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

Coupling between an evanescent P wave and a Rayleigh wave can occur when th e. two modes share the game 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 du e to constructive and destructive, interference. Such modes may be responsi ble for earthquake damage in the Valley of Mexico and perhaps in other sedi mentary basins vulnerable to seismic disasters on soft ground.