Covergent plate margin tectonice depends critically on the physical properties which control the mechanical state and style of deformation. Porosity, permeability, pore pressure and sediment strength are important rock properties which influence the deformation response. In 1987 the PI's collected 7 expanding spread profiles (ESP's) and 5 split spread profiles (SSp's) across the Nankaj Trough off Japan. The ESP's and SSP'shave been inverted for compressional wave velocity using travel-time information. The PI's now propose to implement two full waveform inversion techniques and apply these to ESP and SSP data from the Nankai Trough. They will apply both a layer-stripping inversion method and an iterative forward modeling cheme to evaluate their performane. These inversions will result in a more detailed estimate of compressional wave velocity, density, and possibly shear wavy velocity. These quantities will then be used to construct two transects of sediment physical properties in the zone of maximum strain near the base of the trench.
