Revealing Submarine Landslide Signatures in South Western Palu Bay: Insights from New Shallow Bathymetric Data

¹ Tsunami and Disaster Mitigation Research Center (TDMRC), Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia
² Department of Marine Sciences, Faculty of Marine and Fisheries, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia
³ Research Center for Marine Sciences and Fisheries, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia
⁴ Civil Engineering Department, Faculty of Engineering, Universitas Syiah Kuala, Banda Aceh, 23111, Indonesia
⁵ State College of Meteorology, Climatology, and Geophysics of the Republic of Indonesia (STMKG), Tangerang, 15221, Indonesia

^* Corresponding author: haekal.azief.haridhi@usk.ac.id

Abstract

The 2018 Palu earthquake and tsunami was a rare event where tsunami generation was partly driven by coastal and submarine landslides triggered by a supershear Mw 7.5 strike-slip earthquake. While much attention has focused on the seismic source, the role of submarine slope failure remains less understood. To investigate this, a shallow bathymetric survey was conducted in 2024 by TDMRC and STMKG, covering over 500 km² in the central to southern parts of Palu Bay using a portable multibeam echo sounder (MBES). The bathymetric data were analyzed using slope angle and Factor of Safety (FS) modeling via Scoops3D. Several potential submarine slide features were identified, including steep scarps, chaotic seafloor patterns, and low FS zones, particularly along the offshore extension of the Palu–Koro Fault. Key slide locations, such as Benteng (A) and further south (D), are consistent with earlier post-tsunami findings. These results support the interpretation that multiple submarine landslides likely contributed to tsunami generation. The study highlights the need to incorporate landslide hazards into tsunami models and demonstrates the effectiveness of low-cost, portable MBES systems for submarine hazard assessment in Indonesia’s tectonically active coastal areas.