Identification of Earthquake-Prone Zones in West Sulawesi Province for Disaster Mitigation Using the Probabilistic Seismic Hazard Analysis (PSHA)

The West Sulawesi province is one of the earthquake-prone areas in Indonesia. One of the causes of earthquakes in this region is the presence of thrust fault associated with folds, commonly known as the Mamuju-Majene Fault Thrust Belt (FTB). This thrust fault generally moves from north to south, crossing both the sea and the land of West Sulawesi. This study aims to determine the Peak Ground Acceleration (PGA) value using the Probabilistic Seismic Hazard Analysis (PSHA) method and to analyse earthquake-prone zones based on seismic hazard curves in West Sulawesi. The study utilizes earthquake data from the BMKG and USGS catalogs for the period 1973–2023. The research stages include identifying seismic source models, characterizing seismic sources, determining the logic tree and attenuation function, also conducting Probabilistic Seismic Hazard Analysis (PSHA) in the form of hazard maps and hazard curves. The result of PSHA processing using USGS PSHA 2007 software is in hazard value on bedrock for a probability of exceedance of 2% in 50 years (earthquake recurrence period of 2475 years) yielded a range of acceleration values of 0.05–0.9 g for PGA, 0.2–2.5 g for short periods (T = 0.2 seconds), and 0.05–0.7 g for long periods (T = 1 second). The PSHA analysis indicates that high PGA values predominantly occur in North Mamuju, Mamuju, Majene and Polewali Mandar regency. This is because these three districts are closest to fault sources, including the Palukoro Fault and the Makassar Strait Fault.