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Small-scale phreatomagmatic eruptions as precursors of larger caldera-forming eruptions: Insights from Acigöl caldera, Central Anatolia (Turkey)

^^Ivan Sunyé-Puchol1^^ , Xavier Bolós2, Rengin Özsoy1, Efe Akkaş3, Lorenzo Tavazzani4, Manuela Nazzari5, Olivier Bachmann4, Piergiorgio Scarlato5,  and Silvio Mollo1,5

  • Affiliations: 1Department of Earth Sciences, Sapienza University of Rome, 00185 Rome, Italy, 2Geosciences Barcelona, GEO3BCN-CSIC, 08028 Barcelona, Catalonia, Spain 3Department of Geological Engineering, Hacettepe University, 06800, Ankara, Turkey 4Department of Earth Sciences, ETH Zurich, CH-8092, Zurich, Switzerland 5Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Roma1, 00143, Rome, Italy

  • Presentation type: Talk

  • Presentation time: Thursday 15:45 - 16:00, Room S160

  • Programme No: 3.7.5

  • Theme 3 > Session 7

Abstract

The Acigöl caldera (Cappadocian region, Turkey) offers a compelling case study of how small-scale, monogenetic-type eruptions, can initiate cascading volcanic processes culminating in large-scale, caldera-forming events. A detailed tephrostratigraphic analysis of a key outcrop within the Acigöl caldera, supported by glass chemistry and geochronological data, reveals a continuous sequence of volcanic deposits --- including a debris avalanche, tephra ring, plinian fall, ignimbrite, and lava dome --- indicative of rapid, successive eruptions without significant hiatuses. This study highlights how minor phreatomagmatic events, such the Taskesik maar, can serve as the initial trigger in a sequence of eruptions that ultimately lead to caldera roof collapse. This progression includes a Plinian phase along caldera ring fractures, which depressurizes the magma chamber and facilitates the subsidence of lithospheric blocks. Our findings underscore the importance of recognizing small-scale eruptions as potential precursors to major caldera-forming events, emphasizing their significance for improving hazard assessment strategies in active caldera systems, particularly those in densely populated areas such the turistic region of Cappadocia. This study has been funded by the the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Actions (PÜSKÜRÜM project, grant #101024337), and the Spanish Ministry of Science and Innovation under TURVO project PID2023-147255NB-I00, supported by MCIU, AEI (10.13039/501100011033), and FEDER, EU.