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Volcanic lightning and plume dynamics during the 2023 eruption of Shishaldin Volcano, Alaska: Insights from a dry, coarse-grained, basaltic eruption

Rui Mota 1, Alexa R. Van Eaton2, Larry G. Mastin2, David J. Schneider3, Hanna Dietterich3, Matthew Loewen3, José Pacheco1, Artur Gil1

  • Affiliations: 1) Research Institute for Volcanology and Risk Assessment (IVAR), University of the Azores, 9500-321 Ponta Delgada, Azores, Portugal. 2) U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, Washington, USA 3) U.S. Geological Survey, Cascades Volcano Observatory, Anchorage, Alaska, USA

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 98

  • Programme No: 3.12.24

  • Theme 3 > Session 12

Abstract

Shishaldin Volcano, Alaska, USA, produced 13 eruptive events from July to November 2023, with plume heights ranging 3--14 km above sea level. Eight of the plumes reached an altitude ≥9 km, threatening aviation. Communities, airports, and marine vessels reported ashfall. The tephra deposits were basaltic and predominantly coarse-grained, although co-pyroclastic density current plumes also deposited fine-grained ash. This was a dry eruption (minimal magma-water interaction), with several plumes producing low-moderate rates of volcanic lightning up to 2--3 lightning pulses/min. Here, we investigate how changes in mass eruption rate (MER) and atmospheric conditions influenced the plume and lightning characteristics. We use Vaisala's GLD360 lightning dataset, GOES-18 satellite observations, global data assimilation system (GDAS) meteorological data, and the one-dimensional steady-state plume model, Plumeria, to constrain source parameters for each event. Our results indicate that peak MER was ~2x107 kg/s (event 11), and the 13 eruptive events produced a total volume of 0.05 km3. Atmospheric analysis shows that wind speed significantly decreased the height of the observed plumes. Volcanic lightning occurred mainly in events with MER >106 kg/s, when the plume height reached above the atmospheric freezing level (approximately -20°C). We conclude that a combination of triboelectrification and ice charging dominated in this dry eruption, given the paucity of mixed-phase microphysics (ice + liquid water) in the plume models. During event 10, lightning data revealed that the plume continued for several hours below the cloud deck, where it was not detectable by satellite, highlighting the value of lightning to assist volcano monitoring.