2D Electrical Resistivity Tomography Of An Active Landslide: A Case Study From Ain Torki, Algeria.

Landslides are widespread in many mountainous regions of Algeria. Hazardous Landslides start to appear in the slope of Ain Torki village, just after the construction of new buildings. The main triggering factor in the study area is water flow down-slope in the near-surface aquifer until reaching the top of the impermeable marls. Human activities can also play an important role in affecting the susceptibility of a slope to failure, especially in the Ain Torki region, where slopes are extensively urbanized and farmed for agriculture. 2D electrical resistivity tomography has been applied to characterize the internal geometry of the slide. We used an ABEM Terrameter LS Imaging System with a multi-electrode system and Wenner-Schlumberger configuration with an array of 64 electrodes. The results of four Wenner-schlumberger lines covering the landslide are presented. For each line, more than 977 measurements were acquired with an electrode spacing of 3 and 5 m respectively. The sliding surface is interpreted as the limit between the relatively high resistivity mobilized material and the underlying conductive marls. These results are in agreement with the lithological data from boreholes, which show a depth to unweathered marls of about 10-15 m.