ABSTRACT

On September 28 2018, an Mw 7.5 strike-slip earthquake occurred to the north of Palu Bay on the Sulawesi Island, Indonesia. This triggered a destructive tsunami within the bay, which reached Palu city. Simulation have been conducted to investigate the landslide source. However, the tsunami should be investigated considering a physical model in the area where detailed bathymetric survey had not been conducted. In this study, we investigated the impact of coastal landslides on the southern part of the bay using a two-layer model. Owing to the increasing collapse volume, the southern west coastal landslide could approximately explain the observations in Palu city. However, the calculated mass volume of the source largely overestimated the bathymetric survey data. Hence, we considered the possibility of submarine landslide in the southern part of the bay and the simulation results could approximately explain the maximum tsunami heights in the southern part of the bay. These results suggest that more detailed multibeam data will be required to investigate the possible submarine landslide in the southern area which could induce a destructive tsunami reaching Palu city within a few minutes after the collapse.

摘要

2018 年 9 月 28 日，印度尼西亚苏拉威西岛帕卢湾以北发生 7.5 级走滑地震。这引发了海湾内的破坏性海啸，海啸到达了帕卢市。已经进行了模拟以调查滑坡源。但是，应该在未进行详细水深测量的地区考虑使用物理模型来调查海啸。在这项研究中，我们使用两层模型调查了沿海滑坡对海湾南部的影响。由于坍塌量的增加，西南沿海滑坡可以大致解释帕卢市的观测结果。然而，源的计算质量体积在很大程度上高估了测深调查数据。因此，我们考虑了海湾南部发生海底滑坡的可能性，模拟结果可以大致解释海湾南部的最大海啸高度。这些结果表明，需要更详细的多波束数据来调查南部地区可能发生的海底滑坡，这可能会在坍塌后几分钟内引发破坏性海啸到达帕卢市。