Geology and subsurface void risk mapping using ERI at PPMS Kesedar Sejahtera, Gua Musang, Kelantan

The study area covers 25 km2 from the total area of Gua Musang which is 7979.77 km2. The coordinate of the study area ranging for latitude from 4°48'36.38" N to 4°50'59.17" N and the longitude from 102°00'52.78 E to 101°56’51.09” E. meanwhile the specification area is between Gua Batu Boh and Gua Serai. The objective of the study is to update the geological map of the study area to 1:25000 scale to identify the potential of subsurface void using ERI and to determine limestone karst’s subsurface condition. The methods that have been used in order to update the geological map are preliminary study, sample collection while geological mapping, and field observation such as geomorphology features, land use, and drainage pattern. There were three sample of rock that selected to make a petrographic analysis. The lithology of the area mostly dominated by limestone following by phyllite sandstone interbedded with siltstone and acid intrusive. A variety of the landform makes a difference in the elevation which ranging from 100m to 500m. Geological map that has been updated using Arcgis Software. Specification in this study was involving a secondary data carried out in between and around Gua Batu Boh and Gua Serai. The data was trimmed using Res2dinv Software. Based on result from interpretation shows that there are some areas where subsurface void happened. But the areas were filled with sand and water in the void spaces. Nevertheless, the areas were still unsafe for any development activities to be carried out. Subsurface void was determined to happen in the Gua Batu Boh area.