A 3-D Hybrid SEM-FK Method for Teleseismic Wave Simulation in Coupled Elastic-Acoustic Media

We present a three-dimensional hybrid numerical scheme developed for modeling teleseismic plane-wave propagation through coupled acoustic–elastic media. This approach integrates the 3-D spectral-element method (SEM) with a matrix-based frequency–wavenumber (FK) method, enabling the rigorous treatment of complex bathymetry and precise elastic–acoustic coupling within layered media. To facilitate large-scale simulations, the computational framework is optimized via GPU acceleration. The accuracy of the hybrid SEM–FK method is validated through a benchmark comparison with semi-analytical FK solutions for one-dimensional velocity structures. We demonstrate the practical utility of the method using a synthetic two-layer subduction zone model; specifically, we simulate receiver functions for ocean-bottom seismometers and perform a full-waveform inversion that successfully recovers prescribed subsurface anomalies. This hybrid SEM–FK framework provides an efficient and robust tool for receiver function analysis and scattering imaging, offering a powerful tool to investigate Earth’s deep structure beneath oceanic regions.