A method is described for of creating a high-resolution velocity model of a geological medium that includes generating a long-wavelength anisotropic velocity model using tomographic inversion of seismic data gathers and combining the long-wavelength velocity model with an attenuation model. The method further includes performing prestack depth migration on the seismic data gathers using the long-wavelength velocity and attenuation model to produce seismic image gathers, applying a dip-consistent filter to the seismic image gathers, and transforming the filtered seismic image gathers to the time domain. The method further includes generating a full-band impedance model by performing impedance inversion of the time-domain filtered seismic image gathers using the long-wavelength velocity and attenuation model. The full-band impedance or velocity model is calibrated in the frequency domain in a manner independent of the spatial coordinates. The full-band impedance or velocity model is used for detecting fluid pressure anomalies in the geological medium.