On 4 September low-level ash emissions (less than 3 km or 10,000 ft a.s.l.) from Veniaminof were evident in webcam images and confirmed by observers in Perryville (35 km S), prompting AVO to raise the Aviation Color Code to Orange and the Volcano Alert Level to Watch.
Seismicity was elevated.
During 4-6 September pulsating, low-altitude ash plumes were visible from a Perryville webcam and reported by a pilot, and a small thermal anomaly was visible in satellite data.
On 7 September the thermal signal increased, suggesting lava fountaining at the summit.
Webcam images the next day showed minor ash or steam near the summit cone.
Ash deposits on the snowfield formed a ?V? shape from the summit, extending to the SSW and SE.
On 9 September a lava flow, about 800 m long, was identified on the S flank in satellite data.
Witnesses aboard a ferry passing Veniaminof early the next morning noted lava fountaining and an active lava flow.
Lava flows continued on 11 September, though were confined to the summit caldera.
Source: US Geological Survey Alaska Volcano Observatory (AVO)