Regional Crustal Imaging by Inversion of Multimode Rayleigh Wave Dispersion Curves Measured From Seismic Noise: Application to the Basque-Cantabrian Zone (N Spain)

Abstract

Seismic-noise tomography is routinely applied for imaging geological structures at different spatial scales. The frequently used time-domain approach presents two limitations. First, extracting surface-wave group velocities from time-domain cross-correlations requires interstation distances of at least three wavelengths, which may be problematic when working at local or regional scales. Second, the presence of higher modes of surface waves in the cross-correlation functions is often disregarded, which may cause loss of valuable information about the shear-wave velocity structure. In this work, we present a complete inversion scheme that avoids these limitations and use it to obtain a 3D shear-wave velocity model of the Basque-Cantabrian Zone (N Spain), a structurally complex area affected by multiple tectonic events. The resulting model agrees with the existing geological and geophysical knowledge and significantly extends the area for which high-resolution information is available.