Satellite observations of the 2016–2017 eruption of Bogoslof volcano: aviation and ash fallout hazard implications from a water-rich eruption
Satellite data (GOES, VIIRS, MODIS, AVHRR) were used in near real-time during the 2016–2017 eruption of Bogoslof volcano, Alaska, to detect explosive eruptive activity and to characterize the resulting volcanic clouds. This study examines satellite data to estimate volcanic cloud heights and mass eruption rates for 47 of the 70 explosive events. Eighteen of the volcanic clouds reached an altitude in excess of 8.5 km asl, where they posed a potential hazard to aviation. We estimate eruption rates were in the range of 104–107 kg/s. Eruption durations were available for 28 events, and the total mass of these events was 5.7 × 1010 kg. Most of the explosions occurred from submarine vents, producing volcanic clouds with water-rich characteristics in satellite data. We infer that these water-rich (phreatomagmatic) events contained ice-coated ash particles, which changed their visible and multispectral characteristics. Only two of the explosions produced clouds with satellite characteristics that would be considered ash-rich. We conclude that these events were relatively dry eruptions with limited access to ocean water. Although some of the explosive events transitioned from submarine to subaerial vents, we observed no change in the character of the volcanic clouds during these transitions. We speculate that enhanced removal of fine-grained volcanic ash likely occurred due to aggregation, with implications for modeling ash transport and fallout. We conclude that the majority of Bogoslof’s water-rich volcanic clouds did contain volcanic ash despite the lack of conventional “ash signature” in satellite data. This has implications for satellite monitoring of future water-rich/shallow submarine eruptions.