Geoelectrical resistivity survey for subsurface investigation in karst area

Abstract

Karst area is vulnerable for the sinkhole disaster, especially in the area where the housing for the community was developed on it. This paper discusses the use of geoelectrical resistivity survey to investigate the possibility of void in the subsurface to avoid the sinkhole disaster in the housing area. Two geoelectrical resistivity surveys with wenner configuration have been conducted on the flat area where the limestone outcrops were found around 500 m from it. The electrodes spacing were adjusted at 2 m in order to coverage higher resolution of the electrical subsurface data. Some direct resistivity measurements have been conducted prior to the geoelectrical resistivity survey for obtaining the true resistivity value of some material in order to support geoelectrical resistivity interpretation. The results show that the resistivity value for the wet limestone is ranging from 170-240 ohm.m, while the clay material ranges from 30 to 170 ohm.m. The resistivity surveys indicate the occurrence of limestone in the subsurface at the depth 9 m downward. Generally, the geoelectrical resistivity survey can depict the possibility of the zone where the sinkhole disaster may occur in the future.