Tomography of the Alps using seismic ambient noise

We use seismic ambient noise correlation to study the lithosphere in western Europe. Cross correlation of one year of noise recorded at 150 3-components broadband stations yields more than 3000 Rayleigh and Love wave group velocity measurements. These measurements are used to construct Rayleigh and Love group velocity models of the Alpine region and surrounding area in the 5-50s period band. The seismic noise recorded in Europe is dominated by noise originating from the Northern Atlantic ocean. This anisotropy of the noise and the uneven station distribution affect the azimuthal distribution of the paths where we obtain reliable group velocity measurements. As a consequence our group velocity models have better resolution in the South-East direction than in the North-West direction. Finally we invert the resulting Rayleigh wave group velocity maps to determine the Moho depth. Our results are in good agreement with the result of the numerous active experiments in the Alps.