The seismic responses and its Doppler effects of moving aircraft caused by Acoustic-Seismic Coupling

When the acoustic waves interact with the ground, seismic waves can be generated. These seismic waves are influenced by the incident angles of acoustic waves and the near-surface seismic-wave velocities. To understand the acoustic-seismic coupling signals, we designed a hard-stratum model (where the transverse wave of the subsurface velocity is higher than acoustic wave velocity) and a soft-stratum model (where the transverse wave of the subsurface velocity is lower than acoustic wave velocity) for acoustic-seismic signals simulation. We employed the hybrid Galerkin method to simulate the acoustic-seismic signals generated by moving acoustic sources. We then validated the existence of Rayleigh and evanescent waves induced by the acoustic-seismic coupling process. Even in high-attenuation subsurfaces, relatively high-amplitude seismic waves can still be received underground at a depth of 200 m. When the transverse wave of the subsurface velocity is greater than the acoustic wave velocity, the surface geophone detects four kinds of seismic waves: longitudinal, transverse, Rayleigh, and evanescent waves. We could successfully capture the Doppler frequency shift phenomenon in both the generated seismic waves and acoustic waves. Moreover, the velocities of both these waves can influence the shape of the Doppler curves.