Swarm of small quakes at Mount Hood

Map shows an earthquake cluster on Mount Hood overnight Sunday into Monday morning - Photo from the Pacific Northwest Seismic Network

A so-called 'swarm' of earthquakes has showed up on Mt. Hood over the past twenty four hours on the south side of the mountain. According to scientists, it's the active volcano reminding all of us it's still around and there's no cause for concern.

Maps from the Pacific Northwest Seismic Network and the U. S. Geological Survey show quakes are happening frequently southeast of Timberline between there and Mt. Hood Meadows. They are small and shallow. The largest quake recorded since they started on Sunday is 1.9. The smallest quake in the swarm is a .3.

Portland State University Geology Professor Emeritus Scott Burns tells KATU News its unlikely humans will ever feel them unless they start getting to the 3.0 range.

"A whole bunch of earthquakes. Very small. One to two magnitude. A lot of them one right after another, we call a swarm," he said.

Burns has an idea about what's happening.

"If you get swarms under a working volcano, the working hypothesis is that magma is moving up into the, underneath there," he explained.

Burns said the swarms happen on Mt. Hood every few years. Its 900,000 years old.

"It last erupted in 1782. The time before that it was 1,500 years ago. It's an older volcanoAnd when you get to be older you're sporadic," he explained.

This swarm also has scientists excited because of recent, similar seismic activity at Mount St. Helens. They already know magma is forming there.

Burns said the number and frequency of the quakes on both mountains help scientists predict any sort of volcanic eruptions in a way they can't predict earthquakes.

"It just reminds us that we live in a geologically active area. Volcanoes do occur periodically. It may be related to an eventual eruption. If it is, we will know well in advance," he said.

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