Slope stability analysis during an earthquake in flow-slide affected area of Jono Oge

Abstract

On September 28th, 2018, the earthquake with a moment magnitude (Mw) 7.5 due to strike-slip Palu-Koro Fault in Central Sulawesi caused a major geological failure. In the Jono Oge area, the earthquake-induced liquefaction and flow-slide occurred on relatively flat ground with an average slope of 2%. In this paper, the safety factor for slope stability analysis was determined by shear strength reduction caused by the earthquake at the potentially liquefied soil layer, varying peak ground acceleration values, and groundwater level conditions. This analysis evaluated the potential of ground movement occurrence in Jono Oge with the condition of soil layer pre and post the Palu-Donggala earthquake that happened in 2018 using GeoStudio Slope/W geotechnical software. The analysis was conducted on the cross-section of the soil layer based on three boreholes incorporating standard penetration test (SPT) data on the study area. The analysis results showed ground movement potential because of the seismic loads and groundwater level conditions. The lower the safety factor of slope stability, the higher the ground movement potential in flow-slide affected area. This ground movement potential could trigger the occurrence of flow-slide in Jono Oge area.

Assessment of post-liquefaction potential in soil displacement on irrigation canal reconstruction project in the Jono Oge and Lolu area, Central Sulawesi, Indonesia

“…The September 28, 2018, seismic event substantially influenced the Sigi Regency's geological state, especially in the Jono Oge village. The occurrence of liquefaction and flow-slide over the relatively flat terrain of Jono Oge was a direct consequence of the earthquake [11]. The village of Jono Oge, situated in the Palu basin, exhibited the highest degree of land displacement compared to other regions [12].…”

Geotechnical Assessment of Sublake Slopes and Liquefaction Hazard in Lake Toba, Indonesia

“…Lakefront in a high seismic activity can lead to certain effects, including slope failures, liquefaction, and soil mass deformation. These occurred as a result of slope instability [4,5]. The soil characteristics in coastal or lakefront areas are predominantly loose sandy soils, potentially enhancing the likelihood of liquefaction [6,7].…”