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Item type:Publication, Magnetotelluric images of the hydrothermal and magmatic system beneath Volcan Misti (Peru)(Elsevier BV, 2026-07-01)Volcan Misti, situated in the Central Volcanic Zone (CVZ) is considered one of the most hazardous volcanoes in South America. Petrophysical and mineralogical studies of the erupted materials inferred the presence of an interactive and stratified magmatic system, composed of two to three magma reservoirs. However, its geometry and the relationships with tectonic and seismic activity remain largely unresolved due to the lack of high-resolution geophysical imaging. To address this question, 42 broadband magnetotelluric (MT) stations were deployed around the volcanic edifice to construct the first three-dimensional electrical resistivity model of the magmatic and hydrothermal system. The data were inverted and the resulting model was characterized by three low-resistivity features. The first is a conductive layer, ∼1 km thick (5 to 40 Ωm), that extends laterally beneath the volcanic edifice and is interpreted as a clay cap. The second feature corresponds to an inferred low-resistivity body (10–30 Ωm), located at sea level. The third is a low-resistivity body (< 10 Ωm) imaged at ∼10 km below sea level, located slightly east of the volcano (∼2.5 km). The resistivity of this feature is interpreted as indicative of the presence of andesitic melts, suggesting a melt fraction in the range 4–24% for the temperature range 900–950 °C. The seismicity associated with the volcano is minimal and concentrated just beneath the crater at a depth of ∼2.5 km. The shallow depth of the seismicity, together with the MT model, suggests that the recharge and supply of magma occur in a cryptic manner. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Magma Storage Below Sabancaya Volcano (Southern Peru) Imaged by Broadband Magnetotellurics(Wiley, 2026-02-01)Sabancaya volcano is one of the most active volcanoes in the Central Andes. Its ongoing eruptive process is accompanied by large‐scale deformation, with activation of the Huambo‐Cabanaconde fault system, marked by intense seismicity over an area of about 50 × 30 . We present a pilot magnetotelluric survey performed in 2022, covering the Ampato‐Sabancaya complex, Hualca‐Hualca volcano, as well as the related system of normal faults. Our three‐dimensional electrical resistivity model reveals pronounced vertical gradients and lateral contrasts at elevations above sea level, along with generally low resistivity values at depth. Seismicity at depths km below sea level predominantly occurs in a low resistivity environment: 90% of seismic events occur at resistivity values below 10 m. Two prominent electrical conductors (<0.5 and 2–4 m) are imaged at depths 11–18 km and 3–8 km, respectively. Using petrological constraints, we interpret them as the signature of the magmatic plumbing system, connecting the Hualca‐Hualca and Ampato‐Sabancaya volcanoes. The deeper conductor is inferred to represent a magma reservoir situated beneath the older Hualca‐Hualca volcano, consistent with long‐term deformation and seismicity. It is connected to the laterally offset shallow magma chamber below Sabancaya. At depth 2–10 km, a strong conductor (<0.1 m) is imaged in the Huambo‐Cabanaconde fault zone. The extremely high conductivity of this body is attributed to the abundance of ultra‐saline brines, originating from the deep magma reservoir below. We speculate that the strong seismicity cluster detected in 2013 facilitated the passage of magmatic fluids exsolved from the magma reservoir, and replenished this ultra‐conductive body.2