Time-Efficient and Frequency-Independent Absorbing Layers for Seismic Wave Propagation in unbounded media

The numerical simulation of wave propagation in unbounded media, such as seismic applications, requires special techniques to avoid spurious reflections at the boundaries of truncated computational domains. In this paper, a frequency-independent and time-efficient approach on the basis of the concept of Absorbing Layers with Increasing Damping (ALID) is investigated for modeling seismic wave propagation in unbounded domains. Its performance is validated through theoretical study and numerical analysis. The absorbing domain is integrated in time using Central Difference (CD) scheme to avoid system solving and reduce the computational time. A dedicated stability analysis confirms the preservation of the critical time step in the proposed absorbing layers, in contrast to the classical Rayleigh damping approach. Satisfactory accuracy and efficiency of the proposed method has been highlighted in various numerical examples carried out in MATLAB with different types of excitations including both synthetic loadings and real seismic inputs. This approach offers clear advantages over traditional Rayleigh ALID, including frequency-independent attenuation, relatively stable time step in explicit schemes and lower computational cost.