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Insights into the 2023 eruption of Shishaldin Volcano, Alaska, from satellite SO2 emissions and complementary datasets

Taryn Lopez1 , Peter Kelly2, Allan Lerner2, Dan Rasmussen, Mario Angarita1, Matt Loewen3, Valerie Wasser1, Skye Kushner4, Pablo Saunders-Shultz3, Christoph Kern2, Cindy Werner5, Ronni Grapenthin1, Israel Brewster1, Nicolas Theys6, Bruno Franco7, Lieven Clarisse7

  • Affiliations: 1University of Alaska Fairbanks Geophysical Institute, Alaska Volcano Observatory 2US Geological Survey, Volcano Emissions Project 3US Geological Survey, Alaska Volcano Observatory 4University of Alaska Anchorage 5US Geological Survey, Contractor 6Royal Belgian Institute for Space Aeronomy 7Université Libre de Bruxelles

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 281

  • Programme No: 3.17.43

  • Theme 3 > Session 17

Abstract

Shishaldin Volcano, Alaska, is a remote and frequently active basaltic stratovolcano that exhibits a range of eruption styles. Shishaldin's most recent eruptive period occurred between July and November 2023 and consisted of 13 explosive events with ash clouds reaching up to ~14 km altitudes. Given Shishaldin's remote location, TROPOMI satellite-derived SO2 emission measurements were a key parameter used by the Alaska Volcano Observatory to track volcanic activity during this eruption. Throughout most of the eruptive sequence, SO2 emissions were primarily associated with large explosions. However, during a 2-week period in October, SO2 plumes were detected daily in the absence of significant explosive activity as determined through seismic, infrasound and webcam observations. Based on gas compositions measured during a 2015 field campaign, and a Shishaldin-specific degassing model, we infer that substantial sulfur does not exsolve from Shishaldin's basaltic magma until depths of <3 km. This suggests that satellite SO2 observations can be used to track shallow magma ascent and degassing at Shishaldin. We use the cumulative SO2 mass emitted during the 2023 eruption (0.32 Mt) along with the melt S concentrations from the 1999 eruption (ΔS ~1500 ppm) to estimate a total dense rock equivalent volume of degassed magma of ~50 x 106m3. Comparing this result with the 2023 deflation volume (~10 x 106 m3), we estimate a ratio of eruptive to intrusive (degassed) magma of ~0.2. This case study highlights the utility of satellite SO2 data when combined with complementary datasets to inform eruptive processes, especially at remote volcanoes.