Crustal structure deduced from receiver functions via single-scattering migration

E. Bertrand , Anne Deschamps (1) , J. Virieux (1)

1 GEOAZUR 6526 - Géoazur

An investigation of the teleseismic P-wave coda is performed using the single-scattering approximation. The method allows one to image short-wavelength scale (≤2 km) velocity and density heterogeneities and structures that are barely detected by traveltime tomography. Source effects are removed by using receiver functions for data interpretation, but the amplitude (especially the sign of the signal) is synthesized. Both broad-band seismological stations in the southwestern Alps (France) and Campanian plain (Italy) are used for the illustration of the proposed method. Because of the large aperture of our arrays, laterally small-scale heterogeneities are difficult to image and we must assume lateral continuity of the detectable structure. If so, we show that this depth migration based on a single-scattering approach can recover both the depth and the geometry of the main discontinuities below the studied areas. In the southwestern Alps, we underline a complex crustal structure and Moho dipping topography. The Moho depth increases from 20 to 30 km between the coastline and the Mercantour range. In the Campanian plain (surrounding Mount Vesuvius) we also find a southeastwards-dipping Moho. Furthermore, the three main discontinuities are imaged, showing a relatively shallow mantle-crust discontinuity and a deeper one near the coastline.

Mots clés: body waves; broad-band; crustal structure; Moho discontinuity; P-to-S conversions; scattering; waveform analysis

Domaines: Planète et Univers [physics]

E. Bertrand, Anne Deschamps, J. Virieux. Crustal structure deduced from receiver functions via single-scattering migration. Geophysical Journal International, 2002, 150 (2), pp.524-541 [416]. ⟨10.1046/j.1365-246X.2002.01723.x⟩. ⟨hal-00406659⟩