Rayleigh wave attenuation and phase velocity maps of the greater Alpine region from ambient noise

We use seismic ambient noise data from 724 publicly available broadband seismic stations across central Europe to create detailed phase velocity and attenuation maps of Rayleigh waves, focusing on short periods down to 3 s. We interpret these maps in terms of the underlying physical processes relevant to the nature of continental crust. Through a regionalized interpretation based on tectonic settings, we highlight the significant role of fluid-filled fractures in the attenuation of surface waves. Our findings indicate a close connection between the time elapsed since the last tectonic activity in the European crust and the attenuation coefficient values. Additionally, we observe a pronounced decrease in attenuation coefficient values at periods below 6 s. The anti-correlation between attenuation coefficient and phase velocity in recently active tectonic regions suggests that fluid-filled fractures are likely the dominant factor governing seismic attenuation in the European crust.