Spatial analysis of the liquefaction vulnerability zone based on the phreatic level at the Palu groundwater basin, Central Sulawesi Province

Abstract

An earthquake with a magnitude of 7.4 in Palu City and Donggala District in Central Sulawesi Province on September 28, 2018 has caused a liquefaction disaster. Basically liquefaction can occur in earthquake prone areas, shallow phreatic depth and poorly consolidated soil. This study attempts to examine the relationship between phreatic depth and the probability of liquefaction. The research method is an analog and numerical relation model, by combining the aquifer system model and groundwater geographic information system with landuse patterns in areas affected by liquefaction disasters. This method is described in Spatial and Environmental Analysis, which is supported by the use of satellite imagery and the analysis process with the Arc View Gis 3.3 program. The results showed that there was an influence between rainfall on the spatial distribution of phreatic depth, with the average rainfall in the Palu area being 68.74 mm / month and the depth of phreatic level ranged from medium (2.5 - 7.0 meters from ground level) - shallow (<2.5 meters from ground level). Based on the phreatic depth of the Palu groundwater basin, the chances for liquefaction are in the medium to high zone class.