DOUBLE MONOPOLE RESONANCE OF A GAS-FILLED, SPHERICAL CAVITY IN A SEDIMENT

The monopole response of a gas-filled, spherical cavity in a sediment is investigated. The sediment is either a fluid, elastic solid, or sat urated poroelastic medium. The present method entails the scattering o f an incident displacement field that preferentially excites the monop ole resonance of the cavity. The main result demonstrates that a gas-f illed, spherical cavity in a saturated poroelastic medium can exhibit two distinct monopole resonances. These resonances arise from the two distinct longitudinal modes of propagation in saturated poroelastic me dium as described by Blot's theory. (C) 1998 Acoustical Society of Ame rica.