Methods and systems are presented in this disclosure for semblance-based anisotropy parameter estimation using isotropic depth-migrated common image gathers. Far-offset image gathers can be generated from seismic data associated with a subterranean formation migrated based on an isotropic depth migration that uses an isotropic velocity model. Based on the far-offset image gathers, a plurality of semblance values can be calculated as a function of an anisotropy parameter of the subterranean formation for the different depths and the surface locations. Effective values of the anisotropy parameter of the subterranean formation can be then chosen that result in maxima of the plurality of semblance values for the different depths and the surface locations. Anisotropy model of the subterranean formation can be obtained based on the effective values of the anisotropy parameter.