Determination of shear surface of landslides using electrical resistivity tomography

Abstract

Geophysical methods offer a broad spectrum of information by dealing with
slope deformations. The electrical resistivity tomography (ERT) method is mainly applied
for spatial localization of the landslide body and depicting the shear zone position. This
article presents the application of the ERT method for the landslide hazardous areas by
means of numerical modelling. Four different synthetic models with very small resistivity
contrast (30 Ohm.m/50 Ohm.m), where each model represents a different type of slope
deformation, were tested by several factors affecting the final inverse model: measurement
point density, L1 and L2 norm and L-norm roughness filter components. The higher measurement
points density helps mainly to detect the boundaries at greater depths. Inverse
models computed using the L1 norm bring satisfactory results for compact anomalous
bodies, i.e. water saturated landslide body. In the case of subtle conductive zones, i.e.
shear planes, the L2 norm based inversion is recommended. For enhanced reconstruction
of skewed anomalous objects, roughness filter including a diagonal component produces
more accurate inverse image. The article also demonstrates the ability of the ERT method
to detect and describe the shape of the slope deformation even by a relative subtle resistivity
contrast.