Geoscience Investigation on National Road Failure at Lugatoi Area, Viqueque Municipality, Timor-Leste

Has been carried out multidisciplinary methods in investigating road failure at Lugatoi area. The road failure has been conducted frequent maintenance within three years. Drone mapping shows discontinuity shape of morphology reflect the structural geology. Lithological, the road failure is located precisely on clay material which is product diapiric mélange. Various size of alien block of rock embedded into the clay observed along the river, this rare in landslide location. The mélange possible has relationship to the strike-slip fault that linear to discontinuity shape. Topographically, the road failure is located on a slope has values 45-50 degree. Vertical Electrical Sounding inversion show at depth 0.5 m to 30 has lowest resistivity value. This well correlated to geology observation, very wet clay and weathered siliceous argillite. Laboratory analysis reveal the result agreeable to geological condition. Further geophysical survey recommended to obtain detail subsurface information prior to maintenance construction. Avoid high slope for alternative road due to high plasticity on a high slope prone to road failures.