Analysis of Soil Seismic Response in Bengkulu Using Mentawai Earthquake Scenario

Mira Fitriyani; Lindung Zalbuin Mase; Hardiansyah Hardiansyah; Rena Misliniyati; Khairul Amri

doi:10.17509/wafi.v11i1.555

Authors

Mira Fitriyani Departement of Civil Engineering, University of Bengkulu, Indonesia
Lindung Zalbuin Mase Geotechnical Hazard Research Unit, Faculty of Engineering, University of Bengkulu, Indonesia
Hardiansyah Hardiansyah Departement of Civil Engineering, University of Bengkulu, Indonesia
Rena Misliniyati Departement of Civil Engineering, University of Bengkulu, Indonesia
Khairul Amri Departement of Civil Engineering, University of Bengkulu, Indonesia

DOI:

https://doi.org/10.17509/wafi.v11i1.555

Keywords:

Soil seismic response; Vs30 Soil amplification; Ground motion; Mentawai earthquake.

Abstract

Bengkulu is a province that has a high earthquake hazard level due to the influence of the Sumatra subduction zone, the Mentawai megathrust, and active fault systems. Previous studies have mostly focused on regional earthquake hazard assessment, whereas site-specific studies of soil seismic response in Bengkulu remain lacking. The purpose of this study is to evaluate the seismic response of Bengkulu’s soil using the Mentawai earthquake scenario by combining the Vs₃₀parameter with one-dimensional nonlinear soil response analysis. The Mentawai scenario was selected because the region is a potential seismic gap that may potentially affect Bengkulu due to its geographical proximity. Ground motion input was developed using Cone Penetration Test (CPT) data, Vs₃₀values, NGA-Subduction analysis, and spectral matching for four study sites: Mukomuko, Ketahun, Ratu Samban, and Manna. The results of the study show that the Peak Ground Acceleration (PGA) values at the surface are in the range of 0.0002 to 0.0009 g with amplification factors from 1.20 to 3.15. The low PGA values indicated attenuation due to the earthquake source distance of 326-602 km. The results of this study indicate that local soil properties have an important role in amplification characteristics and surface seismic response and therefore can provide useful information for earthquake mitigation and planning of earthquake-resistant infrastructure in Bengkulu Province.

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