Seismic activity in Alaska’s Aleutian Islands heralds a higher chance of volcanic eruptions

Scientists at the Alaska Volcano Observatory issued a warning Thursday that two volcanoes in the state’s Aleutian Islands archipelago could erupt after recent seismic activity.

At 5:22 p.m. local time Thursday, the observatory sent out an alert, noting that earthquake activity had increased in the vicinity of the Takawangha volcano over the previous 48 hours. This, scientists said, could presage a volcanic eruption.

Seismic activity was also heightened at the Tanaga volcano, 5 miles west of Takawangha in the western part of the Aleutian Islands. Scientists are unable to determine which volcano would erupt.

As of Thursday night, several small earthquakes were rumbling under Tanaga per minute. The largest seismic event within 24 hours of the AVO alert was a magnitude 3.9 earthquake under Tanaga.

Tanaga’s most recent eruption was in 1914, with none recorded for Takawangha. However, given their proximity, scientists say historic eruptions previously attributed to Tanaga, such as those in 1763, 1770, 1791 and 1829, could have come from Takawangha instead.

If either volcano erupts, the closest community affected would be Adak, 65 miles from the volcanoes. The town of around 170 would experience ashfall.

Air travel could also feel the impact. The Aleutian Islands are located beneath plane routes between Asia and North America, and sharp volcanic ash can shut down aircraft engines.

Past eruptions recorded at the volcanoes had large ash clouds and slow-moving lava flows similar to the 1980 Mount St. Helens eruption, according to The Associated Press.

It is also possible that the earthquakes abate without an eruption occurring.

“Whether or not this will lead to an eruption is something we can’t say at this point in time. But we are concerned about it enough that we have gone and elevated the warning level. It’s anybody’s guess as to where this particular round of earthquake activity may end up,” John Power, a U.S. Geological Survey geophysicist stationed at the AVO, told the AP.