Increased Tremors Cause Increased Vigilance

There have been strange rumblings coming from Mount Adams, but for those in the area, it’s not time to panic. Geologists are keeping a close eye on 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 on the mountain. That’s unusually high, given that Mount Adams typically experiences one earthquake every two or three years. In fact, it’s the most earthquakes in the area in one month since 1982. The quake has prompted the USGS to increase the number of sensors it has installed in the area, to see if the tremors are a sign of an imminent eruption.

The six earthquakes were all relatively minor, none exceeding 2.0 on the Richter scale. Seismic activity was not felt at the surface and was only detected because of the seismic station located 7 miles from the summit of Mount Adams. While it is understood that this could cause disturbances, geologists studying the area said it is not yet clear that the increase in earthquakes is more than just an unusually high number of tremors.

“Now we’re working to collect more data to test whether this is really an anomaly or if the volcano is talking to us less than it normally does,” Jon Major, chief scientist at the USGS’ Cascades Volcano Observatory, told LiveScience.

In a statement, the USGS emphasized that there is no reason to panic. The USGS uses a four-tier warning system for volcanoes, and Mount Adams’ status remains abnormal, the lowest level, where the volcano is considered a “normal, non-catastrophic site.”

To ensure that remains the case, the USGS has received permission from the US Forest Service to install additional, temporary earthquake monitoring stations south and southwest of Mount Adams. The measurement will “improve our ability to detect small earthquakes with greater certainty and help understand the cause of these earthquakes,” the USGS said. “The results of our findings will determine whether further action is needed.”

Generally, earthquakes in Mount Adams occur at a rate of 1 earthquake every 2-3 years. The USGS is adding more monitoring stations.

This is a good reminder that Adams is one of FIVE active volcanoes in our state. It is also important to note that it is still green/normal

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

At 12,281 feet (3,743 meters), Mount Adams is shorter than Mount Rainier, but larger in volume. It’s been about 3,800 years since Mount Adams, known as Washington’s “forgotten giant,” last erupted, but that doesn’t mean the volcano is gone. In fact, the USGS classifies Adams as a “high-risk volcano,” a term that refers more to the effects of an eruption on nearby communities and infrastructure, as well as aviation in the area, rather than the actual likelihood of an eruption. Geologic data show that the volcano’s past eruptions involved mostly lava flows that traveled only a few kilometers, with relatively small eruptions.

There is an obvious precedent for a seemingly dormant American volcano suddenly springing to life. In 1980, Mount St Helens, also in Washington, erupted, killing 57 people, and continued to show volcanic activity until 2008. Even if the Mount Adams earthquake is evidence of an impending eruption, it is unlikely that something so spectacular will happen. The USGS said the biggest threat facing people around Mount Adams is flows of rock, ash, and snow, called lahars. Lahars can occur whether the volcano is erupting or not, and can move quickly, giving those in the path little time to evacuate.

Again, this is not the time to panic. While this will likely be the first eruption of Mount Adams since the construction of the Great Pyramid of Giza began (give or take a century or two), this may all be the earthquake equivalent of a grumbling stomach.