ALBERT

Description: Identifying the observables that warn of volcanic unrest and eruptions is one of the greatest challenges in natural hazard management. Recently, Girona et al., 2021 (https://www.nature.com/articles/s41561-021-00705-4), discovered that volcanic edifices may slightly warm in the years leading up to both phreatic and magmatic eruptions. This warming, or low-temperature (low-T) geothermal anomaly, was found by analyzing ~16 years of long-wavelength (~11 μm) thermal infrared radiance data recorded by the moderate-resolution imaging spectroradiometers (MODIS) aboard NASA's Terra and Aqua satellites. However, many questions remain open. For example: What is the link between the spatiotemporal distribution of low-T geothermal anomalies and subsurface gas transport? We address this question by updating the remote sensing-based methodology proposed by Girona et al. (2021), by testing different physics-based, finite element (COMSOL) simulations to model gas and heat transport through volcanic edifices, and by using the 2021 Cumbre Vieja (La Palma, Spain) eruption as a case study. Our remote sensing-based analysis reveals that the 2021 Cumbre Vieja eruption was preceded by ~10 years of low-T geothermal anomalies in the crater of Taburiente caldera, located 10-to-12 km to the north of the 2021 eruptive center. Moreover, our models suggest that the pre-eruptive, low-T geothermal anomalies were possibly controlled by the latent heat released during the subsurface condensation of magmatic and/or hydrothermal H〈sub〉2〈/sub〉O. The possibility of tracking the spatiotemporal distribution of low-T geothermal anomalies using satellite data opens new horizons to indirectly detect the pre-eruptive transport of hot gas towards the surface and potentially better forecast eruptions from space.