Bengkulu city, located in the western part of Sumatra, is characterized by the prevalence of alluvial deposits. In certain areas, local site effects on soft alluvial sediments such as clay, sand, silt, mud, and gravel can amplify ground movements caused by significant seismic waves. Consequently, a comprehensive site effect study was conducted with closer measurement points to establish a more detailed seismic microzonation. In order to evaluate how the soil reacts to seismic activity, the HVSR method is performed to analyze the ambient soil noise within the study area. Field measurements reveal variations in the predominant frequency (ranging from 0.4 to 16.5 Hz), HVSR amplification (ranging from 0.3 to 12.3), and Kg distribution (ranging from 0.02 to 239.26), respectively. Furthermore, the PGA Kanai method was utilized to estimate soil shear strain (GSS) in the study area, using data from the 2000 Bengkulu-Enggano Earthquake (Mw 7.9) and the 2007 Bengkulu-Mentawai Earthquake (Mw 8.4). The analysis indicated a consistent distribution of Kg values with GSS and PGA values, alongside Modified Mercalli Intensity (MMI) values, exhibiting correlation coefficients greater than 0.9. This suggests that Bengkulu City faces a moderate to high vulnerability to severe damage from earthquakes. The closer examination of HVSR data at finer measurement points aids in identifying exposure to new hazards and contributes valuable insights for formulating regional planning policies centered on disaster risk reduction and enhancing existing strategies in Bengkulu City.

This paper analyses liquefaction potential in a high seismic region in Bengkulu City, Indonesia. The liquefaction hazard map, derived from the liquefaction potential index using site investigation data and geophysical surveys, is presented. The study begins with collecting site investigation data and measuring geophysical parameters. Peak ground acceleration and potential seismic damage are estimated. Liquefaction potential analysis is based on site investigation data and maximum estimated peak ground acceleration. The integrated map represents the depth-weighted analysis, and the factor of safety, also known as the liquefaction potential index, is discussed. Results indicate the predominance of sandy soils in the study area, prone to liquefaction. Coastal and river channel areas, characterised by loose sandy soils, exhibit high liquefaction potential. The study area is also expected to experience strong motion, potentially reaching intensity level IX on the Modified Mercalli Intensity scale, indicating liquefaction susceptibility during strong earthquakes. Overall, the study results offer recommendations for local government spatial planning development.