Thousands of tremors shaking under Vancouver Island 'out of the ordinary,' but likely not a threat

Scientists with the Pacific Northwest Seismic Network are monitoring an uptick in tremors shaking under Vancouver Island, but they don't believe them to be potential hazards or major tectonic shifts. 

The earthquake monitoring agency said tremors are normal, but starting Jan. 26, they started getting "stronger and longer." There were nearly 3,000 tremors reported by Tuesday afternoon. 

"It's important to keep in mind that 'ordinary' still isn't a very well understood term when it comes to tremor," the network said on Twitter. "We've been studying tremor for less than two decades, so what may seem irregular right now might be normal over the 300+ years since the last (Cascadia Subduction Zone) earthquake."

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Steve Malone, a retired University of Washington geophysics teacher, said it's his conclusion that most sections of the Cascadia Subduction Zone, which runs from Northern Vancouver Island to Cape Mendocino, California, see "slip" events like the one happening under Vancouver Island. 

The last Cascadia Subduction Zone earthquake happened in 1700. It was 1,500 times stronger than the magnitude 6.8 Nisqually earthquake that struck in 2001. 

The CSZ been relatively quiet for more than 300 years, but scientists and emergency preparedness officials have been warning Pacific Northwest residents for decades to be ready for the next "big one."