Liquefaction investigation of Balaroa, Central Sulawesi on liquefied and non-liquefied areas

On September 28, 2018, an earthquake occurred in Central Sulawesi with Mw 7.5. This earthquake caused severe damage in Balaroa due to liquefaction that resulted in flow-slide that destroyed 1357 houses. Some fears arose related to the recurrence of the disaster. A study was conducted in the Balaroa liquefied area and the non-liquefied area nearby to examine the ground condition of the site that may not be appropriate for residential purposes. The investigation adopted Liquefaction-Triggering-Based Standard Penetration Test (SPT) Procedure by Idriss and Boulanger, and then was analysed further using Liquefaction Potential Index (LPI) by Iwasaki et al. Data for analysis were obtained from soil investigation at the liquefied area, i.e., at beginning and middle of the flow-slide area, and at outside of the flow-slide end which represented a non-liquefaction area. The results showed that in the liquefied area, the LPI values of 24 and 25 were categorized as very high liquefaction potential, whereas, at the non-liquefied area nearby, the LPI was found about 4 that was in the range of low liquefaction potential. High liquefaction potential conditions occur when thick layer(s) of liquefied soil is found at the upper part of the ground with 4 m or more thickness.