The potential of liquefaction disasters based on the geological, CPT, and borehole data at Southern Bali Island

Abstract

Following the incident in Petobo, Palu, liquefaction becomes an essential object for in-depth study. Based on soil investigation by the CPT (cone penetration test) in site soil test has been carried out at Jalan Taman Pancing, the area of Southern Bali Island was analyzed for liquefaction potential using geological interpretation and soil properties. Deterministic analysis using Stress Based Method, using the 2017 Seismic Hazard Map of Indonesia for Bali island where the earthquake acceleration reaches 0.4 - 0.5 g, meaning that Bali is highly vulnerable to earthquake, with the largest earthquake magnitude is the Mount Agung eruption measuring six on the Richter scale on May 18, 1963. The soil investigation shows that the layers of soil consist of sandy silt and silty clay at a depth between 0.5 - 12.0 m and 2 m water table, geological conditions with the Qa code alluvium deposits from ancient Buyan-Beratan Mountains. Deterministic analysis based on the CPT data and local geological conditions indicates that the thickness of the soil varies between 1.5 m and 9.5 m, while the safety factor of the liquefaction potential is in the critical conditions between 1.25 - 1.00.