few each hour this morning.— John Cassidy (@earthquakeguy) July 11, 2018
ETS: https://t.co/urSgiNhwTU pic.twitter.com/nWam2U3pcz
The above post is reprinted from CBC/Radio-Canada.