Seismic coupling of interface modes in sedimentary basins: A recipe for disaster

Abstract Coupling between an evanescent P wave and a Rayleigh wave can occur when the two modes share the same phase velocity at an interface. The result is a new, distinctive monochromatic mode of large amplitude and finite duration that may reverberate in a bounded layer, generating stationary patterns due to constructive and destructive interference. Such modes may be responsible for earthquake damage in the Valley of Mexico and perhaps in other sedimentary basins vulnerable to seismic disasters on soft ground.