Aleutian Islands' Shishaldin volcano being watched following increase in seismic activity overnight

© Dane Ketner / AVO

View of Shishaldin from an Alaska Volcano Observatory monitoring site on the southwest flank of the volcano on June 28, 2014. The upper flanks of the volcano are darkened by ash erupted during low-level lava fountaining and small explosions deep in the summit crater.

The Aleutian Islands' Shishaldin volcano was being watched Monday morning following an increase in seismic activity overnight.

The Alaska Volcano Observatory posted a "watch" alert due to the increase in activity, which suggests "that the eruption at Shishaldin has intensified," AVO wrote. Elevated surfaces temperatures were shown on satellite images near the volcano's summit.

Shishaldin, elevation 9,373 feet, is located on Unimak Island on the Aleutians. The volcano has been listed as "orange" for months, coordinating scientist with the Alaska Volcano Observatory Jeff Freymueller said, as small explosions within Shishaldin's crater have been occurring "pretty much all the time."​ The color code "orange" indicates an ongoing level of heightened activity at a volcano.

These small explosions within the volcano are likely to continue for "some time," Freymeuller said, bringing along the "potential that at any moment ... you could have a much bigger (explosion)."

On Sunday night, seismic activity was vacillating, increasing and declining again, Freymueller said.

On Monday morning, thermal sensing data suggested that hot material had likely been emitted from the volcano, Freymueller said, but what kind of material and how much had been emitted was unclear.

The volcano can be viewed with the Alaska Volcano Observatory's webcam.