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The Cerro Overo volcano is a monogenetic center of the Holocene age located in the north of Chile in the Central Volcanic Zone of the Andes, which is part of the Altiplano-Puna Volcanic Complex. Based on petrological and geochemical data, it has been classified by Ureta et al. (2021) as a phreatomagmatic explosion crater generating a maar-type structure with a diameter of 600 m. Our interest lies in the morphological difference between Cerro Overo with the nearby eruptive centers. Its current morphology is inferred from a phreatomagmatic eruption during its magma ascent. The initial hypothesis is that the electrical resistivity model would allow the identification of fluids and typical structures of magma-water explosions. Broadband magnetotelluric (MT) soundings were carried out in the surroundings of the volcano, managing to identify the distribution of low-resistivity structures up to the first kilometers, becoming more resistive with depth. This structure would correspond to the diatreme as a remnant of the eruption percolated by fluids in its upper part., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)