The Alaska Volcano Observatory raised the alert level to advisory status for Tanaga Volcano on Tuesday following a series of earthquakes according to a report from Fox News.

“Earthquake activity beneath Tanaga Volcano began to increase slowly starting at about 1:30 p.m. AKST today. At roughly 8:45 p.m. AKST this evening, the activity escalated with earthquakes occurring as often as two or three each minute,” the office said in a Facebook post.

The largest of the quakes have magnitudes between 2.0 and 3.0, with initial locations at shallow depths beneath the volcano’s summit. “That indicates that we’re seeing significant unrest at the volcano,” John Power, a research geophysicist with the U.S. Geological Survey stationed in Anchorage at the Alaska Volcano Observatory, told The Associated Press.

“Whether or not this will lead to an eruption is something we can’t say at this point in time,” he noted. “But we are concerned about it enough that we have gone and elevated the warning level.”

Tanaga Volcano stands at 5,925 feet tall and is located in the western Aleutians. There are no communities or structures there, but Adak is about 65 miles away and could see ash fall.

The last known eruption for Tanaga was in 1914. If the volcano were to erupt, the biggest threat would be to aircraft. “It’s very different than what you would see, for example, in Hawaii, Kilauea or Mauna Loa, where you see these beautiful red rivers of lava flowing down the side of the volcano,” Power said.