Integrate of Geoelectric and Geomagnetic Methods to Construct Subsurface Model as Early Landslides Mitigation in Kalirejo, Kokap, Kulonprogo

Abstract

Kalirejo, Kokap, Kulonprogo area is part of Yogyakarta in the west which borders the Province of Central Java. In general, the geomorphology of this research area consists of hills with varying slopes ranging from 15^o - 60^o, lithology consists of massive andesite intrusion with intense weathering, this can be a mass movement. The study uses geoelectric and geomagnetic approaches to identify components that allow mass movement or landslides to occur. Based on the response of geoelectric data, it is known that andesite rocks that have impermeable properties can become a slide plane having a resistivity contrast between 100 - 3000-ohm meters. Geoelectric data also describes the presence of surface aquifers which can be an important component in landslides. The water-saturated lithology has a resistivity range of 10 - 40-ohm meters. Based on the analysis of geomagnetic data with a magnetic intensity value range ranging from -400 - 1400 nT, it is known that the research area has a fairly high structural intensity. Analysis of geoelectric data shows that the thickness of the unconsolidated sediment is thick enough and the layer underneath is an impermeable rock layer, so it can be concluded that has a high potential for landslides.