P and PS data to reduce the uncertainty in the reconstruction of near-surface alluvial deposits (Case study—Central Italy)

• Published in: Journal of applied geophysics 2010-09, Vol.72 (1), p.57-69
• Main Authors: Orlando, Luciana, Pelliccioni, Giovanni
• Format: Article
• Language: English
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Electrical resistivity data; Exact sciences and technology; Internal geophysics; Joint data interpretation; Multi-array surficial waves; P and PS waves; Seismic reflection; Seismic refraction
• ISSN: 0926-9851; 1879-1859
• DOI: 10.1016/j.jappgeo.2010.07.002

Seismic refraction, surface wave surveys and P and PS seismic reflection data were acquired and processed to derive the geological setting as well as P and S velocity profiles of the Plio–Pleistocene sediments that are filling a tectonic valley in central Italy. The results were constrained by boreholes, vertical electrical sounding and electrical resistivity tomography. The P-wave data, processed with standard processing, was allowed to detect the top of limestone 50 m depth. The converted PS-wave data were processed with Asymptotic Common Conversion Point (ACCP) sort and non-hyperbolic normal move out correction. The study shows that special care must be devoted to data muting because of the low signal-to-noise ratio, which is mainly due to the high energy of the ground roll and the air wave. The stack section was the result of an iterative process. From theoretical analysis, we determined that the use of ACCP binning does not allow the reflection to be focused for all of the time windows because the ACCP approximation is correct only for depths greater than the shot-receiver offset. The joint interpretation of the direct and indirect data proved the capability of P and PS seismic reflection data of constraining the interpretation and removing the ambiguity in the reconstruction of the geological setting and the P and S profiles of the formation of an alluvial valley located in a seismic area. ►Joint interpretation of direct and indirect surveys to constrain interpretation for near surface formations. ►Refraction, compressional, converted and surface waves to perform P and S near surface seismic profiles. ►Asymptotic common conversion point focuses only the reflection responding to the actual Vs-Vp ratio.