Measuring the scattering mean free path of Rayleigh waves on a volcano from spatial phase decoherence

Anne Obermann (1) , Éric Larose (1) , Ludovic Margerin (2) , Vincent Rossetto (3)

1 ISTerre - Institut des Sciences de la Terre
2 IRAP - Institut de recherche en astrophysique et planétologie
3 LPM2C - Laboratoire de physique et modélisation des milieux condensés

We analyse the statistics of phase fluctuations of seismic signals obtained from a temporary small aperture array deployed on a volcano in the French Auvergne. We demonstrate that the phase field satisfies Circular Gaussian statistics. We then determine the scattering mean free path of Rayleigh waves from the spatial phase decoherence. This phenomenon, observed for diffuse wavefields, is found to yield a good approximation of the scattering mean free path. Contrary to the amplitude, spatial phase decoherence is free from absorption effects and provides direct access to the scattering mean free path.

Mots clés: Surface waves and free oscillations; Coda waves; Statistical Seismology; Wave scattering and diffraction

Domaines: Géophysique [physics.geo-ph]; Acoustique [physics.class-ph]; Analyse de données, Statistiques et Probabilités [physics.data-an]

Anne Obermann, Éric Larose, Ludovic Margerin, Vincent Rossetto. Measuring the scattering mean free path of Rayleigh waves on a volcano from spatial phase decoherence. Geophysical Journal International, 2014, 197 (1), pp.435. ⟨10.1093/gji/ggt514⟩. ⟨hal-01075270⟩