Small earthquake reported in Vancouver

A small earthquake stirred under west Vancouver on Monday morning, according to the U.S. Geological Survey.

The 2.7-magnitude tremor was measured near Vancouver Lake at a depth of 19.3 kilometers, according to USGS. The quake occurred at 8:31 a.m.

No damage was reported, and no emergency calls resulted from the quake, according to the Clark Regional Emergency Services Agency. But a handful of people in the Vancouver area did log onto a USGS website to report that they had felt it. All of them categorized any shaking they felt as weak.

Mainly, Monday’s temblor served as a reminder that the Northwest is a seismically active area, said John Vidale, director of the Pacific Northwest Seismic Network in Seattle. Years of data show that has been the site of other earthquakes in the past, he said. That included a smaller 1.1-magnitude tremor — too small to feel — recorded later Monday morning.

“Over the last few decades, we’ve had earthquakes as big as the mid-3s right about there,” Vidale said, referring to magnitude. “Today’s was just the latest in a line of earthquakes.”

It’s relatively common for small quakes to spring from “microfaults” that criss-cross the entire region. The depth of Monday’s quake suggests it was tectonic, Vidale said. That means it was caused by the squeezing or grinding of plates, not volcanic activity or something human-made.

The quake also fell within a magnitude range that was strong enough to feel, but easy to miss, Vidale said.

“Anything below a 2.5 would be hard to feel,” he said. “Anything above a 3.5, you’re probably going to feel unless you’re distracted.”

In January 2013, a 3.7-magnitude earthquake centered near Amboy was widely felt in the Portland-Vancouver area. Two years earlier, on Valentine’s Day in 2011, a 4.3-magnitude earthquake shook near Mount St. Helens.

The Pacific Northwest Seismic Network has recorded dozens of earthquakes across the region in just the past two weeks, most too small to notice. Many of the area’s tremors are concentrated near volcanoes — Mount St. Helens, for example, has seen 23 earthquakes in the past 30 days, according to the agency.

All of that pales in comparison to the catastrophic earthquake that scientists expect to be unleashed by the Cascadia Subduction Zone fault someday. “The big one” could be a 9.0-magnitude monster that causes widespread damage across the region, Vidale said. The Cascadia fault sits off the coast, and stretches from Vancouver Island to California.