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The Domuyo volcanic complex (DVC) and its geothermal field in the retroarc zone of the southern Central Andes of Argentina present reduced seismicity according to different catalogs (USGS and INPRES). However, in 2015/2016, a local project was carried out in the area to describe its seismo-volcanic activity, registering a large number of volcano-tectonic (VT) events (538 VT). Considering there is scarce information on these events, this study focuses on analyzing the Domuyo Volcanic Complex (DVC) to assess its seismicity. Therefore, we installed a local seismological network in the study area and compared results with data registered by other authors. Four seismological networks were used, to obtain a more precise location of the seismic events and calculate the focal mechanisms of earthquakes with magnitudes greater than 2. For the first record of crustal seismicity detected by INPRES the September 10th, 2016 with a Ml 3.3, we calculated the focal mechanism with two possible solutions: a thrust solution with a strike component and a favored normal solution with a strike component. Additionally, we relocated the largest event in the Domuyo region on March 27th, 2019, with a magnitude of 4.4 (NEIC – USGS) and focal mechanism with a normal solution and a small strike component, obtaining a shallower depth of 3.9 km instead of 10 km. The new seismological data used in this paper, correspond to September 10th 2016, and two different time periods, the first comprising continuous data from March to April 2019, when the largest registered earthquake occurred in the Domuyo region, and the second from December 2019 to January 2021. At these periods, registered seismicity had magnitudes Ml between 1.9 and 2.8, and focal depths between 1.8 and 5.2 km. Four of these events count with focal mechanisms with extensional and limited strike-slip components that are tentatively linked to the known neotectonic structures affecting the western slope of the DVC. This seismic sequence agrees with previous proposals in which degasification from a magmatic body at shallow depths constitutes the trigger factor. • First focal mechanisms in Domuyo Volcanic Complex (DVC), with principally normal solution. • DVC from 2016 to 2020 was subject to an extensional deformation. • This deformation is associated with the degasification of a shallow magmatic body. [ABSTRACT FROM AUTHOR]

This paper discusses the challenges and opportunities for cross-border eruption management between Chile and Argentina, focussing on an examination of the 2011–2012 eruption of Cordon Caulle in Chile and other crises between 2012 and 2015. We discuss the differences between Chile and Argentina in volcano monitoring, eruption impacts, eruption management and governance during this timeframe. We also discuss the issues in communication of the risks and the potential for future integration at the scientific level. The study is based on 31 interviews with scientists and local officials in 2014–15 (15 in Chile and 16 in Argentina), a questionnaire survey of 128 Argentinian residents in 2015 and a questionnaire survey of 25 disaster managers and residents of Pucón during the 2015 eruption of Villarrica volcano. We conclude that in 2011–12, there were issues with communication across the border, particularly at the political level, and that there are important ways that the scientific institutions in both countries complement each other. • We present new social data concerning the 2011–12 eruption of Puyehue Cordon Caulle. • We show that the eruption was significant in the evolution of institutions and agreements between the countries. • We show that locally, there was dissatisfaction with risk communication in Argentina (which was worse affected). • We argue that the scientific institutions complement each other well but need more resourcing from government. [ABSTRACT FROM AUTHOR]

The western slope of Cerro Domuyo in northern Patagonia is characterized by thermal springs with boiling waters, Quaternary silicic domes, and pyroclastic deposits that suggest the existence of a geothermal reservoir. According to geochemical studies, the reservoir may have a temperature of 220 °C and one of the largest advective heat fluxes reported for a continental volcanic center. In this paper, we propose a more refined conceptual model for the Domuyo geothermal area, based on a geological survey supported by U Pb, U Th, and Ar Ar geochronology and by magnetotelluric and gravity surveys. Our study indicates that the Domuyo Volcanic Complex (DVC) is a Middle Pleistocene dome complex overlying middle Miocene to Pliocene volcanic sequences, which in turn cover: 1) the Jurassic-Early Cretaceous Neuquén marine sedimentary succession, 2) silicic ignimbrites dated at ~186.7 Ma, and 3) the Paleozoic metamorphic basement intruded by ~288 Ma granite bodies. The volcanic cycle in the DVC is distinctly bimodal, characterized by the emplacement of massive silicic domes and less voluminous olivine basalts on its southern slope. A major collapse of the central dome at ~600 ka produced a voluminous (19.4 km3 and 133 km2) block-and-ash flow, and associated pyroclastic flows, that filled a valley to the southwest at distances up to ~30 km from Cerro Domuyo summit. This was followed by a period of intense effusive activity that formed the Cerro Guitarra, Cerro Las Pampas, Cerro Domo, and Cerro Covunco silicic domes. The last two domes are the youngest and largest edifices, dated at 0.50 Ma (Ar Ar age) and 0.25 Ma (U Th age). Pre-Cenozoic successions were affected by N-S reverse and thrust faults that were later displaced by an ENE-WSW-trending transtensional belt. The basement rocks at the northern termination of the Cordillera del Viento anticlinorium were also displaced towards the east-northeast by this belt, which is observed NNW of Cerro Domuyo. The DVC was emplaced within this zone of crustal weakness. The integration of geologic observations with magnetotelluric and gravity data, allowed us to develop an updated conceptual model of the geothermal system. The geothermal reservoir is inferred at a depth of less than 2 km within pre-Pliocene fractured rocks, bounded by ~WSW-ENE trending faults and sealed by the pyroclastic deposits and rhyolitic lavas of the DVC. The location of most thermal springs is not directly controlled by faults. Instead, flows emerge at the contact between the fractured and faulted basement and the caprock. • The Domuyo Volcanic Complex (DVC) is a silicic dome complex formed in the Pleistocene. • The central dome collapsed at ~600 ka producing a voluminous (19.4 km3) pyroclastic deposit. • The youngest domes were emplaced at ~500 ka and 250 ka. • The DVC was emplaced within a ENE-WSW trending transtensional zone of crustal weakness. • The geothermal reservoir is hosted in pre-Pliocene rocks sealed by the DVC pyroclastics and lavas. [ABSTRACT FROM AUTHOR]