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Probing the pre-, syn-, and post-caldera: a field, micro-CT, and petrological study of Mt. Ijen volcano, Indonesia

Nicholas D. Barber^1^, Esti Handini2, Geika Pramana Surya2, Antonios Ratdomopurbo3, Allison Hidalgo1, Lillian Peskova1, India Balkaran1, Parker Comisac1,4, Gianmarco Buono5, Lucia Pappalardo5, Tantri Raya Ayuningtyas6, Kim Berlo7, Vincent van Hinsberg7

  • Affiliations: 1Department of Earth and Environmental Geoscience, Washington and Lee University, 204 W. Washington Street, Lexington, VA, USA 24450, 2Geological Engineering Department, Univeristas Gadjah Mada, Jl. Grafika No. 2, Kampus UGM, Yogyakarta, 55281, Indonesia, 3Sekretaris Badan Geologi, Kementerian Energi dan Sumber Daya Mineral, Jakarta, Central Jakarta 10110, Indonesia, 4Department of Geosciences, University of Arizona, Tuscon, AZ, USA, 85721 5Istituto Nazionale di Geofisica e Vulcanologia (INGV), Napoli, Italy 6Ijen Geopark,Bondowoso, East Java 68213, Indonesia, 7Geotop Research Centre, Department of Earth & Planetary Sciences, McGill University, 3450 University Street, Montréal, QC H3A2A7, Canada[Vv1]   [Vv1]if this is too long, you can drop the "Dept of EPS" 

  • Presentation type: Poster

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

  • Poster Board Number: 68

  • Programme No: 3.11.28

  • Theme 3 > Session 11

Abstract

Caldera-forming eruptions (CFEs) in Indonesia have produced some of the most destructive eruptions in history -- the Tambora eruption in 1815 being the most recent VEI-7 eruption in the historical record. The island of Java, home to most Indonesians, hosts several CFEs, including the Ijen Caldera Complex (ICC). Despite its large size (ca. 20 km in diameter) and relatively recent formation (between 300 and 50ka), it remains comparatively poorly understood. Kawah Ijen, ICC's active stratovolcano, hosts the world's largest acidic lake, where fumaroles emit globally significant quantities of sulfur and toxic metals into the surrounding environment. While being mostly quiescent today, the ICC experienced a phreatomagmatic eruption at Kawah Ijen as recently as 1817. North of the caldera, substantial ignimbrite deposits testify to the scale of the system and its eruptive potential. The age, duration, scale, and impact of this CFE are unknown, nor is the temporal evolution of the volcanic system post-CFE. To address these knowledge gaps, we present preliminary results of our 2024 field campaign, alongside our recent micro-computed tomography (micro-CT) measurements of erupted products from Kawah Ijen. We provide some of the first documented textural and geochemical descriptions of the ICC CFE, both in the field and under the microscope. Our micro-CT measurements allow us to provide the first estimates of magma ascent rates for Kawah Ijen's paroxysmal 1817 eruption. Together, these datasets provide a window in to how a complex and potentially dangerous caldera has evolved through time and allow for better assessment of future activity.