PORTLAND, Ore. (KOIN) — Earthquake activity around Mount St. Helens spiked to nearly 350 quakes between February 1, 2024, and June 18, 2024, and officials say it may be a sign of “recharging” activity.
The increase in earthquake activity has only been small-magnitude quakes, but an increase nonetheless.
“Over the past several months, small magnitude earthquakes have been located at Mount St. Helens,” the Cascades Volcano Observatory said. “The seismicity is similar to what was observed at this volcano from July to December 2023. No significant changes have been observed in other monitoring parameters and there is no change in alert levels at this time. Mount St. Helens remains at normal, background levels of activity.”
According to an X post from the USGS Volcanoes, the seismic activity seen recently could mean the arrival of additional magma known as a process called “recharge.”
“Small magnitude earthquakes located beneath Mount St. Helens at depths well below sea level are generally thought to be associated with pressurization of the magma transport system. One cause for this pressurization is the arrival of additional magma, a process called recharge.”
The Cascades Volcano Observatory went on to explain that “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.”
The USGS Cascades Volcano Observatory says they will continue to monitor this activity and will provide any updates or warnings if warranted.
May marked 44 years since Mount St. Helens erupted, sending ash and debris across the Pacific Northwest. Fifty-seven people were killed in what is considered the deadliest volcanic eruption in the U.S.
Experts frequently note that earthquakes are simply part of what Mount St. Helens does. As Dr. Scott Burns, professor emeritus of engineering geology at Portland State University previously told Nexstar’s KOIN, Mount St. Helens has gone through “periods of coming back to life and then no activity, back to life and no activity” since its May 1980 eruption.
Burns, too, noted that magma is coming into Mount St. Helens’ crater in order to form the dome.
According to the USGS, Mount St. Helens is the second-most hazardous volcano in the U.S. behind Hawaii’s Kīlauea, which last erupted earlier this month.