Landslide characterization using P- and S-wave seismic refraction tomography - The importance of elastic moduli

The distributions of seismic wave velocities determined from SRT at the study site indicated zones with higher porosity and fissure density that are interpreted to represent the extent and depth of mass movements and weathered bedrock zones. Distinguishing the lithological units was facilitated by deriving the Poisson's ratio from the SRT data as saturated clay and partially saturated sandy silts showed distinctively different Poisson's ratios. Shear and Young's moduli derived from the SRT data revealed the weak nature of the materials in active parts of the landslide (i.e. 25 kPa and 100 kPa respectively). The SRT results are consistent with intrusive (i.e. cone penetration tests), laboratory, and additional geoelectrical data from this site. This study shows that SRT forms a cost-effective method that can significantly reduce uncertainties in the conceptual ground model of geotechnical and hydrological conditions that govern landslide dynamics.