Geological constraints for disaster mitigation model in South Sulawesi

Abstract

South Sulawesi is one of the provinces in Indonesia with the highest economic growth index. This situation gives an impact to intensive infrastructure development including road access, bridge, dam, airport, seaport and other public facilities in the province. However, due to geological complexity of the region, the infrastructures developments are threatened by natural hazard. This paper outlines the characteristic of natural disaster in South Sulawesi using geological consideration of the region for mitigation strategy. The natural hazard in South Sulawesi consists of earthquake, landslide, tsunami and flood. Earthquake occurs in association with some major faults such as Walanae Fault, Palu-Koro Fault and Matano Fault. All areas located near these fault zones are classified as earthquake-prone areas. Landslides are classified as slides, flow and rock fall and takes place in some high topography areas which composed of moderately to highly weathered volcanic product material. Geologically the landslides are closely related with morphology, stratigraphy and structure (seismic-related) condition. Some coastlines in South Sulawesi province are tsunami-prone area, especially the area facing to the seismically-active region such as southern tip of the peninsula where tsunami is generated by the Flores back-arc thrust fault. Flooding shows a strong relationship to geological condition in the area especially low-lying topographic areas in some coastlines and river mouth areas. Three main causes of the flood have been considered namely deforestation due to land conversion, high sedimentation rate and sporadic urbanization coupled with heavy rain fall and tides. The study shows that all natural disasters in South Sulawesi are mainly controlled by geological condition such as fault, morphology, stratigraphy, petrology and seismicity. Therefore, in order to mitigate these natural hazards, geological constraints should be taken into consideration in natural hazard mitigation scheme in the regional level.