f DETECTING BLIND FAULTS USING RAYLEIGH WAVE REFLECTIVITY

Finding faults near the surface is important for construction and engineering applications. It is difficult to locate them because there is often no surface expression, i.e. they are blind faults. We have developed a novel method for extracting Rayleigh wave reflectivity from sharp boundaries and tested it on modeled and field data. Rayleigh waves are particularly suited to detecting blind faults because of their presence extending into the shallow subsurface. Others have studied the complex wavefield due to heterogeneous impedance contrasts in the near surface scattering Rayleigh waves into P, S, and other Rayleigh waves. However, if contrasts are conformed to a boundary, such as a fault, scattered waves give way to reflected waves and a less complex wavefield. To find reflectivity, we determine phase velocity and amplitude for the outgoing Rayleigh wave and deconvolve the reflected wave with the outgoing wave while in a phase matched domain.