Tomography of the Alpine region from observations of seismic ambient noise

L. Stehly (1, 2) , B. Fry (3) , Michel Campillo (1) , N.M. Shapiro (4) , J. Guilbert (2) , L. Boschi (3) , D. Giardini (3)

1 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
2 DAM/DIF - DAM Île-de-France
3 ETH Hoenggerberg
4 IPGP - Institut de Physique du Globe de Paris

We use correlations of the ambient seismic noise to study the crust in western Europe. Cross correlation of 1 year of noise recorded at 150 three components broadband stations yields more than 3 000 Rayleigh wave group velocity measurements. These measurements are used to construct Rayleigh group velocity maps of the Alpine region and surrounding area in the 5–80 s period band. In the 5–10 s period band, the seismic noise recorded in Europe is dominated by surface waves 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 northeast direction than in the southwest 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 and provide a continuous image of the Alpine structure.

Mots clés: Tomography; Surface waves and free oscillations; Seismic tomography; Europe

Domaines: Planète et Univers [physics]

L. Stehly, B. Fry, Michel Campillo, N.M. Shapiro, J. Guilbert, et al.. Tomography of the Alpine region from observations of seismic ambient noise. Geophysical Journal International, 2009, 178 (1), pp.338-350. ⟨10.1111/j.1365-246X.2009.04132.x⟩. ⟨insu-00447974⟩