Abstract: A method for determining seismic anisotropy of subsurface rock formations includes measuring passive seismic signals at a plurality of locations above an area of the Earth's subsurface to be surveyed. The compressional- and shear-wave arrival times from at least one origin location of a seismic event occurring in the subsurface are determined from the measured seismic signals. The arrival times are inverted to obtain values of the seismic anisotropy parameters.