THE INFLUENCE OF EARTHQUAKE SIGNIFICANT DURATION ON LIQUEFACTION POTENTIAL IN AREA PASAR RAYA PADANG

Abstract

Pasar Raya Padang, located in a seismically active area with a history of liquefaction from the 30 September 2009 earthquake, requires a detailed liquefaction potential analysis. This study aims to determine the influence of earthquake significant duration on ground motions at the site and to address the limitations of the commonly used simplified method. Four synthetic ground motion variations were generated to reflect the site characteristics and used in non-linear numerical analyses to calculate safety factors. The results indicate that both short and long-duration earthquakes, particularly those with late maximum peak ground accelerations, significantly increase the pore water pressure ratio by 20-50%. Short-duration earthquakes with early peak ground accelerations result in higher cyclic stress ratios. Liquefaction potential was identified at depths of 12-20 meters. The study concludes that short-duration earthquakes pose a higher liquefaction risk than long-duration events. The results highlight the critical role of accurately selecting ground motions for risk assessment, which is essential for mitigating liquefaction risk in future construction projects.