Gravimetric and magnetic 3D joint modelling of La Palma, Canary Islands, for geothermal resources exploration.

The energy supply of the Canary Islands currently depends on more than 95% of fossil fuel sources, with geothermal research constituting a strategic action. Geophysical monitoring is essential to understand subsurface processes and properties to significantly enhance the potential of geothermal energy development in La Palma. In the 90s and early 2000s, several geophysical surveys were conducted in the island, but data for each physical property were modelled separately. However, regional anomalies such as gravimetric and magnetic offer complementary information about target structures and therefore, can be advantageously modelled together to obtain more constrained and thus more reliable models. An intuitive and easily comprehensive 3D model is conceived to study La Palma thermal lithosphere. Magnetic anomaly data are retrieved from the aeromagnetic flight carried out by the Instituto Geográfico Nacional (IGN) in 1993 (Socías & Mezcua, 1996). Bouguer anomaly data for this study are composed of those observed in 2005 and 2021, published in Montesino et al. (2023), and those acquired by the IGN levelling network in early 2000s. We processed the data using ZondGM3D modelling software. As a part of our results, we aim to compare the 3D density and magnetization distribution models of La Palma after individual and joint data inversions. In addition, we will discuss and compare our results with Di Paolo et al. (2020) geothermal system revealed using magnetotellurics and the electrical resistivity model from Piña-Varas et al. (2023) volcanic monitoring, including other previous gravity and magnetic anomaly models from literature. This study is part of the GEOTHERPAL project in which several Spanish institutions aim to perform a multidisciplinary and multiscale geophysical and geochemical imaging of La Palma Island geothermal system, essential to estimate its energy potential. More details are found at the web site of the project: http://pc213fis.fis.ucm.es/GEOTHERPAL/index.html