Abstract
It is essential to extract high-fidelity surface waves in surface-wave surveys. Because reflections usually interfere with surface waves on X components in multicomponent seismic exploration, it is difficult to extract dispersion curves of surface waves. To make matters worse, the frequencies and velocities of higher-mode surface waves are close to those of PS-waves. A method for surface-wave extraction is proposed based on the morphological differences between surface waves and reflections. Frequency-domain high-resolution linear Radon transform (LRT) and time-domain high-resolution hyperbolic Radon transform (HRT) are used to represent surface waves and reflections, respectively. Then, a sparse representation problem based on morphological component analysis (MCA) is built and optimally solved to obtain high-fidelity surface waves. An advantage of our method is its ability to extract surface waves when their frequencies and velocities are close to those of reflections. Furthermore, the results of synthetic and field examples confirm that the proposed method can attenuate the distortion of surface-wave dispersive energy caused by reflections, which contributes to extraction of accurate dispersion curves.
Highlights
Seismic surface waves are widely used in crustal and mantle structure studies as well as engineering prospecting
We propose a method of surface-wave extraction based on morphological component analysis (MCA) to avoid the overlaps between surface waves and reflections in the f-v domain
A comparison of Figures 4b and 5b demonstrates that reflections may disturb the dispersive energy of surface waves
Summary
Seismic surface waves are widely used in crustal and mantle structure studies as well as engineering prospecting. They are characterized by low attenuation with offset, a high signal-to-noise ratio, and dispersion [1,2]. Dispersion curves of fundamental-mode surface waves are inverted to obtain a near-surface S-wave velocity structure for PS-wave static corrections in seismic exploration [3,4]. Some studies have found that fundamental- and higher-mode surface waves have different sensitivities to elastic properties and thicknesses of near-surface materials [5,6]. To obtain accurate S-wave velocities, extraction of accurate dispersion curves of multi-mode surface waves is essential
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