Landslide is a geological risk phenomenon, which take lives and caused great damages world around, mainly in mountainous and coastal regions. Landslide does not occur suddenly. In that, a process of deforming of rock’s massive was developed, accumulation of the stress, and mineralogical changes. Release of strain associated with the sliding movement of the body, which occur only in the last stage. The ability for sliding movement, as well as other events as avalanches of the stones or rocks, and their collapse, is associated directly with mechanical and geological condition of the rocks massive.
Primary targets for geophysics include compressional and shear strength of the rock and overlying sediments together with their relative clay and water composition. Geophysics methods also helpful in obtaining the material properties and boundaries of subsurface materials.
How These Geophysical Techniques Could Help?
In seismic technique,the measurement of mechanical properties of soil and rock masses can be made. If P and S waves are measured, ‘seismic E modulus’ and ‘seismic Poisson’s ratio’ can be determined:
where λ, μ are Lame’s Constant, ρ the density of material.
These mechanical properties of soil and rock masses are very useful in slope stability analysis.
Meanwhile, in electrical resistivity imaging or resistivity technique, measurement is based on the difference in resistivity between different subsurface material. This survey technique can establishes soil and rock mass movement due to present of clay materials or water.
Therefore, all of the information obtained from geophysical techniques are very useful in landslide and/or slope stability investigation.