Washington’s ‘Forgotten Giant’ Volcano Stirs: Surge in Quakes Prompts Increased Monitoring

There’s been some unusual rumblings coming from Mount Adams, but for those in the area, it’s not time to panic. Geologists are closely monitoring Washington’s largest volcano (and second tallest mountain), which hasn’t erupted since the Bronze Age.

During the month of September, the United States Geological Service detected six earthquakes at the mountain. That’s unusually high, given that Mount Adams typically experiences just one earthquake every two or three years. In fact, it’s the most quakes detected in the area within a single month since 1982. The shakes spurred the USGS to increase the number of sensors they have deployed in the area, to determine whether the quakes are a sign of an impending eruption.

The six quakes were all relatively minor, with none exceeding 2.0 on the Richter scale. The seismic activity was not felt at the surface and was only detected because of a seismic station located seven miles away from Mount Adams’ summit. While it’s understandable that this could be a tad nerve wracking, geologists who study the area said it’s not yet clear if the increase in seismic activity is anything more than just an unusually high number of tremors.

“We are now working to gather more data to assess if this is really something unusual or just a volcano talking to us a bit more than it normally does,” Jon Major, the scientist-in-charge at the USGS’ Cascades Volcano Observatory, told LiveScience.

In a statement, the USGS stressed there is not yet any cause for alarm. The USGS uses a four-tiered alert system for volcanoes, and Mount Adams’ status remains at normal, the lowest level, where a volcano is deemed to be in a “typical background, noneruptive state.”

To see if that remains the case, the USGS received permission from the U.S. Forest Service to install additional, temporary seismic monitoring stations to the south and southwest of Mount Adams. This measure “will improve our ability to locate smaller earthquakes with more certainty and assist in understanding the cause of these earthquakes,” the USGS said. “The results of our findings will determine if any additional actions are needed.”

Typically, earthquakes at Mount Adams are located at a rate of about 1 earthquake every 2-3 years. USGS is adding extra monitoring stations.

This is a good reminder that Adams is one of our state’s FIVE active volcanoes. It’s also worth noting that it still remains green/normal https://t.co/NYgh3srb85

— WA Emergency Management (@waEMD) October 3, 2024

With a height of 12,281 feet (3,743 meters), Mount Adams is shorter than Mount Rainier, but is larger by volume. It’s been around 3,800 years since Mount Adams, known as Washington’s “forgotten giant,” last erupted, but that doesn’t mean the volcano is dormant. In fact, the USGS classifies Adams as a “high-threat volcano,” a term that refers more to the implications of an eruption on nearby populations and infrastructure, as well as aviation in the area, than to the actual likelihood of an eruption. Geologic data shows that past eruptions of the volcano have mainly involved lava flows traveling only a few miles, with relatively little explosive activity.

There’s an obvious precedent for a seemingly quiet American volcano suddenly springing back to life. In 1980, Mount St Helens, also located in Washington, erupted, killing 57 people, and continued to display volcanic activity until 2008. Even if the Mount Adams seismic activity is evidence of an impending eruption, it’s unlikely something so spectacular will take place. The USGS said the biggest threat facing people near Mount Adams are flows of rock, ash, and ice, called lahars. Lahars can occur whether the volcano is erupting or not, and can move quickly, giving those in their way little time to clear out.

Once again, it’s not time to freak out. While it’s possible this will be Mount Adams’ first eruption since construction of the Great Pyramid of Giza began (give or take a century or two), this could all be nothing more than the seismic equivalent of a grumbly tummy.