Special Report: Experts Predict Another Volcanic Eruption In ... - KEZI

EUGENE, Ore. -- Volcanologists with the University of Oregon and the United States Geological Survey say an eruption similar to Mt. St. Helens will happen again in our lifetimes.

The last major eruption in the Cascades occurred on May 18, 1980, when Mt. St. Helens erupted.

Leif Karlstrom, a volcanologist with the University of Oregon, said the likelihood of a volcano eruption is very high.

"Mt. St. Helens has been very active in our lifetimes. If I were to put my money on a volcano erupting, I'd put it on Mt. St. Helens," said Karlstrom. "We will see another volcanic eruption in our lifetimes. I can't tell you when or where but statistically speaking we will."

A report done by the USGS back in 2018 highlights 161 volcanoes in the United States. They ranked the different volcanoes by very high risk, high risk, moderate, low, and very low. They rated 18 volcanoes as high risk, and eight of those are here in Oregon and Washington. Mt. St. Helens was number two on the list, with Mount Rainier number three, Mount Shasta number five, Mount Hood number six, and Three Sisters number seven.

Predicting when an eruption will happen is impossible, but volcanoes provide clues as towards when there could be an eruption.

"There are pretty clear precursors to many if not most volcanic eruptions. A volcano that's experiencing unrest will exhibit elevated seismicity, so small earthquakes. You'd see ground deformation, so the ground around the volcano swells up. Sometimes you see elevated gas emissions.," said Karlstrom.

The volcanoes in the cascades would erupt in one of two ways. Either there would be a blast of ash, rock, and debris, similar to the 1980 Mt. St. Helens eruption. Or they could have a gradual eruption where there is a slow flow of lava which travels long distances.

"The run-ups to eruptions can be days to weeks to months in some cases. So, typically we do have some warning," Karlstrom said.

This means unlike the next big earthquake which we talk about, volcanic eruptions typically provide some warning.