Something wacky seems to be happening underneath Mount St. Helens.
Early today (Jan. 3), at least 17 earthquakes hit near the active volcano in Washington state, in rapid succession between 12:30am and 6:28am US Pacific time. The first and strongest registered a magnitude of 3.9 on the Richter scale, according to the Pacific Northwest Seismic Network.
Last month, University of Washington seismologists logged more than 80 quakes, a huge increase over the average 17 per month.
Mount St. Helens, 96 miles (154 km) south of Seattle, Washington and 50 miles (80 km) northeast of Portland, Oregon, is part of the Cascade Mountain Range that runs from northern California to British Columbia, Canada. It isn’t the only active volcano in the region—in fact, there are 12 other major volcanoes and nearly 3,000 other volcanic features in the Cascades—but scientists consider it the most active within the past 10,000 years.
Swarms of quakes around the Mount St. Helens are relatively common and do not always suggest a sign of impending eruption. Still, there have been a few instances in recent memory that have led the uptick in seismic activity to cause alarm.
The volcano’s most recent eruption, which occurred from 2004 to 2008, began with harbingers much like today’s: In the early hours of Sept. 23, 2004, a series of small-magnitude, shallow earthquakes rumbled through its lava dome. Over the next seven days, the frequency and size of the earthquakes increased and culminated in the first of several explosions on Oct. 1 2004. Fortunately, after initial steam and volcanic ash eruptions, the volcano only extruded semi-solid lava, which stayed relatively contained. By February 2008, the volcano quieted back down.
Mount St. Helens is most infamous for a 1980 eruption, which caused a horrifying level of devastation.
On May 18 that year, what had begun as tremors on March 20 culminated in a terrible explosion that blew off the volcano’s top 1,300 feet. The eruption caught the surrounding area unprepared and took the lives of 57, the deadliest volcanic event in US history. According to the US Geological Survey, most of the people who died likely did so from from asphyxiation after inhaling hot ash. Many of the victims’ bodies were also never found.
Presently, there seems to be no immediate danger of an eruption, according to geologist Trevor Nace, but scientists are continuing to monitor the situation. “While we can’t be certain,” Nace wrote in Forbes, “chances are the next time Mount St. Helen erupts, we will be significantly better prepared.”