The Effect of Various Peak Ground Acceleration Level in Petobo Irrigation Canal Area Post 2018’s Liquefaction Disaster

Abstract

The soil liquefaction disaster in Petobo, Central Sulawesi, caused massive terrain damage. With a total displacement of up to 800 meters and a total sliding area of 1.43 km2, the soil structure was deformed. The 7.5 Mw earthquake with the maximum PGA of 0.45 was causing flow-induced liquefaction with a distance from the crown to the foot of the landslide as far as 2 km. The research aims to find out how well the post-earthquake soil can withstand the potential to liquefaction if it is hit by various earthquake levels. This research will conduct several simulations to determine the soil performance against earthquakes. The empirical calculation method is carried out by referring to Idris-Boulanger to determine the liquefaction safety factor. Based on several scenarios that have been carried out, post-earthquake land can be re-liquefy when shaken by an earthquake with a certain level below the magnitude of the 7.5 Mw 2018’s Palu earthquake. There are a total of six different scenarios of earthquakes with various level of PGA. The soils still have the possibility to liquefy with the PGA of 0.20 and can be considered safe as the PGA value of 0.13. Mitigation efforts, including soil remediation, must be carried out before reconstructing phase of the Petobo irrigation canal starts.