The September 28th, 2018, Tsunami In Palu-Sulawesi, Indonesia: A Post-Event Field Survey

On September 28th, 2018, a powerful earthquake (M-w 7.5) struck the Island of Sulawesi in Indonesia. The earthquake was followed by a destructive and deadly tsunami that hit the Bay of Palu. A UNESCO international tsunami survey team responded to the disaster and surveyed 125km of coastline along the Palu Bay up to the earthquake epicentre region. The team performed 78 tsunami runup and inundation height measurements throughout the surveyed coastline. Measured values reached 9.1m for the runup height and 8.7m for the inundation height, both at Benteng village. The survey team also identified ten large coastal sectors that collapsed into the sea of Palu Bay after the earthquake. The distribution of the measured tsunami data within Palu Bay exhibits a clear localised impact suggesting the contribution of secondary non-seismic local sources to the generation of the tsunami. Findings of the field reconnaissance are discussed to provide an insight into the remaining debated source of the Palu tsunami.