Frequency‐dependent multi‐offset phase analysis of surface waves: an example of high‐resolution characterization of a riparian aquifer. (6th May 2015)

• Record Type: Journal Article
• Authors: Vignoli, Giulio; Gervasio, Isabella; Brancatelli, Giuseppe; Boaga, Jacopo; Della Vedova, Bruno; Cassiani, Giorgio
• Is Part Of: Geophysical prospecting. Volume 64:Number 1(2016)
• Page Start: 102
• Page End: 111
• Publication Date: 2015-05-06
• Subjects: Multi‐offset phase analysis -- Rayleigh wave -- surface wave -- refraction seismics -- Electrical resistivity tomography; Prospecting -- Geophysical methods -- Periodicals; 622.15
• DOI: 10.1111/1365-2478.12256
• Languages: English
• ISSNs: 0016-8025

Abstract

ABSTRACT: Multi‐offset phase analysis of seismic surface waves is an established technique for the extraction of dispersion curves with high spatial resolution and, consequently, for the investigation of the subsurface in terms of shear wave velocity distribution. However, field applications are rarely documented in the published literature. In this paper, we discuss an implementation of the multi‐offset phase analysis consisting of the estimation of the Rayleigh wave velocity by means of a moving window with a frequency‐dependent length. This allows maximizing the lateral resolution at high frequencies while warranting stability at the lower frequencies. In this way, we can retrieve the shallow lateral variability with high accuracy and, at the same time, obtain a robust surface‐wave velocity measurement at depth. In this paper, we apply this methodology to a dataset collected for hydrogeophysical purposes and compare the inversion results with those obtained by using refraction seismics and electrical resistivity tomography. The surface‐wave results are in good agreement with those provided by the other methods and demonstrate a superior capability in retrieving both lateral and vertical velocity variations, including inversions. Our results are further corroborated by the lithological information from a borehole drilled on the acquisition line. The availability of multi‐offset phase analysis data also allows disentangling a fairly complex interpretation of the other geophysical results.