Landslide investigation using electrical resistivity tomography (ERT) technique at the location of water channel PLTM Lambangan, Pagimana, Central Sulawesi

Abstract

Mass movement phenomena that occur in the research area affect the destruction of water channel in the area of PLTM Lambangan that located at the location. This research aimed to investigate soil movement phenomena in order to determine control factors that causing soil prone to move, especially in the surface geological aspect and underground lithology condition in the research area. Investigation method applied is by underground geologic and geophysical surveys using electrical method, that is Electrical Resistivity Tomography (ERT) with Wenner Configuration. Results of investigation show that geological factors are quite related to the soil movement. Movement phenomena occur in the surface with hilly to steep cut topography (21-55%) with material sourced from alluviation of clastic sediment dan carbonatic rocks. The damaged area is people farming area where fibre root of plant adds water absorption capacity of the soil. Also, sliding materials show water seepage that indicates that the moving slope has been saturated. This condition supported by information from geoelectric survey which indicates that in general the under surface material potent to slide or move because of unconsolidated material with its resistivity values in the order of 16 - 43 m that estimated related to alluvial or saturated residual soil.