Applying the Spanish Inventory of Sites of Geological Interest (IELIG) to the 2021 Tajogaite Eruption: Insights and Lessons Learned

On September 19^th, 2021, the last eruption from the Canarian archipelago began on La Palma island. The youngest Spanish volcano, called Tajogaite, produced one of the most complex and extensive lava field ever documented in the Canary Islands. The eruption was a multi-vent fissural eruption with effusive and explosive volcanic activity. With a mean discharge rate of 32.7m³s^-1, the Tajogaite volcano emitted 242m³ of volcanic material (Calvari et al., 2026) and covered 1.219e+7m² of surface with lava flows. The socioeconomic impact resulted in 3.7e+6m² of cropped area, 3126 edifices, including 75 industrial facilities, 5445 parcels, and 92 km of roads destroyed (Copernicus EMS. https://emergency.copernicus.eu/; BOPC núm.533,14/12/2022). After the eruption, recovery and rehabilitation of the affected areas became challenging, being mainly focused on demolition and clearing land projects. However, this eruption has highlighted the scientific challenge of determining the most valuable volcanic features for protection (Vegas et al., 2022). To ensure a sustainable development of land recovery, the Geological and Mining Institute of Spain (IGME-CSIC) made a fast-response report to the regional authorities with an integral geoheritage assessment and mapping of the most valuable volcanic elements that should be included in the new regional legislation, including precautionary measures for conservation of the best geoheritage elements of this volcano.

Geoheritage mapping was carried out in 2022 through the integration of high-resolution satellite imagery, drone-based photogrammetry, and fieldwork observations. The resulting products included: (1) initial request for the expansion of the Natural Protected Areas of Cumbre Vieja, consisting in one map with three areas of ∼311ha with high scientific value, 10 maps with the scientific, touristic and fragility values and 34 types of Elements of Volcanic Interest (EVI), representing the first approach of a detailed official quantitative value of Tajogaite volcano; (2) A new geoheritage methodology developed for the Tajogaite eruption in accordance with the IELIG and the Spanish Law.42/2007 “on the natural heritage and biodiversity”.

The EVIs were identified based on morphological, textural, lava flow margins and lava tube-related structures. A special case of this eruption is the network of lava tubes that played a unique role transporting lava flows over long distances (Sanz-Mangas et al., 2025), allowing sustained advance to the coast. Due to their unique features, these EVIs have a high potential for research and geotourism. While post-eruption reconstruction is essential for the recovery and well-being of the affected communities, the irreversible destruction of many of the most valuable EVI, still not declared protected natural areas by the Canary Islands Government, has led to the loss of a unique volcanic landscape, hindering scientific progress and limiting future opportunities for society to benefit from this geoheritage.

Calvari et al. (2026). Bulletin of Volcanology, 88,8. https://doi.org/10.1007/s00445-025-01925-x

Sanz-Mangas et al. (2022). Cosmológica, ISSN 2792-7423, p113-115

Vegas et al. (2022). Official Report “Propuesta de Protección de los Elementos de Interés Geológico para el Territorio Afectado por la Erupción de 2021”. Unpublished.

Acknowledgements

This project was developed under the Sub-Project 1 ‘Canary Islands, destiny of Volcanoes’ funded by PROMOTUR Turismo Canarias,S.A. through Next Generation EU-funds, PRTR. 2024krQ00nnn; and MITECO (227G0165-GEOPALMA).