Numerical Modelling of Acoustic–Elastic Coupled Equation in Vertical Transversely Isotropic Media

Numerical simulations of fluid–solid coupled media are vital for marine seismic exploration. Anisotropy in real strata and the limitations of standard elastic wave equations in simulating pressure components in marine seismic data (e.g., towed streamer 1C and ocean-bottom 4C data) necessitate alternative approaches. We propose an acoustic–elastic coupled equation for vertical transverse isotropic (VTI) media overlying fluid layers, eliminating the need for explicit boundary handling. Numerical results indicate that the proposed method has slightly higher computational and storage costs compared to standard elastic wave equations. However, the synthetic seismograms preserve converted wave information, which is crucial for S-wave velocity inversion, and effectively simulate Scholte waves at fluid–solid boundaries in shallow marine environments. The equation is highly adaptable, accommodating various marine seismic acquisition methods and providing valuable insights into processing complex marine seismic data.