Mount St. Helens has begun rumbling again! More than four decades after the worst eruption in U.S. history, this active volcano in Washington state is making headlines once more. Since February 1, 2024, around 350 earthquakes have been detected at Mount St. Helens by the Pacific Northwest Seismic Network. Most of these quakes—over 95%—have been less than magnitude 1.0, which means they’re too small to be felt. The largest recent quake was a magnitude 2.0 on May 31, 2024.
The big question on everyone’s mind: Could these earthquakes signal another massive eruption, like the catastrophic event in 1980 that claimed 57 lives and changed the landscape forever?
Mt. Saint Helens before and after its 1980 eruption pic.twitter.com/SCUFakCY3Q
— Benjamin Young Savage (ᐱᓐᒋᐱᓐ) (@benjancewicz) July 17, 2021
In early June, the weekly earthquake count peaked at 38, mostly occurring about 4.6 miles below the crater floor. Experts have detected magma moving through underground chambers, recharging the volcano. This activity follows a similar surge in 2023. According to the Cascades Volcano Observatory, “Short-term increases in earthquake rates are common at Mount St. Helens and are considered part of background seismicity.” The recent spikes in 2023 and 2024 represent the most significant increases since the last eruption ended in 2008. Yet, similar patterns of increased seismic activity from the late ’80s through the ’90s did not result in eruptions.
These earthquakes are primarily caused by the pressurization of the magma transport system, a process known as recharge. Magma from the lower crust bubbles up and accumulates in a reservoir 2.5 to six miles below the surface. When more magma enters this reservoir, it triggers quakes. Despite the seismic activity, there have been no significant changes in ground deformation, volcanic gas, or thermal emissions. So, the current hazard level at Mount St. Helens remains unchanged.
#OTD Mt. Saint Helens eruption. May 18th, 1980. pic.twitter.com/ghyTFifamj
— Michael Ferragamo (@FerragamoWx) May 18, 2021
Still, memories of the 1980 eruption loom large. On May 18, 1980, a magnitude-5 earthquake caused a massive eruption that blasted the volcano’s side off, creating a deadly landslide and a super-heated mix of ash, rock, and gas. This catastrophic event killed 57 people, obliterated miles of forest, and covered several states with volcanic ash. The aftermath saw 540 million tons of ash settle over seven states, disrupting life and causing significant environmental damage.
One poignant story from that day is of photographer Robert Landsburg, who, instead of fleeing, captured the eruption’s final moments on film were published in National Geographic.
Since then, Mount St. Helens erupted again from 2004 to 2008, giving scientists valuable insights and leading to advancements in monitoring technology. Today, 20 systems are in place to detect future eruptions, compared to just one in 1980.
