Field Survey of the 2018 Sulawesi Tsunami Deposits

Putra, Purna Sulastya; Aswan, Aswan; Maryunani, Khoiril Anwar; Yulianto, Eko; Kongko, Widjo

doi:10.1007/s00024-019-02181-9

Cited by 33 publications

(16 citation statements)

References 19 publications

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“…Similar results were computed for each type of simulation: 1) the envelope of maximum surface elevations over the study area and runups along the Palu Bay coastline, to be compared with measurements from field surveys (Pribadi et al, 2018;Mikami et al, 2019;Omira et al, 2019;Putra et al, 2019;Widiyanto et al, 2019), in Figures 3,9,11, for the coseismic, landslide, and dual sources, respectively (runups computed in both the coarser BG and finer SG/EG grids are provided, whereas envelopes are computed using the finer resolution results, wherever available); and 2) time series of surface elevations computed at locations where various observations or measurements were made or inferred, i.e., Wani, Pantoloan, Dupa, Talise, KN Hotel, and Grand Mall ( Figure 1B), in Figures 4,10,12, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…We compare the results to a more comprehensive database of post-tsunami field survey results, including runups, tsunami elevations at the Pantoloan Port tide gauge together with those inferred at other locations from a novel analysis of the tsunami videos (Carvajal et al, 2019). From tsunami timing information in the aircraft pilot and other videos, we infer that there was a short delay in the triggering of the landslides by the earthquake, that FIGURE 3 | (A,C) Runups R (black dots) measured in Palu Bay by international teams (Pribadi et al, 2018;Mikami et al, 2019;Omira et al, 2019;Putra et al, 2019;Widiyanto et al, 2019) we use in modeling and show that this improves the agreement with observations.…”

Section: Figure 1 | (A)mentioning

confidence: 94%

“…Study area with base model grid (BG) over Palu Bay (white box), epicenter location (USGS, 2018, yellow star), and traces of local faults used in earthquake source models by: (blue) Jamelot et al (2019), (red) Socquet et al (2019), and (green) Ulrich et al 2019; (B) Footprint of BG with locations of (red dots) measured runups (Pribadi et al, 2018;Mikami et al, 2019;Omira et al, 2019;Putra et al, 2019;Widiyanto et al, 2019) (black dots) surface elevation time series inferred from shore-based videos (Carvajal et al, 2019, GM, grand mall; KN, KN Hotel; T, Talise; D, Dupa; P, Pantoloan; W, Wani) (yellow dots) observed landslides, (diamond) location of aircraft at 10:04:33 UTC, that filmed coastal landslides ( Figure 2).…”

Section: Figure 1 | (A)mentioning

confidence: 99%

“…In the months following the event, international research teams conducted field surveys, recording earthquake and tsunami damage, landslides, and tsunami runup and inundation. Red dots in Figure 1B mark locations of runups collected by Mikami et al (2019); Omira et al (2019); Pribadi et al (2018); Putra et al (2019); Widiyanto et al (2019) (note only data labeled as runup in these references was used). Earthquake shaking, tsunami generation (particularly by coastal landslides; e.g., Figure 2), and various tsunami impacts were recorded in many amateur videos posted on social media, that were collected and analyzed (e.g., Carvajal et al, 2019), providing critical information on the timing and sequence of events.…”

Section: Introductionmentioning

confidence: 99%

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New High-Resolution Modeling of the 2018 Palu Tsunami, Based on Supershear Earthquake Mechanisms and Mapped Coastal Landslides, Supports a Dual Source

