Mount St Helens

United States Forest Service

SKAMANIA COUNTY - Despite a surge of earthquakes at Mount St. Helens, officials at the United States Geological Survey it is nothing to be concerned about.

Four dozen earthquakes were reported at the stratovolcano but Dr. Weston Thelen with the USGS told KING 5 there is no sign that an eruption is on the horizon.

The volcano alert level hasn't been affected, but the increase in activity is a reminder that the volcano is the most active volcano in the Cascade Range.

Mount St. Helens was the last volcano to erupt, and is expected to be the next volcano to erupt.

“This is not a sign that an eruption is coming. These are small earthquakes located right above where we think the magma chamber is, it may mean magma is moving around, feeding into the chamber," Dr. Weston Thelen told KING 5 News.

A scientist at the Cascades Volcano Observatory says if there were more earthquakes a day or if they were larger, it could cause the alert level to rise.

“If they were larger or there were hundreds per day, that might cause a change to the alert level,” Dr. Seth Moran, scientist-in-charge at the Cascades Volcano Observatory told KING 5 News. “The two eruptions that we’ve watched happen both started with an incredible change in activity.”

The stratovolcano last erupted from 2004 to 2008, with a flock of small earthquakes occuring several times a year in the decades since the explosion. The earthquakes are predominantly between magnitude zero and one. Thelen said that small earthquakes are detected due to the all-inclusive monitor at Mount St. Helens.

“The reason we have that dense array is because Mount St. Helens is more active than the other Cascade volcanoes. But even if you’re hiking on the rim, you wouldn’t feel these small earthquakes happening three or four miles below the surface,” Thelen told KING 5 News.

Mount St. Helens exploded in May 19, 1980 and was the first time scientists witnessed what they call a "literal blast", or an eruption that blows out the side of the volcano as opposed to the top. Although earthquakes alerted scientists that an eruption was on the horizon, the lateral blast ended in 57 deaths and extensive widespread damage.

The volcano eruption was the deadliest eruption in United States history.

Mount Rainier, which is 59 miles south-southeast of Seattle, is far less active with about one earthquake per week. There is controversy about the last time Mount Rainier erupted amongst scientists, but Thelen explained it was in all likelihood 1,000 years ago.

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