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.

Abstract: A P-wave slowness-polarization data set resolving P-wave slowness against P-wave polarization angle is extracted from a multi-offset vertical seismic profiling data set. A function relating P-wave polarization angle to P-wave slowness, and being dependent on at least three free parameters, wherein in at least two of these free parameters information of shear wave velocity is absorbed together with one or more anisotropy parameters that characterize formation anisotropy is selected, and regression values found for the at least three free parameters by fitting the selected function to the P-wave slowness-polarization data set. The regression values may be utilized in a method of producing a mineral hydrocarbon fluid from an earth formation.

Abstract: A P-wave slowness-polarization data set resolving P-wave slowness against P-wave polarization angle is extracted from a multi-offset vertical seismic profiling data set. A function relating P-wave polarization angle to P-wave slowness, and being dependent on at least three free parameters, wherein in at least two of these free parameters information of shear wave velocity is absorbed together with one or more anisotropy parameters that characterize formation anisotropy is selected, and regression values found for the at least three free parameters by fitting the selected function to the P-wave slowness-polarization data set, The regression values may be utilized in a method of producing a mineral hydrocarbon fluid from an earth formation.