Geology topics

Felipe Aguilera

Publications and source records attributed to Felipe Aguilera.

3 recordsLinked to original sources

USGS2025

Origins and fluxes of gas emissions from the Central Volcanic Zone of the Andes

We present geochemical data from gas samples from ∼1200 km of arc in the Central Volcanic Zone of the Andes (CVZA), the volcanic arc with the thickest (∼70 km) continental crust globally. The primary goals of this study are to characterize and understand how magmatic gases interact with hydrothermal systems, assess the origins of the major gas species, and constrain gas emission rates. To this end, we use gas chemistry, isotope compositions of H, O, He, C, and S, and SO 2 fluxes from the CVZA. Gas and isotope ratios (CO 2 /S T , CO 2 /CH 4 , H 2 O/S T , δ 13 C, δ 34 S, 3 He/ 4 He) vary dramatically as magmatic gases are progressively affected by hydrothermal processes, reflecting removal and crustal sequestration of reactive species (e.g., S) and addition of less reactive meteoric and crustal components (e.g., He). The observed variations are similar in magnitude to those expected during the magmatic reactivation of volcanoes with hydrothermal systems. Carbon and sulfur isotope compositions of the highest temperature emissions (97–408 °C) are typical of arc magmatic gases. Helium isotope compositions reach values similar to upper mantle in some volcanic gases indicating that transcustal magma systems are effective conduits for volatiles, even through very thick continental crust. However, He isotopes are highly sensitive to even low degrees of hydrothermal interaction and radiogenic overprinting. Previous work has significantly underestimated volatile fluxes from the CVZA; however, emission rates from this study also appear to be lower than typical arcs, which may be related to crustal thickness.

Central Volcanic Zone of the Andes↗

USGS2023

A new permanent, low-cost, low-power SO2 camera for continuous measurement of volcanic emissions

Since its introduction to volcanology in the mid-2000 s, the SO 2 camera has become an important instrument for the acquisition of accurate and high time-resolution SO 2 emission rates, aiding in hazard assessment and volcanological research. However, with the exception of a few locations (Stromboli, Etna, Kīlauea), hitherto the majority of measurements have been made on discrete field campaigns, which provide only brief snapshots into a volcano’s activity. Here, we present the development of a new, low-cost, low-power SO 2 camera for permanent deployment on volcanoes, facilitating long-term, quasi-continuous (daylight hours only) measurements. We then discuss preliminary datasets from Lascar and Kīlauea volcanoes, where instruments are now in continuous operation. Further proliferation of such instrumentation has the potential to greatly improve our understanding of the transient nature of volcanic activity, as well as aiding volcano monitoring/eruption forecasting.

Frontiers in Earth Science↗

USGS2020

Combining ash analyses with remote sensing to identify juvenile magma involvement and fragmentation mechanisms during the 2018/19 small eruption of Peteroa volcano (Southern Andes)

The Planchón Peteroa Volcanic Complex (PPVC) is located on the border of Chile and Argentina, and is one of the most active volcanic systems in the Andes. Holocene activity has included magma-water interaction with an evolving series of crater lakes, mainly sourced from Peteroa volcano. This study examines data from the 2018/19 eruption, together with the volcanic history of the PPVC, to elucidate the complex interplay between magmatic activity and summit water and ice. From February 2016 to mid-2019, three seismic swarms occurred in the PPVC, preceding the explosive eruption from September 2018 to April 2019. The activity originated from a small vent nested within the easternmost crater, the most active portion of the complex (Peteroa). The explosions interacted with a crater lake, producing ash plumes up to 2 km above the crater and building a small tephra cone. To investigate the eruption mechanisms, we performed remote sensing analysis of plume dispersal, thermal anomalies and ground deformation, and characterized the volcanic products, including grain size, componentry, morphology, internal textures, composition and mineralogy. Our results suggest that the precursory seismicity beginning in 2016 was related to the intrusion of a new magma batch that reached the surface during the 2018/19 eruption. The eruption was also preceded by thermal anomalies, geomorphic changes and increased hydrothermal activity at the surface, though without any ground deformation recognized through radar interferometry (InSAR). The eruption initially produced predominantly recycled ash (phreatic activity), then evolved to increasing proportions of juvenile magma (phreatomagmatic) by April 2019. The juvenile clasts had a trachyandesite composition (~59 wt% SiO 2 ), with vesicular and dense scoria containing plagioclase and pyroxene. The ash surfaces show external quenching cracks and step fractures consistent with phreatomagmatic fragmentation within the active crater lake. Textural characteristics also point to a slowly ascending batch of magma that was relatively viscous by the time it interacted with water in the crater lake. Notably, these juvenile particles are distinctive from the pre-2018 products. Ash erupted from 2010/11 did not contain recognizable juvenile material, and is inferred to have been a mainly phreatic eruption. Our findings suggest that the interplay between phreatic and phreatomagmatic eruptions fed by small magma batches intruding at shallow levels characterize much of the eruptive behavior of the PPVC during the last three decades. Multi-parametric assessment is a powerful tool to discriminate between phreatic and phreatomagmatic eruptions.

Southern Andes↗