Semisopochnoi volcano (Aleutian Islands): Aviation Color Code reduced to Yellow

AVO reported ongoing low-level seismicity at Semisopochnoi characterized by intermittent seismic tremor and occasional low-frequency earthquakes during 16-22 November. Satellite and webcam views were mostly obscured by weather clouds, though during clear views continuous gas-and-steam emissions from the N crater of Mount Cerberus were visible. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch. ... Read all

On 7 November AVO stated that small explosions at the N crater of Mount Cerberus at Semisopochnoi had been detected in geophysical data during the previous week and volcanic tremor simultaneously resumed. Though ash emissions were not visually observed, the type of unrest was similar to previous periods associated with ash emissions below 3 km (10,000 ft) a.s.l.; the Aviation Color Code was raised to Orange (the second highest level on a four-color scale) and the Volcano Alert Level was raised to Watch (the second highest level on a four-level scale). Seismicity was low during 7-8 November, and clouds prevented webcam and satellite images. ... Read all