Analysis of generation and arrival time of landslide tsunami to Palu City due to the 2018 Sulawesi earthquake

Takagi, Hiroshi; Pratama, Munawir Bintang; Kurobe, Shota; Esteban, Miguel; Aránguiz, Rafael; Ke, Bowei

doi:10.1007/s10346-019-01166-y

Cited by 89 publications

(62 citation statements)

References 22 publications

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“…n,x and n, were specified as 250 and 500 m, respectively, to produce sources at each zone covering an area of ∼1 km 2 . This size is consistent with the approximate horizontal dimensions of the landslide measured by Takagi et al (2019) in zone I and the dimension of the coastal retreat analyzed in Carvajal et al (2019) ( Figure S8). The tsunami sources could have been distributed over depth, but we assume the equivalent total source can be concentrated at this location.…”

Section: Inversion For the Initial Elevation At The Tsunami Sourcessupporting

confidence: 85%

“…The time and duration of the landslides is not clear from the videos, apart from showing that they occurred after the earthquake. A video from a plane that took off shortly after the earthquake (bottom panel of Figure ) shows that landslides continued to be generated as much as 100 s after the earthquake (Omira et al, ; Takagi et al, ). Given this uncertainty, we develop an inversion approach that allows for landslide source start time and duration to vary and use the unique video‐derived time histories to solve for the tsunami initial surface elevations at the possible locations of these landslide tsunami sources.…”

Section: Landslide Tsunami Modelmentioning

confidence: 99%

“…There is ample evidence that extensive landslides occurred along the coast of Palu Bay. Takagi et al (), for instance, conducted near shore topographic and bathymetric surveys in the southwestern section of Palu Bay. They found evidence of a significant landslide with an area of

\sim

1 km

^{2}

, which may be related to the generation of tsunami waves, as reported by eye‐witnesses.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the Sources of the 2018 Palu, Indonesia, Tsunami Using Videos From Social Media

et al. 2020

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The 2018 Palu tsunami contributed significantly to the devastation caused by the associated MW 7.5 earthquake. This began a debate about how the moderate size earthquake triggered such a large tsunami within Palu Bay, with runups of more than 10 m. The possibility of a large component of vertical coseismic deformation and submarine landslides have been considered as potential explanations. However, scarce instrumental data have made it difficult to resolve the potential contributions from either type of source. We use tsunami waveforms derived from social media videos in Palu Bay to model the possible sources of the tsunami. We invert InSAR data with different fault geometries and use the resulting seafloor displacements to simulate tsunamis. The coseismic sources alone cannot match both the video‐derived time histories and surveyed runups. Then we conduct a tsunami source inversion using the video‐derived time histories and a tide gauge record as inputs. We specify hypothetical landslide locations and solve for initial tsunami elevation. Our results, validated with surveyed runups, show that a limited number of landslides in southern Palu Bay are sufficient to explain the tsunami data. The Palu tsunami highlights the difficulty in accurately capturing with tide gauges the amplitude and timing of short period waves that can have large impacts at the coast. The proximity of landslides to locations of high fault slip also suggests that tsunami hazard assessment in strike‐slip environments should include triggered landslides, especially for locations where the coastline morphology is strongly linked to fault geometry.

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Section: Inversion For the Initial Elevation At The Tsunami Sourcessupporting

confidence: 85%

Section: Landslide Tsunami Modelmentioning

confidence: 99%

\sim

1 km

^{2}

, which may be related to the generation of tsunami waves, as reported by eye‐witnesses.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling the Sources of the 2018 Palu, Indonesia, Tsunami Using Videos From Social Media

et al. 2020

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“…Although a comparison of bathymetric data surveyed before and after the earthquake over the whole Palu Bay was reported, it was concluded that the resolution of the pre-earthquake data was not high enough to clearly identify the location of the submarine landslide (Frederik et al 2019). The local survey in the southwestern part of Palu Bay was done, and the differences between bathymetric data before and after the earthquake were reported (Takagi et al 2019). However, in our tsunami simulation based on the bathymetric change data (model J, Table 1), the result does not explain video-inferred waveforms and the distribution of tsunami run-up heights enough (Additional file 1: Figure S5).…”

