Pyroclastic deposits and eruptive heterogeneity of Volcan Antuco (37°S; Southern Andes) during the Mid to Late Holocene (<7.2 ka)

Romero, Jorge E.Jorge E.RomeroRamírez, VictoriaVictoriaRamírezAlam, Mohammad AyazMohammad AyazAlamBustillos, JorgeJorgeBustillosGuevara, AliciaAliciaGuevaraUrrutia, RobertoRobertoUrrutiaPisello, AlessandroAlessandroPiselloMorgavi, DanieleDanieleMorgaviCriollo, EvelynEvelynCriollo2026-10-192026-10-192020-02Romero, Jorge E.; Ramírez, Victoria; Alam, Mohammad Ayaz; Bustillos, Jorge; Guevara, Alicia; Urrutia, Roberto; Pisello, Alessandro; Morgavi, Daniele; Criollo, Evelyn (2020-02). Pyroclastic deposits and eruptive heterogeneity of Volcan Antuco (37°S; Southern Andes) during the Mid to Late Holocene (<7.2 ka). JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 392, 106759. https://doi.org/10.1016/j.jvolgeores.2019.1067590377-02731872-6097https://hdl.handle.net/20.500.12740/25459Volcan Antuco (37 degrees 24' S, 71 degrees 22'W: 2979 m as!) is the 13th ranked high threat volcano in Chile with 27 recorded historical eruptions, mostly (similar to 96%) with volcanic explosivity indices (VEI) of similar to 1-2. An older eruptive record has been reconstructed from sections exposed on the western flank and is intimately related to a well-documented catastrophic sector collapse at similar to 7.2 cal ka BP. However, very little is known about Antuco's post-collapse eruptive history in other sectors, especially on the eastern flanks where prevalent westerly winds favor optimal eastward tephra transport and deposition. Our study reveals a more complete record of activity that has already been indicated from previous work with at least 23 tephra-forming explosive eruptions, most of them within the last c. 7.2 ka, including 4 events that have generated pyroclastic density currents that have widely inundated the lower eastern flanks. Tephra from these eruptive events are typically composed of scoria, free crystals and lithics, with occasional pumice. The composition of juvenile fragments varies between basalt and trachyandesite (50.2-62.2 wt% SIO2) and show phenocrysts of plagioclase, olivine and pyroxene. Our results show that most of the eruptions of Antuco (c. 79%) are Strombolian to violent Strombolian. These eruptions have an estimated longer repose times (c. 200 year) and are likely higher in magnitude than those registered during historical times. This study also shows that the composition, style and magnitude may change from one eruptive episode to the next. This eruptive variability seems in complete accord with recent findings from other centers in the Southern Volcanic Zone exhibiting similar temporal eruptive diversity and ultimately, has significant implications with respect to hazard assessment. (C) 2019 Elsevier B.V. All rights reserved.enActive volcanismTephrostratigraphyStrombolianSouthern AndesPyroclastic deposits and eruptive heterogeneity of Volcan Antuco (37°S; Southern Andes) during the Mid to Late Holocene (<7.2 ka)Articulohttps://doi.org/10.1016/j.jvolgeores.2019.106759