Soil Characterization in Landslide-Prone Areas Using Ground Shear Strain Based on Active and Passive Source Surface Wave Methods

The Black Sea Region in Türkiye, particularly Degirmendere Valley in Trabzon, is highly susceptible to landslides due to steep slopes and heavy rainfall. This study focuses on predicting landslide behavior which is highly important by characterizing soil conditions in both active and paleo-landslide areas using surface wave methods. The shear wave velocity was determined using the Multichannel Analysis of Surface Waves (MASW) and Rayleigh Wave Ellipticity (RWE) techniques. Additionally, soil parameters like predominant period, frequency, and amplification were obtained using Horizontal to Vertical Spectral Ratio (HVSR) and Standard Spectral Ratio (SSR) methods. Ground shear strains (GSS), which indicate landslide susceptibility, were also calculated. Results show that landslide-prone areas were classified as D (NEHRP). These areas indicate predominant periods of 0.83–1.35 s, site amplifications of 5–6, Vs₃₀ values between 279–458 m/s, and GSS ranging from 10^–1 to 10^–2. In contrast, non-landslide-prone areas were classified as C (NEHRP), with predominant periods of 0.12–0.53 s, lower amplifications of 1–2, Vs₃₀ values between 300 and 782 m/s, and GSS of 10^–3–10^–4. This data is critical for understanding and mitigating landslide risks in the region.