Section: Comparison With Source Models and Seabed Surveys Of Previousmentioning

confidence: 99%

“…Coastal collapses at multiple locations were also reported (International Tsunami Survey Team (ITST) 2018; Arikawa et al 2018;Sassa and Takagawa 2019). Seafloor bathymetric surveys after the earthquake were also conducted (Frederik et al 2019;Takagi et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Submarine landslide source models consistent with multiple tsunami records of the 2018 Palu tsunami, Sulawesi, Indonesia

Nakata

Katsumata

Muhari

2020

Earth Planets Space

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Previous studies have suggested submarine landslides as sources of the tsunami that damaged coastal areas of Palu Bay after the 2018 Sulawesi earthquake. Indeed, tsunami run-up heights as high as 10 m determined by field surveys cannot be explained by the earthquake source alone although the earthquake is definitely the primary cause of the tsunami. The quantitatively reexamined results using the earthquake fault models reported so far showed that none of them could fully explain the observed tsunami data: tsunami waveforms inferred from video footage and the field survey run-up tsunami height distribution. Here, we present probable tsunami source models including submarine landslides that are consistent with the observed tsunami data. We simulated tsunamis generated by submarine landslides using a simplified depth-averaged two-dimensional model. The estimated submarine landslide model consisted of two sources in the northern and southern parts of the bay, and it explained the observed tsunami data well. Their volumes were 0.02 and 0.07 km 3. The radius of the major axis and the maximum thickness of the initial paraboloid masses and the maximum horizontal velocity of the masses were 0.8 km, 40 m and 21 m/s in the northern bay, and 2.0 km, 15 m and 19 m/s in the southern bay, respectively. The landslide source in the northern bay needed to start to move about 70 s after the earthquake to match the calculated and observed arrival times.

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A tsunami generated by a strike-slip event: constraints from GPS and SAR data on the 2018 Palu earthquake

Simons

Broerse

Shen

et al. 2022

Preprint

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A devastating tsunami struck Palu Bay in the wake of the 28 September 2018 M w = 7.5 Palu earthquake (Sulawesi, Indonesia). With a predominantly strike-slip mechanism, the question remains whether this unexpected tsunami was generated by the earthquake itself, or rather by earthquake-induced landslides. In this study we examine the tsunami potential of the co-seismic deformation. To this end, we present a novel geodetic data set of Global Positioning System and multiple Synthetic Aperture Radar-derived displacement fields to estimate a 3D co-seismic surface deformation field. The data reveal a number of fault bends, conforming to our interpretation of the tectonic setting as a transtensional basin. Using a Bayesian framework, we provide robust finite fault solutions of the co-seismic slip distribution, incorporating several scenarios of tectonically feasible fault orientations below the bay. These finite fault scenarios involve large co-seismic uplift (>2 m) below the bay due to thrusting on a restraining fault bend that connects the offshore continuation of two parallel onshore fault segments. With the co-seismic displacement estimates as input we simulate a number of tsunami cases. For most locations for which video-derived tsunami waveforms are available our models provide a qualitative fit to leading wave arrival times and polarity. The modeled tsunamis explain most of the observed runup. We conclude that co-seismic deformation was the main driver behind the tsunami that followed the Palu earthquake. Our unique geodetic data set constrains vertical motions of the sea floor, and sheds new light on the tsunamigenesis of strike-slip faults in transtensional basins.

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Analysis of generation and arrival time of landslide tsunami to Palu City due to the 2018 Sulawesi earthquake

Cited by 89 publications

References 22 publications

Modeling the Sources of the 2018 Palu, Indonesia, Tsunami Using Videos From Social Media

Modeling the Sources of the 2018 Palu, Indonesia, Tsunami Using Videos From Social Media

Submarine landslide source models consistent with multiple tsunami records of the 2018 Palu tsunami, Sulawesi, Indonesia

A tsunami generated by a strike-slip event: constraints from GPS and SAR data on the 2018 Palu earthquake

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