Tracking three-dimensional growth of magma-filled fractures by joint inversion of high-resolution geodetic and seismicity data

Magma-filled fracture propagation is the primary magma transport mechanism near the surface at ocean island basaltic volcanoes. Therefore, developing and implementing efficient workflows to track magmatic intrusions in the elastic-part of the oceanic lithosphere (<10-20 km depth, usually corresponding to shallower than the Moho) is of great importance for volcano hazard assessment. Here, we implement a kinematic three-dimensional magma-filled fracture geomechanical model capable of jointly inverting observations of surface deformation and seismic data. We combine the strengths of both datasets: first by constraining the magma-filled fracture geometry using satellite radar interferometry and/or GPS, and second by kinematic magma migration using seismic data. The final output is a refined spatio-temporal evolution model of the magma propagation process, parametrized by fracture opening and shear stress changes. We apply this method to simulated cases and also to gain insights on the magma migration process occurring during real volcanic unrests in Canary Islands volcanoes. Our work aims to contribute knowledge that will help hazard assessment and volcanic risk reduction.Acknowledgements: We thank Spanish Agencia Estatal de Investigación projects PID2019-104571RA-I00 (COMPACT) funded by MCIN/AEI/10.13039/501100011033, and Project PID2022-139159NB-I00 (Volca-Motion) funded by MCIN/AEI/10.13039/501100011033 and “FEDER Una manera de hacer Europa”. Research activities of the CSIC staff during the 2021 La Palma eruption were funded by CSIC -CSIC-PIE project PIE20223PAL008. This work was also partially supported by project PTDC/CTA-GEO/2083/2021 GEMMA, funded by Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES. We thank INTA La Palma Announcement of Opportunity and Hisdesat for providing timely PAZ satellite radar data and also the Italian Space Agency (ASI) for providing Cosmo-SkyMed data within the CEOS Volcano Demonstrator.