ALBERT

Description: The receiver function analysis (RF) is a well-established method to investigate the crustal and upper mantle structure in different geodynamic settings. It is highly sensitive to seismic discontinuities and provides information about P- and S-wave velocities beneath a seismic station. This work aims to study the crust and the upper mantle of La Palma Island up to 50 km of depth by using RF analysis. La Palma is one of the youngest oceanic volcanic islands of the Canary archipelago, with a complex internal structure that makes applying conventional RF challenging. The island was affected in 2021 by the devastating Tajogaite eruption which occurred on the Cumbre Vieja volcano. For this study, we obtained RFs of five stations using multi-taper deconvolution. After that, we applied the transdimensional approach of Bodin et al. (2012) to determine 1D profiles of P- and S-wave velocities and the probability of a discontinuity beneath each station. Each 1D model was interpolated to build a N-S trending seismic section that allowed us to correlate the different discontinuities. We observe a Low-Velocity Zone in the upper mantle beneath the Cumbre Vieja volcano and four different layers with a significant change in their Vp/Vs ratios. These results are compared with the seismicity recorded beneath the island from 2017 until the pre-eruptive phase of the Tajogaite eruption. Hypocenters are mainly located at the base of the crust (10-15 km deep) and in the upper mantle (20-30 km deep), possibly related to the presence of two subcrustal magmatic reservoirs.