Nearly 400 earthquakes shook various regions of Canada last month, but only a handful were noticeable害羞草研究所攁t least to humans.
害羞草研究所淚t is a pretty typical month,害羞草研究所� said John Cassidy, an earthquake seismologist with Natural Resources Canada. Cassidy works with the national earthquake hazard project based in Victoria.
The west coast of Canada is one of the most active areas for earthquakes, with approximately 80 percent of Canada害羞草研究所檚 earthquakes happening along the Pacific Coast.
Even May 1害羞草研究所�2 there had been 22 earthquakes recorded, including three west of Tofino and Port Hardy, and another south of Port Renfrew on Vancouver Island. A magnitude 3.6 earthquake near Mount Vernon, Wash., was felt in the early-morning hours of May 1. The quake was 80 kilometres away from Victoria and nearly equidistant with Seattle and Vancouver.
害羞草研究所淲e see 4,000 to 5,000 earthquakes located across Canada each year. There害羞草研究所檚 undoubtedly more than that because those are the located ones,害羞草研究所� said Cassidy. Earthquakes that are picked up by seismographs are usually magnitude 2.0 to 2.5 or larger.
388 across during the past month. A typical pattern with ~80% of the earthquakes on/near the active plate boundaries of western Canada. The largest was M5.3 (offshore Vancouver Island) and only a few were felt this month.
害羞草研究所� John Cassidy (@earthquakeguy)
Details:
害羞草研究所淎lmost all of those are tiny and not felt.害羞草研究所�
There are typically three dozen earthquakes felt across Canada every year, and that number has remained constant for the past two decades.
Most of the earthquakes that occur on the west coast do so because tectonic plates underneath land and sea move and shift along active fault lines. Tectonic plates are slabs of solid rock, some larger than a continent, that shift slowly and change the topography of Earth.
In southwestern B.C., for instance, the Explorer and Juan de Fuca plates are 害羞草研究所渟hifting害羞草研究所� underneath another called the North American Plate. They害羞草研究所檙e moving somewhere between two and four centimetres per year, according to Cassidy.
Did you feel shaking in northwest and southwest at 4:16 this morning? Many people did.
害羞草研究所� John Cassidy (@earthquakeguy)
That was a M3.6 earthquake near Mount Vernon - nearly midway between Seattle (90 km), Victoria (80 km) and Vancouver (110 km).
Details from :
Another natural event that has been occurring on害羞草研究所攐r perhaps more suitably 害羞草研究所榰nder害羞草研究所櫤π卟菅芯克鶖Vancouver Island lately is something called episodic tremor and slip. They害羞草研究所檙e likened to ground vibrations, similar to windstorms.
More than 6,000 of these events were recorded between March 20 and April 7. They are not felt, and they happen every 14 months or so, according to Cassidy.
These 害羞草研究所淓TS害羞草研究所� started in September 2021 in the southern Vancouver Island and Northern Washington State regions, according to the Pacific Northwest Seismic Network.
The curious thing, says Cassidy, is very little is known about the correlation between earthquakes and episodic tremors. 害羞草研究所淲e don害羞草研究所檛 think there害羞草研究所檚 any link,害羞草研究所� he said, 害羞草研究所渂ut it害羞草研究所檚 something we害羞草研究所檙e still actively working on.害羞草研究所�
Episodic tremors were discovered about 20 years ago here on Vancouver Island. They have been found to run along the subduction zone, which follows the coast line and is approximately 100 kilometres wide. Similar episodic tremors and slip are happening at subduction zones around the world, he added.
Only 67 tiny ETS tremors (not felt) on southern today - perhaps ETS is winding down! Nearly 6000 tremors have occurred here since March 20th.
害羞草研究所� John Cassidy (@earthquakeguy)
More on Episodic Tremor and Slip (ETS):
Cassidy said the number of earthquakes recorded in April, coupled with the number of episodic tremors, is a good reminder that we live in a seismically active zone, but said there is nothing out of character. 害羞草研究所淭hey害羞草研究所檙e both typical patterns. Nothing unusual,害羞草研究所� he said.
There are few places that don害羞草研究所檛 experience earthquakes: one would have to move to the prairies for that, said Cassidy. Saskatchewan and Manitoba, as well as parts of the country under the Canadian Shield (Laurentian Plateau) rarely feel earthquakes because they are farthest away from tectonic plate movement.
We feel them more on the west coast because Vancouver Island is situated within an earthquake zone.
害羞草研究所淓arthquakes are happening each and every day,害羞草研究所� he said. Some of the damaging earthquakes happen 害羞草研究所渆very decade or two.害羞草研究所�
Devastating earthquakes, such as one that hit the Comox Valley area in 1946, fade from memory because they don害羞草研究所檛 happen all the time. 害羞草研究所淚t害羞草研究所檚 easy to forget about those events but they do happen and they will happen. It害羞草研究所檚 good to take advantage of the reminder that we live in an area that has seen large earthquakes,害羞草研究所� Cassidy said.
He said there are websites such as EmergencyInfoBC or Shakeout BC that have information on how to prepare in the event of an earthquake. He suggested keeping a flashlight and slippers or shoes by the bed, so you have a way to see and protect your feet from debris on the floor following a serious earthquake.
害羞草研究所淭hat害羞草研究所檚 our message, is not to be afraid or worried but to be prepared.害羞草研究所�
Earthquakes Canada uses the information its seismologists collect to help builders and emergency managers know what to expect for future events.
害羞草研究所淭hat害羞草研究所檚 really the goal of all the work that we do is to minimize the impact of earthquakes we may have in the future.害羞草研究所�
susie.quinn@albernivalleynews.com
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