Ground motion, liquefaction and hazard analysis at the Palu site during the 2018 Indonesian great earthquake (Mw 7.5)

The research findings on the ground motion and liquefaction potential analyses during the 2018 Great Indonesia Earthquake (Mw 7.5) are significant and crucial. The earthquake triggered soil-structure damage due to liquefaction. This study, which thoroughly investigated four sites at Palu, was conducted by performing a comprehensive ground motion parameter analysis. The ground motion characteristics were presented and justified, particularly for the most impacted direction. Ground motion predictions were analysed to define the spectral accelerations, and matching spectral accelerations were conducted to produce ground motions for each site. Non-linear seismic ground response analysis based on the hyperbolic model of pressure pressure-dependent was performed to investigate cyclic soil behaviour. The results revealed that ground motion is crucial in significant soil damage, and the earthquake energy could trigger deep liquefaction. As the most significant ground motion, the vertical ground motion is essential in determining deep liquefaction. The discussion on the impact of liquefaction based on the results of the numerical analysis is presented. Significant ground motion with a longer duration could have a substantial impact on deep liquefaction in the study area. These findings depict how the 2018 Indonesia Earthquake (Mw 7.5) triggered a mega-liquefaction in Palu City. The results could enhance the understanding of the importance of seismic hazard assessment. It is recommended that site investigation and soil improvement should be planned to counteract liquefaction damage before construction. This study also suggests conducting seismic hazard assessments for city development to minimise the potential disaster impact in the study area.