Landslide investigation using self potential method and electrical resistivity tomography (Pasanggrahan, South Sumedang, Indonesia)

Abstract

Landslide is a geological event that occurs because the movement of slope-forming material in the form of soil, rock or combination of material type to a lower place due to the influence of gravity. The trigger factor of landslide in Pasanggrahan, South Sumedang, Indonesia is the increase of water content in the slope and the slip plane. The slip plane began to actively to turn on when the rainy season arrives. The infiltration of rainwater into slopes as an avalanche trigger can be detected by Self Potential (SP) method. SP measurements were performed to determine changes in subsurface water flow. SP data acquisition using fixed base technique and leap frog technique. The rocks in the research area that serve as the slip plane are clays associated with Volcanic Breccia. One of the geophysical methods that can identify the slip plane is the Electrical Resistivity Tomography Method. The ERT method can detect slip plane based on rock resistivity. Based on the local geology that has been correlated with the value of Self Potential and Electrical Resistivity Tomography, the following results are obtained: water table : (1 - 13) Ohm.m and SP value : (16 - 50) mV, clay : (72 - 100) Ohm.m and volcanic breccia: (171 - 550) Ohm.m.