PALU EARTHQUAKE CASE STUDY: INDUCING AND PRINCIPLE OF ITS COUNTERMEASURES

Abstract

The Palu Earthquake disaster on Friday 28th September 2018 in Central Sulawesi of Indonesia with the scale magnitude 7.5 of Richter Scales impacted to the huge damages area with a lot of victim and other construction damages either infrastructures or irrigation channel facilities. The earthquake induced the number of disasters such as tsunami, liquefaction, landslide and subsidence and damages the human settlement, plantation and rice field. Based on geology condition which state that the earthquake location laid on the Palu-koro active Fault therefore the soil layer conditions are dominating by the sediment deposit consist of the material molasse with the loose of sandy silty clay within un-experienced depression yet or un-confined pressures. In the saturated condition will influence increasing pore water pressures due to the soils are confined by the excessively water during earthquake and probably tsunami impact. Impacting of the pore water will affect to the liquefying soil and automatically will be decreasingly the soil shear strength parameters. Based on the morphology as a gently slope with the gradient is less than 1%, the excessive pore water pressures can intensively increase and push the soil layers on above troughing the cracks or on the weak places of the molasse soils and developing the boiled sand. If the gradient slope is less than 1% will affect to the land movement or transversal landslide such as in Sibalaya and Jonooge villages, whilst in Balaroa and Petobo villages with the gradient of slope less than 1% the bearing capacity will decrease and affect to land subsidence. Therefore, based on the analysis from investigation and soil characteristics of soils which are sensible to the liquefaction potential, the countermeasure recommendations prefer with the technology for protecting the increasingly pore water pressures, such as an arrangement of drainage pattern system and stone column or Vibro compaction. 