Aftershocks are continuing Morning morning after five earthquakes shook 200km off the west coast of Vancouver Island during the evening of Oct. 21.

B次元官网网址淚tB次元官网网址檚 not a surprise because this is one of the most seismically active parts of Canada,B次元官网网址� John Cassidy, a seismologist and professor at the University of Victoria, said the next morning.

B次元官网网址淲hat was different last night was to have three of this magnitude in 45 minutes.B次元官网网址�

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Tonight's M6.5-6.8 earthquakes ~200 km west of Vancouver Island were not felt by many people, but were easily recorded across from Victoria (VGZ) and Haida Gwaii (BNB) to Whitehorse, , and Halifax! Also recorded around the world.

B次元官网网址� John Cassidy (@earthquakeguy)

The shaking began at around 10:30 p.m., when three of the quakes were recorded within 45 minutes of each other at a magnitude of 6.6, 6.5, and 6.8. Two more quakes followed, measured at 4.9 and 4. While the shakes were felt in parts of the province, no injuries or damage has been reported.

B次元官网网址淭hey were easily recorded all across Canada, and in fact around the world,B次元官网网址� Cassidy said, adding that is typical of the magnitude. B次元官网网址淚f the earthquake is big enough the waves will circle the globe.B次元官网网址�

This type of earthquake, caused by strikes movement, doesnB次元官网网址檛 generally cause a tsunami because the shift is horizontal and not vertical. Sarah Hunn of the City of VictoriaB次元官网网址檚 emergency management team said they didnB次元官网网址檛 issue an alert on their subscription-based system because the Emergency Management BC and the national tsunami warning centre did not anticipate a tsunami. There were no alerts issued by the provinceB次元官网网址檚 automatic AlertReady system for these earthquakes. Usually, alerts are issued for events that require immediate action, such as evacuation.

At 470 km from Victoria, the earthquakes werenB次元官网网址檛 felt in the city only because of the distance. Cassidy pointed to a deadly earthquake in 2011 that killed 185 people in Christchurch, New Zealand, that was measured at a magnitude of 6.3 B次元官网网址� less than Oct. 21B次元官网网址檚 earthquakes off Vancouver Island. People can feel earthquakes at magnitude 3. By magnitude 4, the shaking is 10 times stronger. At 5, itB次元官网网址檚 100 times stronger.

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B次元官网网址淚tB次元官网网址檚 that distance that is making all the difference here, that theyB次元官网网址檙e several hundred kilometres away rather than 10 kilometres away like in Christchurch,B次元官网网址� Cassidy said.

While seismologists canB次元官网网址檛 predict when earthquakes will occur, they are studying where they will strike, how often and how large they will be. This information is used by engineers building and designing infrastructure in high seismic zones like Victoria.

B次元官网网址淚f we have a better understanding of what to expect in the future and our infrastructure is designed to withstand that level of shaking, then it doesnB次元官网网址檛 matter when an earthquake happens. Buildings survive and people know what to do. If weB次元官网网址檙e prepared then you really reduce the impacts of those future earthquakes,B次元官网网址� Cassidy said.

Cassidy said heB次元官网网址檒l be studying these earthquakes in the coming days and weeks.

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@KeiliBartlett
keili.bartlett@blackpress.ca

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