Accurate linear-array dispersion imaging of passive surface waves in urban environments

Passive surface-wave methods are gaining more and more attention in near-surface geophysical and geotechnical applications. The key to the success of surface-wave methods is accurate dispersion imaging. In urban environments, a linear receiver array is commonly used for dispersion analysis for its high efficiency and low cost. Non-ideal distribution of noise sources can lead to inaccurate imaging results. For obtaining accurate phase-velocity estimation with a linear array, we propose a new workflow for dispersion imaging. Two schemes are used for handling nonuniform source distributions. With three-component data, the source azimuth can be determined and utilized for apparent velocity correction during dispersion imaging. Without three-component data, the strength of the stationary-phase-zone sources is estimated by single-component data and used for the stacking of crosscorrelations. Two synthetic examples demonstrate that the proposed workflow is effective for accurate linear-array dispersion imaging when noise sources are nonuniformly distributed. Our workflow would be an alternative to the applications of passive surface-wave methods in urban areas, especially for nonuniform source distribution.