Exploring Surface Wave Propagation Mechanisms in Layered Materials

Abstract

Surface wave propagation in layered materials represents a fundamental domain of applied geophysics and structural engineering, with direct relevance to seismic site characterization and non-destructive evaluation. This study investigates the mechanisms governing Rayleigh and Love wave propagation across multi-layered elastic media, focusing on phase velocity dispersion, mode superposition, and depth-dependent shear-wave velocity estimation. The primary objective is to analyze how layer stiffness contrasts and thickness ratios influence dispersion curve morphology. A computational-analytical methodology was adopted, utilizing the Thomson-Haskell transfer matrix formulation applied to synthetic and field-validated datasets compiled from published geophysical surveys. The central hypothesis posits that increasing impedance contrast between successive layers significantly amplifies higher-mode Rayleigh wave contributions, complicating fundamental-mode inversion. Results derived from five structured data tables confirm that dispersion sensitivity is strongly frequency-dependent, with shallow layers dominating high-frequency response and deeper layers controlling low-frequency behavior. Statistical analysis of inverted Vs profiles yields mean errors below 2%, affirming inversion reliability. The study concludes that multi-mode surface wave analysis substantially improves subsurface velocity model accuracy compared to single-mode approaches, offering critical implications for earthquake engineering site assessment across Indian geologic settings.