Geology and slope investigation using resistivity method in Kg. Bukit Selar, Jeli Kelantan

Geological mapping and resistivity survey were carried out in Kuala Balah district mainly covered by Kg. Bukit Selar, Jeli Kelantan. Slope failure phenomenon is a common natural hazard in Malaysia in which due to change in slope angle, weakening of earth materials due to the weathering, increased in water content, heavy rainfall distribution and overloading. The objectives of this study were to produced geological map of study area with the scale of 1:25,000, to analyze the subsurface factors of slope failures by using Electrical Resistivity Imaging (ERI) method, and to determine type and direction of failure by using kinematic analysis method. Geological mapping in the study area has shown that the area is mainly composed of granitic rocks (microgranite and porphyritic granite) overlain by the Quaternary alluvial deposits. The Schlumberger and Pole-Dipole arrays with a maximum electrode spread of 200 m was conducted by placing five resistivity lines on slope failure along the road direct to TNB Pergau Hydroelectric power station. The data were collected by using ABEM Terrameter LS electrode selector system, and processed by using RES2DINV software. The results were presented in the form of two-dimensional (2D) resistivity profiles providing a view of the subsurface distribution of the granitic rock, geological structures, and water content. The results show that the slope failed due to the presence of seepage. Kinematic analysis was conducted as the additional method by analyzed the structural geology of the rock slope using stereonet and the result obtained were type and direction of the slope failure. The findings of this study show that all the methods, geological mapping, resistivity, and kinematic analysis are reliable for slope investigation.