A method for determining structure in the Earth's subsurface includes generating an initial model of the structure. The initial model includes at least one layer boundary. A wellbore is drilled along a selected trajectory through the Earth's subsurface in a volume represented by the initial model. At least one formation parameter is measured azimuthally along the wellbore. A distance is determined from the wellbore at selected positions therealong to the at least one layer boundary using the azimuthal formation parameter measurements. The initial model is adjusted using the determined distances. In one example, the parameter is resistivity. In one example, the parameter is acoustic velocity.