Consideration of submarine landslide induced by 2018 Sulawesi earthquake and tsunami within Palu Bay

Nagai, Kaori, Muhari, Abdul, Pakoksung, Kwanchai, Watanabe, Masashi, Suppasri, Anawat, Arikawa, Taro and Imamura, Fumihiko (2021) Consideration of submarine landslide induced by 2018 Sulawesi earthquake and tsunami within Palu Bay. Coastal Engineering Journal, 63 (4), 446-466. (doi:10.1080/21664250.2021.1933749).

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.

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Contributors

Author: Masashi Watanabe

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