Elastic Wave Stratigraphic Imaging Method for Impedance Relative Perturbation

Elastic seismic data record the wavefield response to perturbations of subsurface elastic properties relative to a background medium. Imaging the corresponding responses can reveal the location, polarity and continuity of subsurface anomalies, providing physically interpretable attributes for stratigraphic characterization and anomaly delineation. However, conventional migration primarily emphasizes structural reflectivity, whereas fully iterative elastic inversion is computationally demanding and affected by multiparameter coupling. We therefore develop an elastic stratigraphic imaging (ESI) method based on reconstruction of the perturbation-induced virtual source. Under the Born approximation and a local plane-wave representation in a smooth isotropic background, modal projection yields a relative-perturbation matrix parameterized by P- and S-wave impedance and density, whose radiation coefficients describe the angle-dependent material sensitivities of the elastic modes. Compensation of the temporal factor in virtual-source generation increases the relative contribution of recorded low frequencies, favouring the broader-scale components of the impedance relative-perturbation response. Without explicit angle-domain decomposition, the resulting PP and PS images represent an approximate reconstruction of finite-band and acquisition-weighted elastic modal responses. Numerical experiments demonstrate the capability of ESI for elastic-impedance relative-perturbation imaging without iteration, with physically interpretable stratigraphic attributes for anomaly characterization.