September 28, 2019 Palu, Indonesia Landslide Tsunami Simulations
Abstract
On September 28, 2018 at 10:02:44 AM UTC (6:02:44 local time) a Mw 7.5 earthquake struck the Donggala Regency in the province of Central Sulawesi, Indonesia, causing massive structural damage in the region. Almost immediately following the earthquake large tsunami waves impacted the entire coast of Palu Bay, particularly at the southern end, where the city of Palu is located. The earthquake also caused liquefaction in the Palu neighborhoods of Petobo, Balaroa, and Jono Oge, as well as landslides, recorded by a commercial pilot and several boatmen, on the west coast of the bay. The earthquake rupture was along the Palu-Koro fault, primarily with strike-slip motion, which normally would not be expected to directly generate major tsunamis. Eyewitness reports, videos of the tsunami waves, as well as tide gauge and runup data, indicated early on that a mechanism additional to the fault was required to explain the tsunamis. Multibeam bathymetry acquired in Palu Bay soon after the event showed no evidence of submarine landslides.
Numerical simulations of the tsunami based on a coseismic source alone have as yet not reproduced the observations from the event. From the field surveys, witness reports indicate that at numerous locations around Palu Bay, the earthquake was followed quickly by the tsunami. At many of these locations, there were coastal landslides, which occurred in between the two events. Here we present new numerical simulations of the tsunami based on dual mechanisms of earthquake and landslides. The landslides are sited at a number of locations around the bay, which are identified from before and after satellite imagery and field observations. The tsunami is initiated with the nonhydrostatic model NHWAVE, with propagation from the Boussinesq model FUNWAVE and the coastal impact simulated in high-resolution model grids.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH32A..02S
- Keywords:
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- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS;
- 4341 Early warning systems;
- NATURAL HAZARDS;
- 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL