Liquefaction Risk Assessment and Microzonation in Bengkulu Port Area After a Megathrust Earthquake

This paper looks at the risks of liquefaction and microzonation in the port area of Bengkulu City after a major earthquake. The study began by collecting existing data on shear wave velocity (V_s) and included new data from measuring ambient noise to calculate Vs. The researchers also measured the actual groundwater levels on-site. They investigated 30 locations to get a complete picture of the area. The analysis focused on the most likely earthquake in the region, which was the M_w 8.6 Bengkulu-Mentawai Earthquake in 2007. The study used numerical methods with an effective stress model and empirical methods based on site investigation data to assess the ground settlement related to the liquefaction factor of safety (FS) and the probability of liquefaction (PL). The study provided a micro-zonation of settlement to give an overall view of the area. It also suggested a simple model to predict liquefaction parameters based on FS and PL. The findings showed that groundwater is found at depths between 0.35 and 3.51 m below the ground surface. Five locations showed potential for liquefaction at depths of less than 5 m. The thickness of the liquefied layer varies from about 1.5 to 2 m, and the total settlement ranges from 1.10 to 2.87 cm. The predictive models for liquefaction potential can be widely used in engineering, and the results of this study are expected to influence future infrastructure planning in Bengkulu City.