Mount St. Helens: Seismic activity brewing with more than 350 earthquakes since February

Jun 24, 2024, 12:12 PM | Updated: 2:53 pm

mount st. helens earthquakes...

Horseshoe-shaped crater on top of Mount St. Helens after a major eruption on May 18, 1980. (Photo: R. Lamb, Getty Images)

(Photo: R. Lamb, Getty Images)

Mount St. Helens has been stirring as of late, showing increased signs of seismic activity over the last few months, according to the U.S. Geological Survey.

The volcano has experienced 368 earthquakes since the beginning of February with 38 alone occurring in the first week of June.

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The recent seismic activity is the largest short-term increase in earthquakes since the volcano last erupted in 2008. But more than 95% of the earthquakes have been less than 1.0 magnitude — too small to be felt on the surface.

Small earthquakes beneath volcanoes like Mount St. Helens are generally thought by scientists to be part of a recharge process where magma builds up beneath the volcano, according to the U.S. Geological Survey.

“Mount St. Helens is fed by magma that forms near the base of the crust at depths of about 16 miles (25 kilometers),” the U.S. Geological Survey stated. “Magma slowly rises through the lower crust and accumulates in a reservoir about 2.5 to 6 miles (4‒10 km) below sea level. Recharge events can occur when magma enters this upper reservoir and increases stresses that lead to earthquakes.”

More on Mount St. Helens: Small earthquake felt near Mt. St. Helens

Magma recharges have been observed in the past at Mount St. Helens and can continue for many years without an eruption.

“There have been no significant changes in other monitoring parameters (ground deformation, volcanic gas or thermal emissions) and no change in hazards at Mount St. Helens as a result of this activity,” the U.S. Geological Survey added.

More on Mount St. Helens

Frank Sumrall is a content editor at MyNorthwest. You can read his stories here and you can email him here.

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Mount St. Helens: Seismic activity brewing with more than 350 earthquakes since February