Long-range transport and microscopy analysis of Sangay volcanic ashes in Ecuador

Moran-Zuloaga, Daniel; Merchan-Merchan, Wilson; Rodriguez-Caballero, Emilio; Mulas, Maurizio; Hernick, Philip

doi:10.1007/s11869-023-01434-w

Cited by 6 publications

References 74 publications

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Developing hazard scenarios from monitoring data, historical chronicles, and expert elicitation: a case study of Sangay volcano, Ecuador

Bernard,

Tadini,

Samaniego

et al. 2024

Bull Volcanol

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Sangay volcano is considered as one of the most active volcanoes worldwide. Nevertheless, due to its remote location and low-impact eruptions, its eruptive history and hazard scenarios are poorly constrained. In this work, we address this issue by combining an analysis of monitoring data and historical chronicles with expert elicitation. During the last 400 years, we recognize periods of quiescence, weak, and enhanced eruptive activity, lasting from several months to several years, punctuated by eruptive pulses, lasting from a few hours to a few days. Sangay volcano has been mainly active since the seventeenth century, with weak eruptive activity as the most common regime, although there have also been several periods of quiescence. During this period, eruptive pulses with VEI 1–3 occurred mainly during enhanced eruptive activity and produced far-reaching impacts due to ash fallout to the west and long-runout lahars to the south-east. Four eruptive pulse scenarios are considered in the expert elicitation: strong ash venting (SAV, VEI 1–2), violent Strombolian (VS, VEI 2–3), sub-Plinian (SPL, VEI 3–4), and Plinian (PL, VEI 4–5). SAV is identified as the most likely scenario, while PL has the smallest probability of occurrence. The elicitation results show high uncertainty about the probability of occurrence of VS and SPL. Large uncertainties are also observed for eruption duration and bulk fallout volume for all eruptive scenarios, while average column height is better characterized, particularly for SAV and VS. We interpret these results as a consequence of the lack of volcano-physical data, which could be reduced with further field studies. This study shows how historical reconstruction and expert elicitation can help to develop hazard scenarios with uncertainty assessment for poorly known volcanoes, representing a first step towards the elaboration of appropriate hazard maps and subsequent planning.

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Developing hazard scenarios from monitoring data, historical chronicles, and expert elicitation: a case study of Sangay volcano, Ecuador

Bernard,

Tadini,

Samaniego

et al. 2024

Bull Volcanol

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Eruptive dynamics of open-vent andesitic volcanoes retrieved from petrological and componentry analysis of recent explosive phases (2020−2022) of Sangay (Ecuador)

Vizuete,

Samaniego,

Bernard

et al. 2025

Journal of Volcanology and Geothermal Research

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Probabilistic tephra fallout hazard maps for Sangay volcano, Ecuador

Tadini,

Pardini,

Bevilacqua

et al. 2024

Preprint

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We present a tephra fallout hazard assessment of Sangay volcano, Ecuador. This volcano is under semi-permanent activity at least since the 17th century, and has produced several eruptions whose products have affected towns and cities at considerable distance (up to > 170 km). For this reason, despite its remote location, recent efforts have been aimed at reviewing its volcanic history; quantifying the occurrence probability of various eruptive scenarios and the associated uncertainty; and, for each eruptive scenario, estimating the probability distribution of key eruptive source parameters (fallout volume, average plume height and eruption duration). In this study, we use this information to produce probabilistic hazard maps by using the coupled models PLUME-MOM-TSM and HYSPLIT, with the application of a novel workflow for running an ensemble of thousands of simulations following a stochastic sampling of input parameters. Probabilistic hazard maps have been produced for four scenarios of different magnitudes. For each scenario, we considered four ground load thresholds (0.1, 1, 10 and 100 kg/m2) and two types of model initialization strategies (based on the elicited total deposit volume and on the elicited plume height respectively), which produced non-negligible differences. Hazard curves have also been produced for nine sites of interest from a risk perspective, corresponding to towns/cities potentially affected by tephra accumulation. Combined maps have also been produced by merging maps of single scenarios with their probability of occurrence. Results indicate that in case of a future eruption, even for a moderate-scale eruption (Violent Strombolian), probability of tephra accumulation larger than 1 kg/m2 is relatively high (up to 20–25%) in the town of Guamote, i.e. the most severely affected site among those tested (43 km W of Sangay). For larger-scale events (Sub Plinian) the impact of tephra accumulation could be significant even for the city of Guayaquil (176 km W of Sangay), with probability of tephra accumulation larger than 1 kg/m2 up to 22%.

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Long-range transport and microscopy analysis of Sangay volcanic ashes in Ecuador

Cited by 6 publications

References 74 publications

Developing hazard scenarios from monitoring data, historical chronicles, and expert elicitation: a case study of Sangay volcano, Ecuador

Developing hazard scenarios from monitoring data, historical chronicles, and expert elicitation: a case study of Sangay volcano, Ecuador

Eruptive dynamics of open-vent andesitic volcanoes retrieved from petrological and componentry analysis of recent explosive phases (2020−2022) of Sangay (Ecuador)

Probabilistic tephra fallout hazard maps for Sangay volcano, Ecuador

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