General geology mapping and application of geophysical methods for slope mitigation at Manek Urai, Kelantan.

The moving mass or landslide and the failure mechanism can affect the planning of engineering projects, such as highway and railroad cuts, retaining walls etc. The unexpected landslide commonly occurs and it can harm people surround it. Therefore, this study is to identify the information about the soil profile and rock on slopes that have been selected as they have enough potential gradients to landslide or slope failure to occur. Study area is located in the village of Manek Urai, District of Kuala Krai, in the state of Kelantan Darul Naim. Rocks that found here are igneous rocks, sedimentary rocks and metamorphic rocks. The objectives of these studies were to characterize the material at the study area with geophysical techniques. For electrical resistivity method, a total of three survey lines were done with the length of 100 m for each survey line while for the seismic method, 3 line surveys with the length of 60 m was carried along the face of the slope and across the survey line for electrical resistivity method. The subsurface investigated was approximately 3 m to 15 m. Electrical resistivity method can show the weathered profile from the weathered layer until bedrock. Thickness of the weathered layer is 3 m to 5 m with resistivity value ranging from 0.0 am to 3500 am. and the resistivity value more than 3500 am. was predicted as hard rock or bedrock. For seismic method, 3 main layers were observed by the velocity of waves that propagates through different earth material. The 2-D imaging shows different value of velocity and we can interpret each layer by the existing colour. Normally, the purple and blue colour shows the low velocity while the yellow and red colour shows high velocity of wave. The average thickness of the 1st layer is 3 meters and it considered as top soil. The second layer has a wave velocity around 1500 m/s to 3500 m/s. This layer consists of weathered profile with some specific grade. This layer has a average thickness of 5 meters to 7 meters and the 3rd layer consists of hard rock known as the bedrock which have a wave velocity 3500 m/s and above.