Simulation of thermoelastic wave propagation in 3-D multilayered half-space media

Thermal phenomena are common in both the generation and propagation of seismic waves. To investigate the propagation characteristics of thermoelastic waves generated by point sources in a 3-D multilayered half-space, herein, we develop a method that can solve problems involving coupled mechanical and thermal motions. The method first transforms the governing equations into two sets of first-order ordinary differential equations with a unified form in the frequency-wavenumber domain and then solves them by a generalized reflection and transmission coefficient method. To verify the correctness of our method and the corresponding computer program, we compare our solutions with analytical solutions. We further apply the method to different multilayered models, and the numerical results clearly demonstrate the reflection and transmission phenomena of thermoelastic waves within the interlayer. Furthermore, the generated thermal and seismic signals are synchronous, and the two P waves predicted by generalized thermoelastic theory can be converted into each other. The records on the ground show that thermal motions influence our observation of direct waves, especially in the presence of high thermal conductivity subsurface media, it can significantly impact the propagation of both body and surface waves, making surface seismic observations more complex than those predicted by elastic theory.