Full wavefield seismic modeling and source parameter inversion in three-dimensional viscoelastic, anisotropic media

A full wavefield seismic modeling algorithm for general 3-D anisotropic media produced by two intersecting systems of aligned cracks is developed and applied to the study of shear wave splitting at zero offset. Measurements of splitting are performed directly from synthetic multicomponent seismograms. The transition from one symmetry system to another for such cracked media is visible in the splitting behavior. Synthesized surface and VSP seismograms for cracked multi-layered media show the difficulties in identifying the splitting when propagation occurs in media with different crack orientation. A realistic model of a carbonate reservoir includes complexity in both anisotropy symmetry and structural geometry of the geological model; its response is controlled by the orientation of the anisotropy.; Full waveform inversion is used to estimate the strike, dip, rake, and scalar moment defining a point dislocation source in a 3-D viscoelastic, anisotropic medium. The forward problem produces the wavefield, of an arbitrary double couple, by linear combination of the Green's functions corresponding to the five components of the moment tensor. Effects of the 3-D structure, the attenuation, and the azimuthal anisotropy on the estimation of earthquake source parameters are quantified in a synthetic example for a realistic model of the San Fernando basin, Southern California. The approach is applied to real data for two aftershocks of the 1994 Northridge, California earthquake. Use of the 3-D structure in the estimation considerably improves the uniqueness of the solution, compared to estimations using only 1-D models. However, attenuation and anisotropy are not yet enough well known to contribute to improvement of the solutions.; Orientation of an impact source is determined from multicomponent land exploration seismic data. Parameterization of the source is simpler than that for a dislocation source, consisting of the source strength, and two angles defining the orientation of the impact. The wavefield of an arbitrarily oriented impact is represented by linear combination of the Green's functions corresponding to three orthogonal impact sources. Effective vertical and horizontal impacts derived from data for two inclined impacts in northeast Texas show significant (11–23°) deviations from the expected directions.