2021

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The Mw 7.5 earthquake that struck Central Sulawesi, Indonesia, on September 28, 2018, was rapidly followed by coastal landslides and destructive tsunami waves within Palu Bay. Here, we present new tsunami modeling that supports a dual source mechanism from the supershear strike-slip earthquake and coastal landslides. Up until now the tsunami mechanism: earthquake, coastal landslides, or a combination of both, has remained controversial, because published research has been inconclusive; with some studies explaining most observations from the earthquake and others the landslides. Major challenges are the numerous different earthquake source models used in tsunami modeling, and that landslide mechanisms have been hypothetical. Here, we simulate tsunami generation using three published earthquake models, alone and in combination with seven coastal landslides identified in earlier work and confirmed by field and bathymetric evidence which, from video evidence, produced significant waves. To generate and propagate the tsunamis, we use a combination of two wave models, the 3D non-hydrostatic model NHWAVE and the 2D Boussinesq model FUNWAVE-TVD. Both models are nonlinear and address the physics of wave frequency dispersion critical in modeling tsunamis from landslides, which here, in NHWAVE are modeled as granular material. Our combined, earthquake and coastal landslide, simulations recreate all observed tsunami runups, except those in the southeast of Palu Bay where they were most elevated (10.5 m), as well as observations made in video recordings and at the Pantoloan Port tide gauge located within Palu Bay. With regard to the timing of tsunami impact on the coast, results from the dual landslide/earthquake sources, particularly those using the supershear earthquake models are in good agreement with reconstructed time series at most locations. Our new work shows that an additional tsunami mechanism is also necessary to explain the elevated tsunami observations in the southeast of Palu Bay. Using partial information from bathymetric surveys in this area we show that an additional, submarine landslide here, when simulated with the other coastal slides, and the supershear earthquake mechanism better explains the observations. This supports the need for future marine geology work in this area.

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Section: Resultsmentioning

confidence: 99%

Section: Figure 1 | (A)mentioning

confidence: 94%

Section: Figure 1 | (A)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

New High-Resolution Modeling of the 2018 Palu Tsunami, Based on Supershear Earthquake Mechanisms and Mapped Coastal Landslides, Supports a Dual Source

2021

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“…Indeed, on 28th of September 2018, an Mw 7.5 earthquake occurred and ruptured the fault with up to 7 m left-lateral offset, extending 180 km and traversing Palu City (Bao et al 2019;Socquet et al 2019). It was shortly followed by a 4-to 7-m-high tsunami, possibly associated with submarine landslides (Putra et al 2019;Sassa and Takagawa 2019;Takagi et al 2019). According to many earthquake catalogs (e.g., United States Geological Survey (USGS); Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG); German Research Centre for Geosciences (GFZ); Global Centroid-Moment-Tensor (GCMT)), the hypocenter was located in Donggala Regency, about 80 km to the north from Palu City and at a depth of 10-15 km.…”

Section: Introductionmentioning

confidence: 99%

Development of the Palu–Koro Fault in NW Palu Valley, Indonesia

Patria

Putra

2020

Geosci. Lett.

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The 220-km-long Palu-Koro Fault, Central Sulawesi, is a major fault with prominent expression in Eastern Indonesia. Many studies about the Palu-Koro Fault have shown its capability of generating large earthquakes, but how the Palu-Koro Fault has evolved remains enigmatic. This study is to investigate the geomorphology of NW Palu Valley based on DEMNAS (Digital Elevation Model of Indonesia) and field observations to understand the development of the Palu-Koro Fault. The study area comprises a high mountain in the west and a valley in the east. There are two major normal faults and a strike-slip fault observed in NW Palu Valley. The western normal fault is a basin-bounding fault, which marks the topographic break between mountain and valley. To the east, another normal fault is observed cutting the old alluvial fans and expressed by planar fault scarps. The strike-slip fault is observed within the basin and crosses the distal part alluvial fans. It is expressed by intra-basin ridges in places which are slightly uplifted from the adjacent surface. The surface rupture of the 2018 Mw 7.5 Palu earthquake in NW Palu Valley also shows left-lateral movement up to 4 m. We consider that the development of the Palu-Koro Fault in NW Palu Valley is characterized by toward-centralbasin migration of faulting activity from basin-bounding fault to intra-basin fault.

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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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Field Survey of the 2018 Sulawesi Tsunami Deposits

Cited by 33 publications

References 19 publications

New High-Resolution Modeling of the 2018 Palu Tsunami, Based on Supershear Earthquake Mechanisms and Mapped Coastal Landslides, Supports a Dual Source

New High-Resolution Modeling of the 2018 Palu Tsunami, Based on Supershear Earthquake Mechanisms and Mapped Coastal Landslides, Supports a Dual Source

Development of the Palu–Koro Fault in NW Palu Valley, Indonesia

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

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