First Results of a Bathymetric Survey of Palu Bay, Central Sulawesi, Indonesia following the Tsunamigenic Earthquake of 28 September 2018

摘要

On 28 September 2018, a 7.7 Mw strike-slip earthquake struck Central Sulawesi at 0.18 degrees S, 119.85 degrees E, similar to 10 km northwest of Palu, the capital of Central Sulawesi Province, affecting more than 230,000 people. The rapid arrival of the wave suggests a tsunami source within Palu Bay. A bathymetric campaign was conducted in Palu Bay and the region south of Cape Manimbaya from 9 to 18 October 2018. One of the goals was to identify a potential source for the tsunami. The bathymetry data show a prominent submarine channel within Palu Bay with sinuosity controlled by the Palu-Koro Fault. The submarine channel continues into deeper water south and west of Cape Manimbaya with a sinuosity index of up to 1.770. Several submarine slumps were identified within the bay, due to the arcuate head scarp, the abrupt change in slope and debris on the seafloor, or the undulating shape of the slope. One possible source location near the mouth of Palu Bay is identified from the estimated volume of displaced sediment. The bathymetry data also show traces of the Palu-Koro Fault and suggestions of uplift of Cape Manimbaya related to activity of the Palu-Koro Fault.