Alaska Volcano Observatory

From Orr and others, 2024: "When the landscape near Aniakchak Crater is snow-free, and particularly when the ground has little moisture content, strong winds can pick up ash and create large ash clouds. The wind can then transport this resuspended ash, which can pose a hazard to aviation. On August 1-2, 2021, strong southerly winds entrained and resuspended ash from the region north of Aniakchak Crater and east of Port Heiden before carrying it ~200 km [~120 mi] northward over Bristol Bay. High-resolution satellite views indicated that the event’s source region was north of the caldera at the sparse surface exposures of pyroclastic-flow deposits from the caldera-forming eruption. The drifting ash cloud appeared in imagery from the Geostationary Operational Environmental Satellite for ~18 hours beginning late in the morning on August 1. Groundlevel webcam views from Port Heiden also recorded this resuspended ash. In response, AAWU issued a SIGMET for aviators and AVO issued an Information Statement. AVO received no reports of ashfall at Port Heiden. The Aviation Color Code and Volcano Alert Level remained GREEN and NORMAL for Aniakchak Crater during 2021."