TY - JOUR
T1 - Pyroclastic deposits and eruptive heterogeneity of Volcán Antuco (37°S; Southern Andes) during the Mid to Late Holocene (<7.2 ka)
AU - Romero, J.E.
AU - Ramírez, V.
AU - Alam, M.A.
AU - Bustillos, J.
AU - Guevara, A.
AU - Urrutia, R.
AU - Pisello, A.
AU - Morgavi, Daniele
AU - Criollo, E.
N1 - Funding Information:
We thank to Dr. Brent V. Alloway for his detailed review and language assistance in the proof version of this manuscript. Authors are grateful to Mr. Hector Moyano, Mr. Luis Cortes and Dr. Juan D?az-Alvarado for their assistance and participation in the fieldwork. Dr. Urrutia thanks Conicyt/Fondap/15130015 research funding. The staff of Chile's National Forest Corporation (CONAF), Ana Hinojosa, Miguel Infante, Segundo Necul and Juan Bascur, provided excellent support for the fieldwork within the Laguna del Laja National Park. We thank the collaboration of the Chilean Army (Ej?rcito de Chile) and Chilean Police (Carabineros de Chile) to make the access possible to many of the remote areas and to provide accommodation facilities. Comments made by Drs. Silvina Guzm?n and Brian Jicha, plus the editorial handling of Dr. J.L. Mac?as, greatly improved the quality of this manuscript. This work is dedicated to Mr. Jes?s L?pez. Discussions and support of Drs. Tatiana Izquierdo, Manuel Abad, Hugo Moreno, Silke Lohmar, Gabriel Orozco, Daniel Melnick, Gustavo Villarosa and Edmundo Polanco significantly contributed to some interpretations. In memory of 44 young conscripts and a sergeant, who lost their lives on May 18, 2005 due to a sudden violent snow-storm during an irresponsible military exercise on the lower flanks of Volc?n Antuco.
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2020/2/15
Y1 - 2020/2/15
N2 - Volcán Antuco (37°24′ S, 71°22′W; 2979 m asl) is the 13th ranked high threat volcano in Chile with 27 recorded historical eruptions, mostly (~96%) with volcanic explosivity indices (VEI) of ~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 ~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.
AB - Volcán Antuco (37°24′ S, 71°22′W; 2979 m asl) is the 13th ranked high threat volcano in Chile with 27 recorded historical eruptions, mostly (~96%) with volcanic explosivity indices (VEI) of ~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 ~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.
KW - Active volcanism
KW - Southern Andes
KW - Strombolian
KW - Tephrostratigraphy
UR - http://www.scopus.com/inward/record.url?scp=85077470726&partnerID=8YFLogxK
U2 - 10.1016/j.jvolgeores.2019.106759
DO - 10.1016/j.jvolgeores.2019.106759
M3 - Article
SN - 0377-0273
VL - 392
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
M1 - 106759
ER -