Identification of slip surface based on geoelectrical dipole-dipole in the landslides hazardous area of Gedangsari District, Gunungkidul Regency, Province of Daerah Istimewa Yogyakarta, Indonesia

Abstract

Landslides problems that often occurred at Mertelu Village, Gedangsari District, Gunungkidul Regency, DIY are caused by several factors. In addition to the fact that the village is located in a fairly steep area, there is also a slip surface from the existing soil type. The purpose of this research is to gather the slip surface information based on resistivity method using Dipole-dipole configuration. The initial stage is done by taking 4 representative lines, which each line is 300 meters long, spaced 20 meters and using n = 1-8. The results showed that rock resistivity varied from 2 to 200 Ohm-m also divided into very low, low, medium and high resistivity. The interpretations are very low resistivity (2-8 Ohm-m) as claystones and or siltstones, low resistivity (8-20 Ohm-m) as muddy sandstones, medium resistivity (20-50 Ohm-m) as sandstones and high resistivity (> 50 Ohm –m) as massive sandstones. In general, the bedding begins with a very low resistivity at the top and high resistivity at the bottom. The slip surface is marked as a very low resistivity which lays above a higher resistivity. The landslide analysis indicates that the Gedangsari area is dominated by rotational landslide.