Analysis of slip surface by using geoelectrical array at Wonoreja Karanganyar Regency as mitigation of landslide disaster

Landslide disaster often occur in areas with hilly topography such as Wonoreja Village. The occurrence of landslides can be predicted by identifying the slip surface. Slip surface is one of the factors that can cause landslides disaster. The aims of the research is to figure out the characteristic of slip surface at Wonoreja Village. Data acquisition were conducted using geoelectrical method with Wenner-Schlumberger array. The data were obtained at 3 lines with 210 length. The data were processed using RES2DINV ver 3.54 software. We found that the slip surface for first line is around 12 meter depth with clay material that forms an inclined plan pattern which can be potential to cause translational landslide. On the second line we found two slip surfaces around 20 to 25 meter depth, the first one forms a concave pattern which can be potential to cause a rotational landslide, another slip surface on second line forms an inclined plane which can be potential to cause a translational landslide. On the third line we found an inclined plan slip surface at 15 meter depth which can be potential to cause translational landslide.