Stacking of surface waves

Abstract

The seismic surface wave method (SWM) is a powerful means of characterizing near-surface structures. Although the SWM consists of only three steps (data acquisition, determination of dispersion curves, and inversion), it is important to take considerable care with the second step, determination of the dispersion curves. This step is usually completed by spectral analysis of surface waves (SASW) or multichannel analysis of surface waves (MASW). However, neither method is ideal, as each has its advantages and disadvantages. SASW provides higher horizontal resolution, but it is very sensitive to coherent noise and individual geophone coupling. MASW is a robust method able to separate different wave types, but its horizontal resolution is lower. Stacking of surface waves (SSW) is a good compromise between SASW and MASW. Using a reduced number of traces increases the horizontal resolution of MASW, and utilizing other shot records with the same receivers compensates for the decreased signal-to-noise ratio. The stacking is realized by summing the [Formula: see text] amplitude spectra of windowed shot records, where windowing produces higher horizontal resolution and stacking produces improved data quality. Mixing is applied between the stacks derived with different parameters, as different frequency ranges require different windowing. SSW was tested and corroborated on a deep seismic data set. Horizontal resolution is validated by [Formula: see text] plots at different frequencies, and [Formula: see text] plots present data quality.

Geophysical investigation of the Sandalp rock avalanche deposits

“…Several shots are considered for each position of the moving window and the dispersion curve is extracted from each shot. Stacking in the f-k domain is then applied to improve the S/N ratio (Neducza, 2007) and a new search is run on the stacked f-k gather. The dispersion curve that is then inverted is the one retrieved from the stacked data, while the ones obtained from single shot records are used to estimate the experimental uncertainties.…”

Application of Surface-Wave Methods for Seismic Site Characterization

“…7 New Perspectives: Interferometry and Tomography for Surveys in 2D/3D Sites Current trends in surface wave methods include attempts to evaluate lateral variations. Often this is pursued with a collection of adjacent surface wave surveys (Tian et al 2003;Bohlen et al 2004;Neducza 2007). Reinterpretation of seismic reflection/refraction datasets provides a cost effective approach in this respect (Grandjean and Bitri 2006;Socco et al 2009).…”

4. Advances in Surface-Wave and Body-Wave Integration

“…Considering seismic reflection data, several examples presented in literature have shown that surface-wave dispersion curves can be extracted conveniently from seismic reflection records (Park et al, 2005;Neducza, 2007). Because acquisition of reflection data usually is not optimized for surface waves, we first must assess whether the data fulfill the quality requirements for surface-wave analysis.…”