Seismic Waveform Tomography - the Effect of Layering and Anisotropy

P092 SEISMIC WAVEFORM TOMOGRAPHY: THE EFFECT OF LAYERING AND ANISOTROPY Summary 1 We describe the waveform tomographic inversion of seismic crosshole data from the Nimr field in Oman. Our initial ray-theoretical inversions of the traveltimes suggest a low level of P-wave anisotropy as do our initial long-wavelength waveform inversion results. Higher resolution 2-D waveform inversions that include this low level of background anisotropy are successful in modelling the observed data but the velocity models are smoother than expected. Surprisingly similar waveform inversions that do not include any anisotropy are also successful in modelling the observed data. These latter inversions yield