Seismographs pick up ground shaking from powerful B.C. windstorm

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As a result of the strong wind Wednesday, seismographs in Victoria and Nanaimo picked up significant amounts of ground shaking.

John Cassidy, an earthquake seismologist with Earthquake Canada, says the wind caused trees, and buildings to shake which were picked up by seismographs.

“On Vancouver Island, you can see the shaking really increase all day today,” Cassidy said. “And really what all it is, is just the trees that are shaking so much, it’s buildings that are shaking, it’s ocean waves, and waves in lakes and inlets. So all of that comes together and just causes the ground to shake.”

Cassidy says this is something that happens when wind reaches 70-80 kilometers per hour, which happens about four times a year on Vancouver Island.

“We see it a few times a year, especially here on Vancouver Island. You see it in other places as well Newfoundland, and the east coast,” Cassidy said. “When there are hurricanes for example, in the southern U.S. you can clearly see the shaking from hurricanes as well. This sort of thing is recorded all around the world.”

While the seismographs were recording the ground shaking from the wind, Cassidy says there’s a possibility they masked smaller earthquakes.

“When it’s really noisy like this it hides the little earthquakes that might be happening,” he said. “So it’s really hard to see tiny, tiny earthquakes, little magnitude zeros or ones that are happening.”

He says while this shaking isn’t rare or unusual, it shows the different information that seismographs can be used for.

“The instruments that we have deployed to record earthquakes, record both small local earthquakes and large earthquakes around the world, but there are other things that we record as well,” Cassidy said. “There are a lot of different things that can make the ground shake, blasting and highway construction, wind storms, a lot of things can make the ground shake and these instruments that we use to record earthquakes are really really sensitive. So they’re picking up these minute shaking waves that you probably can’t feel.”

Laura Brougham

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