Low Shear Wave Velocity Zones as Evidence for Liquefaction Susceptibility: Case Study of Building X in Mamuju

Recurrent earthquakes in Mamuju Regency in 2021-2022 triggered a co-disaster in the form of liquefaction, which had a significant impact on urban infrastructure. One case occurred in a building located near a refueling station, which experienced subsidence due to liquefaction. Post-liquefaction studies generally rely on conventional geotechnical methods, which are relatively time-consuming and costly. This study aims to evaluate the potential impact of liquefaction on buildings using a geophysical approach, specifically through cross-sectional analysis of shear wave velocity (Vs) using the Multichannel Analysis of Surface Waves (MASW) method. Data were collected using the Common Mid Point Cross-Correlation (CMP-CC) technique to obtain a better Vs cross-section resolution than the conventional MASW method. The results of the Vs cross-section interpretation allow the identification of subsurface zones that are more susceptible to liquefaction, which are indicated in areas referred to as Low Velocity Zone. This information can be used as a basis for determining areas that require special attention in geotechnical repair and mitigation efforts.