Analisis Potensi Likuefaksi di Kota Bengkulu Berdasarkan Kecepatan Gelombang Geser
DOI:
https://doi.org/10.29303/goescienceed.v7i4.3113Keywords:
Bengkulu City; Factor Of Safety; Liquefaction; Shear-Wave VelocityAbstract
This study maps the spatial variation in average shear-wave velocity to a depth of 30 m (Vs30) and evaluates liquefaction potential in Bengkulu City. The analysis used Multichannel Analysis of Surface Waves (MASW) data from 137 measurement points acquired by BMKG in 2022. Surface-wave records were reprocessed through dispersion-curve picking and inversion to obtain shear-wave velocity profiles to 30 m. Liquefaction potential was evaluated to 23 m using corrected shear-wave velocity (Vs1), cyclic stress ratio (CSR), cyclic resistance ratio (CRR), and factor of safety (FS). The analysis adopted an Mw 8.9 earthquake scenario, bedrock peak ground acceleration of 0.60 g, surface peak ground acceleration of 0.66–0.72 g, and groundwater depth of 0.5 m. Vs30 ranged from 85.6 to 488.9 m/s. Values of FS ≤ 1 occurred at 102 locations (74.5%), with 97 locations first reaching this threshold at depths of 1–5 m; the overall initial depth ranged from 1 to 17.9 m. Thirty-five locations did not show FS ≤ 1, including 30 outside the empirical calculation domain. Geological, CPT/SPT, historical, and two-dimensional cross-section comparisons showed consistency with documented liquefaction in Lempuing.
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