(NewsNation) — A volcano in Alaska that last erupted in 1867 is displaying signs of rumbling.

About 140 miles southwest of Anchorage, Iliamna has remained inactive for more than a hundred years. However, on June 15, the Alaska Volcano Observatory noticed some seismic activity.

Experts suspect that this movement was probably due to a significant avalanche. Iliamna is notorious for its regular ice and rock slides, which result in the mountain shaking every few years.

While not a clear sign of imminent eruption, the event highlights the dynamic nature of this glacier-covered peak, which stands 10,000 feet tall.

As of July 4, Iliamna Volcano’s threat level is categorized as “Green/Normal,” according to the United States Geological Survey.