Asymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveys

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dc.contributor.authorGonzales, Katherine
dc.contributor.authorFinizola, Anthony
dc.contributor.authorLénat, Jean-François
dc.contributor.authorMacedo Sánchez, Orlando Efraín
dc.contributor.authorRamos Palomino, Domingo A.
dc.contributor.authorThouret, Jean-Claude
dc.contributor.authorFournier, Michel
dc.contributor.authorCruz, Vicentina
dc.contributor.authorPistre, Karine
dc.coverage.spatialUbinas, Volcán (Moquegua, Perú)
dc.date.accessioned2018-09-11T19:54:08Z
dc.date.available2018-09-11T19:54:08Z
dc.date.issued2014-04
dc.description.abstractUbinas volcano, the historically most active volcano in Peru straddles a low-relief high plateau and the flank of a steep valley. A multidisciplinary geophysical study has been performed to investigate the internal structure and the fluids flow within the edifice. We conducted 10 self-potential (SP) radial (from summit to base) profiles, 15 audio magnetotelluric (AMT) soundings on the west flank and a detailed survey of SP and soil temperature measurements on the summit caldera floor. The typical “V” shape of the SP radial profiles has been interpreted as the result of a hydrothermal zone superimposed on a hydrogeological zone in the upper parts of the edifice, and depicts a sub-circular SP positive anomaly, about 6 km in diameter. The latter is centred on the summit, and is characterised by a larger extension on the western flank located on the low-relief high plateau. The AMT resistivity model shows the presence of a conductive body beneath the summit at a depth comparable to that of the bottom of the inner south crater in the present-day caldera, where intense hydrothermal manifestations occur. The lack of SP and temperature anomalies on the present caldera floor suggests a self-sealed hydrothermal system, where the inner south crater acts as a pressure release valve. Although no resistivity data exists on the eastern flank, we presume, based on the asymmetry of the basement topography, and the amplitude of SP anomalies on the east flank, which are approximately five fold that on the west flank, that gravitational flow of hydrothermal fluids may occur towards the deep valley of Ubinas. This hypothesis, supported by the presence of hot springs and faults on the eastern foot of the edifice, reinforces the idea that a large part of the southeast flank of the Ubinas volcano may be altered by hydrothermal activity and will tend to be less stable. One of the major findings that stems from this study is that the slope of the basement on which a volcano has grown plays a major role in the geometry of the hydrothermal systems. Another case of asymmetrical composite cone edifice, built on a steep topography, is observed on El Misti volcano (situated 70 km west of Ubinas), which exhibits a similar SP pattern. These types of edifices have a high potential of spreading and sliding along the slope owing to the thicker accumulation of low cohesion and hydrothermally altered volcanic products.es_ES
dc.description.peer-reviewPor pareses_ES
dc.formatapplication/pdfes_ES
dc.identifier.citationGonzales, K., Finizola, A., Lénat, J. F., Macedo, O., Ramos, D., Thouret, J. C., ... Pistre, K. (2014). Asymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveys.==$Journal of Volcanology and Geothermal Research, 276,$==132-144. https://doi.org/10.1016/j.jvolgeores.2014.02.020es_ES
dc.identifier.doihttps://doi.org/10.1016/j.jvolgeores.2014.02.020es_ES
dc.identifier.govdocindex-oti2018
dc.identifier.journalJournal of Volcanology and Geothermal Researches_ES
dc.identifier.urihttp://hdl.handle.net/20.500.12816/2924
dc.language.isoenges_ES
dc.publisherElsevieres_ES
dc.relation.ispartofurn:issn:0377-0273
dc.rightsinfo:eu-repo/semantics/closedAccesses_ES
dc.subjectUbinas volcanoes_ES
dc.subjectHydrothermal systemes_ES
dc.subjectSelf-potentiales_ES
dc.subjectAudio-magnetotelluric soundingses_ES
dc.subjectSoil temperaturees_ES
dc.subjectEdifice stabilityes_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.00es_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.04es_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.06es_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.07es_ES
dc.titleAsymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas volcano, Peru, revealed by geophysical surveyses_ES
dc.typeinfo:eu-repo/semantics/articlees_ES

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