Sooke really knows how to shake, rattle and roll – literally.
There have been more than 60 earthquakes within 50 kilometres of Sooke recorded in the last year, according to the Natural Resources Canada.
The latest occurred Sept. 5 just 26 kilometres south of Sooke with a magnitude of 1.7. It was the second earthquake in less than 24 hours.
“Typically in a year around Vancouver Island we’re looking at nearly 1,000 earthquakes a year, so it’s a very active region, but most of those are off shore,” said Dr. John Cassidy, a seismologist at NRC.
Sooke is located in the Cascadia subduction zone, and the Juan de Fuca plate is moving towards Sooke about 40 kilometres deep.
The fault is storing energy, and as the plate inches towards us, the fault buckles and releases some tension, resulting in the little shakes we feel on the Island, Cassidy said.
Cassidy said the ocean plate is creeping towards the continent at a rate of about four to five centimetresa year; roughly the same speed your finger nails grow. Eventually the plate will reach us and start to bend, and turn, it will create an earthquake of a much larger scale. However, that may not happen for hundreds of years.
Cassidy said to compare this collision to a stick bending; there is only so much pressure you can put on it before it breaks. The same is true for tectonic plates. They too will store energy for a time, but eventually they will break and slip.
There is no way to predict when the plate will collide with North America, but Cassidy said the NRC looks at where earthquakes are most likely to occur and gets an idea of how large they can be from studying past earthquakes around our region as well as regions around the world similar to ours, such as Japan, Alaska and Mexico.
“We study old earthquakes, new ones, and other ones around the world, and we use this information to work with engineers and emergency managers who are looking for realistic scenarios on what we can expect in the future in terms of earthquakes and tsunamis, and how we can prepare for that,” said Cassidy.
“The more people know about earthquakes, the better prepared we can all be.”