Details of the Abstract
| Title of paper | Magma reservoir below Sabancaya volcano (Southern Peru) imaged by broadband magnetotellurics |
| List of authors | Torres, J., Byrdina, S., Garambois, S., Antayhua, Y., Romero, G., Rath V., Tavera, H., Milla, M. |
| Affiliation(s) |
(Torres, J., Milla, M. ): Pontificia Universidad Católica del Perú, Av. Universitaria s/n, San Miguel, Lima, Perú. (Byrdina, S., Garambois, S.): Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre, 38000 Grenoble, France. (Antayhua, Y., Romero, G., Tavera, H.): Instituto Geofísico del Perú, Observatorio Vulcanológico del Sur, Asentamiento Humano José María Arguedas Zona A Mz. D Lt. 08, Sachaca, Arequipa, Perú. (Rath V.) Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin, Ireland. |
| Summary | Here, we present a 3D electrical resistivity map inverted from MT measurements acquired using broadband Metronix instruments on 33 sites in November 2022. We compare the resistivity map to results from seismological and geodetic studies. The resistivity map exhibits high contrast resistivity regions and several extended conductive bodies. We analyze these structures based on their depths and lateral locations relative to the volcanic edifices and fault systems. Below the shallow hydrothermal system, two interconnected conductors (<0.5 Ωm) are imaged: between ~12.5 and 18 km and ~2 and 8 km below the surface, in areas characterized by long-term deformation and intense seismicity. We interpret both conductors as a magmatic reservoir feeding the Hualca-Hualca and Ampato-Sabancaya volcanoes. Above the western branch of this reservoir, in the Huambo-Cabanaconde fault zone, a highly conductive body (<0.2 Ωm) is imaged between 2 and 7 km below the surface. Because of the extremely low resistivity of this body, we interpret it as ultra-saline brines originating from the magmatic reservoir and emplaced (or replenished) during the unrest episode in 2013. Another conductor is found East of the Ampato volcano in an aseismic area with no surface hydrothermal manifestations. We associate this body with a fossil hydrothermal system remaining from past eruptions. In our interpretation, the injection of magmatic fluids from the deep magmatic chamber to the shallow zone causes the deformation observed in the volcanic zone since 2013 and also activation of fault systems and the subsequent occurrence of intense seismic activity in the Colca valley. |
| Session Keyword | 4.0 Tectonics and geodynamics, including magmatism |
| File upload |
4.0_magma_reservoir_below_sab_torres_aguilar_02.pdf
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