La Palma island (Spain) geothermal system revealed by 3D magnetotelluric data inversion

Abstract

The study of geothermal systems is nowadays a topic of great importance because of the huge amount of energy that could be converted in electricity for human consumption from such sources. Among the various geophysical methods employed to study geothermal reservoirs, the magnetotelluric (MT) method is capable to reveal the internal structures of the subsurface and interpret the geological structures from the electrical resistivity. We present the first 3D resistivity model of La Palma (Canary archipelago, Spain) obtained from a dataset of 44 broadband magnetotelluric soundings distributed around the island. Our results highlight the presence of resistivity anomalies, spatially coinciding with density anomalies present in literature. In the north of the island, a high resistivity anomaly can be interpreted as the signature of an old intrusive body beneath the Taburiente caldera. In the south, a complex resistivity structure around the Cumbre Vieja volcanic ridge could be indicative of presence of an active geothermal system. In particular, low-resistivity anomalies, located in a high-fractured zone, have values compatible with clay alteration caps (illite and illite–smectite). Such a result suggests the presence of hot rocks, or a dike system, heating fluids in the interior of Cumbre Vieja volcanic system.

Early Precursory Changes in the 3He/4He Ratio Prior to the 2021 Tajogaite Eruption at Cumbre Vieja Volcano, La Palma, Canary Islands

“…(2022), with good spatial correspondence with a low‐resistivity anomaly measured through a magnetotelluric survey by Di Paolo et al. (2020) after seismic swarms of 2017 and February 2018, represent clear evidences of the magma pockets' rise that took place in 2017–2018 beneath Cumbre Vieja volcano.…”

Voluminous Storage and Rapid Magma Ascent Beneath La Palma Revealed by Seismic Tomography

“…(2) Underlying the volcanically active sector of La Palma is a spatially limited high Vp/Vs (> 2) and low velocity (Vp and Vs > 10% below the average) structure extending from the surface to ~3 km bsl. This structure has previously been identi ed as a high-resistivity hydrothermal zone 11 .…”

Estimation of Spatial Distribution and Fluid Fraction of a Potential Supercritical Geothermal Reservoir by Magnetotelluric Data: A Case Study From Yuzawa Geothermal Field, NE Japan

“…The MT method is a geophysical tool used to map the electrical resistivity structure of subsurfaces (Araya Vargas et al., 2019; Árnason et al., 2010; Becken et al., 2011; Bedrosian et al., 2018; Di Paolo et al., 2020; Heinson et al., 2018; Heise et al., 2008; Hyndman & Shearer, 1989; Ichihara et al., 2016; Ingham et al., 2009; Le Pape et al., 2015; Moorkamp et al., 2019; Wise & Thiel, 2020). This method uses surface measurements of naturally occurring low‐frequency electromagnetic variations to investigate underground resistivity structures (Chave & Jones, 2012).…”