Geological Behavior (GBR)

This landslide study was conducted in Kampung Mesilou, Kundasang. Desk study, field study and data analysis used were based on recorded slides occurred in 2008, July 2013, November 2013 and June 2015. These episodic landslides have significant impact on road, concrete bridge, vegetable gardens and killed a farmer. Factors that control the slides are natural and anthropogenic activities. The natural factors include geological characteristics, weathering, excessive precipitation and natural river phenomena. Human activity is represented by unguided cutting slope for development purposes. The geological factor consists of unconsolidated Pinosuk Gravel rock unit, topography and occurrence of active northeast-southwest fault zone crossing this area. High weathering rate has weakening the underlying rock unit as well as heavy precipitation. Intermittently high energy during storm of the main river channel of Mesilou River has been increasing the rate of erosion at slope base since few decades. Natural slope was steepened during road construction and become less stable. Slope stability analysis has confirmed the slope is unstable with FOS < 1, especially during rainy session.