Low-level eruptive activity at Semisopochnoi volcano has resumed over the past week. Small explosions have been detected in geophysical data during the past several days from the north crater of Mount Cerberus at Semisopochnoi, and volcanic tremor has also been observed. Ash emissions have not been seen in satellite imagery or web camera views. However, the type of unrest AVO detected was associated with ash emissions during previous periods of unrest and, if occurring, such ash emissions are likely lower than 10,000 ft above sea level. These events are similar to eruptive activity observed over the last year at Semisopochnoi, but not since September 14. For these reasons, AVO raised the Aviation Color Code and Volcano Alert Level to ORANGE/WATCH earlier today.

Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds usually under 10,000 ft (3 km) above sea level have characterized the recent activity. Small explosions and associated ash emissions could resume and may be difficult to detect during periods of high winds and/or when thick cloud cover obscures the volcano. Ash emissions over the past several years of activity have typically reached altitudes of less than 10,000 ft (3 km) above mean sea level. 

Semisopochnoi volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.

Low-level eruptive activity continues from a vent on the east flank of Pavlof Volcano, just below the summit. Volcanic tremor was observed in seismic data during the last 24 hours. Nothing significant was seen in mostly cloudy satellite images over the past day. Nothing of note observed in clear web camera views.

Small explosions associated with the current eruption could happen at any time and may be accompanied by small ash plumes within the immediate vicinity of the volcano. The level of unrest at Pavlof Volcano can change quickly and the progression to more significant eruptive activity can occur with little or no warning.

Pavlof Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.

Lava continues to erupt in the summit crater of Great Sitkin Volcano. Seismicity was low and nothing significant was observed in mostly cloudy satellite images over the past day. A few clear web camera views showed nothing of note.

Great Sitkin Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.

No local seismic activity was detected over the past day. Nothing significant was observed during the last 24 hours in cloudy satellite views of Mount Cleveland.

Episodes of lava effusion and explosions can occur without advance warning. Explosions from Mount Cleveland are normally short duration and only present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible but are less likely and occur less frequently.

When the seismic network is operational, Mount Cleveland is monitored by only three local seismic stations, which restricts AVO's ability to precisely locate earthquakes and detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.