Geology and analysis of slope stability using electrical resistivity imaging (Eri) in Lojing, Gua Musang, Kelantan

Lojing is located at Gua Musang district. The research objective is to update geological map of study area at Lojing, Gua Musang with a scale of 1: 25,000. The research second objective is to analyse slope stability of the study area by using Electrical Resistivity Imaging (ERI). In general, geological mapping include stratigraphy, structural geology, geomorphology and lithology of the study area. Rock samples were taken for purpose of petrographic analysis in laboratory. ArcMap 10.2 is used in digitizing and updating the geological map. The study area is consisted of rocks from Triassic period which are limestone, sandstone, mudstone, calcareous mudstone, tuffaceous mudstone, and siltstone interbedded with shale. Study area is cover with Gua Musang Formation. Geomorphology of the study area are mostly consisted of hilly area and mountainous area. There is no main river in the study area. For geophysical study, there were six survey lines at three different location of slopes. Two lines were conducted horizontally using Wenner array for 200 meters. Two lines were also conducted horizontally with Schlumberger array for 200 meters and the other two lines were conducted vertically using Pole — dipole array in 80 meters and 100 meters. ABEM Terrameter Lund System (LS) was used in geophysical survey. The current was injected to the subsurface through 41 electrodes. Based on the obtained data from the survey, the slope 1 and slope 3 become unstable due to presences of weathered rocks and the presence of water in the rock strata that disturb the pore pressure. Point load test is suggested to estimate rock strength and will produce more accurate justification about slope stability of an area.