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WITHDRAWN -Modeling Magma Recharge Dynamics during the 2016 Nevados de Chillán Eruption: Insights from a Two-Chamber Interaction System through Petrology and Geodesy

Camila Novoa Lizamaa, D. Remyb, J.C. Baezc, A. Oyarzund, S. Bonvalotb, A. Hoopera

  • Affiliations: a COMET, School of Earth and Environment, University of Leeds, Leeds, UK. b GET/UMR5563 (UPS, CNRS, IRD, CNES), Obs. Midi-Pyrénées, Université P. Sabatier, Toulouse, France. c Centro Sismológico Nacional, Universidad de Chile, Santiago, Chile. d Dirección de Desarrollo e Innovación, Universidad de Concepción, Victor Lamas 1290, Concepción, Chile. 

  • Presentation type: Talk

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

  • Programme No: 1.8.7

  • Theme 1 > Session 8

Abstract

The Nevados de Chillán volcanic complex in southern Chile experienced a six-year eruption. During the first three years, phreatic and phreato-magmatic activity occurred without surface deformation. In June 2019, an effusive phase began, marked by an uplift episode. This study analyzes surface displacements from 2015 to 2022 using InSAR and GNSS data, integrated with petrological, geochemical, geophysical, and field observations, proposing that deformation was driven by magma recharge between two reservoirs beneath the volcano. Our model, combining analytical and boundary element methods, accounts for reservoir geometries and topographic effects on surface displacements. Results indicate a shallow elongated reservoir (5.8 km depth) connected to a deeper sill-type reservoir (15 km depth) via a magma-filled conduit. An initial small magmatic intrusion likely activated the system by overheating the hydrothermal system, explaining the lack of deformation during the phreatic phase, followed by magma mobilization causing minor subsidence during the phreato-magmatic phase. In June 2019, a larger magma intrusion triggered uplift, decaying exponentially over three years, driven by a constant magma influx of 0.016 km³/year into the deeper reservoir. This dynamic recharge model explains mafic enclaves in erupted dacites and integrates geophysical, petrological, and geochemical observations. It offers insights into eruptions and uplift episodes in volcanoes with interconnected magma chambers, advancing our understanding of pre-, co-, and post-eruptive magma recharge processes.