3-D Intrinsic Attenuation Tomography of La Palma island (Canary Islands) using Ambient Seismic Noise

Seismic attenuation plays a vital role in geothermal exploration due to its direct association with the fluid content of reservoirs. In this study, we obtained the first attenuation model of La Palma island (Canary Islands) for geothermal exploration, applying a novel local-scale ambient noise attenuation tomography technique. Data from 44 seismic stations underwent meticulous processing. The initial stages involved preprocessing ambient noise data via standard normalization techniques, bandpass filtering and cross-correlation to retrieve the Empirical Green's functions (EGFs). For each EGF we retrieve the intrinsic attenuation  across various frequencies using the lapse-time dependence method, in which intrinsic attenuation is measured as a function of the coda window length for different onsets of the ambient-noise cross-correlation coda (Calvet and Margerin, 2013). Subsequently, 2-D spatial intrinsic attenuation maps for different frequencies were generated through linear inversion using sensitivity kernels (Del Pezzo and Ibáñez, 2020). Finally, we inverted the 2-D spatial intrinsic attenuation maps to derive 1-D depth profiles of intrinsic attenuation. The results unveiled distinct high-attenuation anomalies which releveled a possible hydrothermal zone  beneath the southern part of La Palma island. Comparative analyses with previous resistivity studies (Di Paolo et al., 2020), S-wave velocity research (Cabrera-Pérez et al., 2023), and density models (Montesinos et al., 2023) further corroborated these findings, underscoring the significance of ambient noise attenuation tomography in geothermal exploration. References: Cabrera-Pérez, I. et al. Geothermal and structural features of La Palma island (Canary Islands) imaged by ambient noise tomography. Sci. Reports 13, 12892 (2023) Calvet, M. & Margerin, L. Lapse-time dependence of coda q: Anisotropic multiple scattering models and application to the pyrenees. Bull. Seismol. Soc. Am. 103, 1993–2010 (2013). Del Pezzo, E. & Ibáñez, J. M. Seismic coda-waves imaging based on sensitivity kernels calculated using an heuristic approach. Geosciences 10, 304 (2020). Di Paolo, F. et al. La Palma island (Spain) geothermal system revealed by 3D magnetotelluric data inversion. Sci. reports 10, 1–8, DOI: 10.1038/s41598-020-75001-z (2020). Montesinos, F. G. et al. Insights into the magmatic feeding system of the 2021 eruption at Cumbre Vieja (La Palma, Canary Islands) inferred from gravity data modeling. Remote. Sens. 15, 1936 (2023)