Semisopochnoi volcano (Aleutian Islands, USA) - Smithsonian / USGS Weekly Volcanic Activity Report for 8 September-14 September 2021 (Continuing Activity)

AVO reported that eruptive activity at Semisopochnoi's North Cerberus crater continued during 7-14 September. Seismicity was elevated and characterized by periods of continuous tremor. Short-lived explosions lasting several minutes were detected daily in infrasound data.
Small ash clouds from the explosions rose 3-4.6 km (10,000-15,000 ft) and dissipated within two hours. Sulfur dioxide emissions were detected in satellite images at altitudes less than 3 km (10,000 ft) a.s.l., sometimes extending downwind for hundreds of kilometers. During 7-9 September periods of lower-altitude ash emissions interspersed with voluminous steam plumes were observed in web camera images moving horizontally by the wind and rising no higher than 1.5 km (5,000 ft) a.s.l.
The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
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From: Global Volcanism Program, 2021. Report on Semisopochnoi. In: Mayberry, G (ed.), Weekly Volcanic Activity Report 8 September-14 September 2021. Smithsonian Institution and US Geological Survey.