Debris-avalanche, volcanic avalanche, or landslide:
Not an eruption.
Description: AVO detected seismic and pressure sensor signals associated with a large avalanche on the flank of Iliamna Volcano around midnight Alaska Daylight Time (07:58 UTC May 22, 2016). Avalanche events are somewhat common at this volcano. The most recent prior to last night's occurred in November 2013. The seismic signals from the avalanche were observed on volcano monitoring networks throughout Cook Inlet and as distant as the Katmai region 250 km (155 miles) away. We have not received any visual observations of the slide location or extent, but the seismic data suggest that it is somewhat larger than recent avalanches. In the 12 hours since the event, there have been repetitive small glacial ice quakes. The avalanche and repetitive ice quakes are not considered to be indicative of volcanic unrest.