PALU-TYPE LIQUEFACTION (A Unique Natural Phenomenon in the World, A Comprehensive Geological Review)

The earthquake and subsequent liquefaction that occurred in Palu City and its surrounding areas on September 28, 2018, had a devastating impact, particularly in the Petobo, Balaroa, and Jono Oge areas. Based on post-disaster data, the recorded death toll reached 2,081 people, with the highest number of victims in Palu City (1,706 people) as reported by BNPB as of October 25, 2018. Palu-type liquefaction is a unique and specific phenomenon that occurs in the Palu region, particularly in the Balaroa and Petobo areas, in the form of massive soil flows formed by the complex interaction of geological, hydrogeological, and tectonic factors. This event was triggered by a combination of alluvial fan conditions with loose lithology, the presence of pressurized aquifers, and the formation of vertical fractures due to tectonic activity, which together resulted in destructive post-earthquake ground flows. Through the studies of sedimentation, structure and tectonics, hydrogeology, and engineering geology presented in this book, it is hoped that it will become a strategic reference for policy makers, academics, disaster practitioners, and the wider community in understanding the risks of liquefaction and developing appropriate mitigation measures. The Geological Agency, as part of the Ministry of Energy and Mineral Resources, which focuses on the investigation and service of energy and mineral resources, is committed to continuously striving to protect the community from various geological disasters.