Enhancing Fundamental Mode Interpretation in Heterogeneous Media: An Example From Canoga Park, California

Surface wave data were collected at a site in southern California to detect near-surface discontinuities. However, due to the abundance of faulted and fractured media throughout the site, clear fundamental mode Rayleigh wave dispersion patterns were difficult to obtain. To account for the apparent heterogeneity, three different processing techniques were applied to enhance the fundamental mode dispersion image and reduce higher mode interference: muting, high-resolution lateral radon transform, and dispersion-curve based FK filter. Although one method alone does not sufficently improve the fundamental mode disperion pattern in the presence of geologic heterogeneity, interpreting the enhanced dispersion images together guided picking for the fundamental mode.