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The island of Sulawesi, Indonesia, is located in a complex and tectonically active region, and has experienced tsunamis in the past. One of the major earthquake and tsunami events was the 23 February 1969 event that struck the Majene region in western Sulawesi Island. Interpretation of the historical accounts revealed that the Mw 7.0 earthquake generated strong intensity up to VIII on the Modified Mercalli Intensity scale. The earthquake was followed by an unusually high tsunami of 4 m that rapidly decayed within 25 km from the highest observation site. Hypocentre and earthquake mechanism analyses confirmed that it was an inland earthquake with a thrust mechanism. Ground motion modelling is able to reproduce the earthquake intensity but earthquake scenarios are unable to reconstruct the tsunami observations. A plausible solution to explain the tsunami report is from a combined scenario of an earthquake and a submarine mass failure of 0.5 km 3 . [ABSTRACT FROM AUTHOR]

Researchers have developed tsunami inundation models based on nonlinear shallow water equations to estimate tsunami propagation and inundation. However, their empirical results are not in perfect agreement with those of other research institutes, even though the same governing equations are used. Therefore, we quantitatively evaluated the variability of tsunami simulations in this study. Several research institutes have conducted tsunami simulations under the same input conditions using tsunami inundation models adopted for tsunami hazard assessment, resulting in a certain degree of variability among them. By examining the spatial and temporal differences in various physical quantities, we identified the characteristic topography where the variability between tsunami simulations increases. A novel method for calculating statistics from the area integrals of physical quantities was proposed to demonstrate the variability in the overall simulation results. In addition, the effects of different setting parameters and computational environments on the simulation results of a single model were evaluated. The findings of this study are expected to not only serve as a basis to verify the reliability of source codes employed by users of the tsunami inundation model, but also contribute useful technical information to advance probabilistic tsunami hazard assessment in the future. [ABSTRACT FROM AUTHOR]

Business continuity plans (BCPs) can be effective and proactive countermeasures to respond flexibly to crises caused by unexpected natural disasters such as large tsunamis. BCP guidelines for fisheries are being issued by the Fisheries Agency (Japan) and the utilization of such BCPs has been spreading in Japan. Despite the need to promote the social implementation of BCPs in the fisheries industry, there is a lack of quantitative criteria for the tsunami damage threshold of various fishing ports and facilities. In this research, we surveyed the damage to the fishing facilities from the tsunami generated by the 2011 Tohoku-oki earthquake. Data were collected on the tsunami damage for various fishery facilities and used to establish criteria for tsunami damage thresholds. In addition, tsunami damage inferred from 1506 scenarios of tsunami computations was predicted probabilistically for a model region as the Nachi Katsu'ura Fishery Port in Wakayama Prefecture. The method we developed in this research makes it possible to assess the probabilistic tsunami damage by combining a tsunami hazard assessment method with criteria for damage occurrence for fishery port facilities and equipment. [ABSTRACT FROM AUTHOR]

Tsunamis caused by submarine landslides are not accompanied by seismic waves and thus may appear at the coast without warning. In this study, detailed bathymetric surveys with a multi-narrow beam echo sounder were used to map submarine landslides on the continental shelf near Cape Muroto, in the Nankai trough off southwestern Japan. One of the surveyed submarine landslides was selected to supply dimensions for the simulation of a submarine mass movement by a two-layer flow model in which the upper and lower layers correspond to seawater and turbidity currents, respectively. The time series of seafloor deformation during this simulated landslide was used as the boundary condition to drive a tsunami simulation. The results showed strong directivity effects during tsunami generation in which pushing-dominant (positive) tsunami waves propagated seaward, in the direction of the submarine landslide, and pulling-dominant (negative) tsunami waves propagated landward. Both types of waves were strongly modified by frequency dispersion. For pulling-dominant waves, a tsunami simulation that included dispersion (Boussinesq) terms predicted greater maximum tsunami heights than a non-dispersive tsunami simulation. To avoid underestimation of tsunami heights, we recommend including dispersion terms when modeling tsunamis caused by submarine landslides for disaster planning purposes. • Bathymetric survey shows detailed features of the submarine landslide. • Two-layer flow model estimates the submarine mass movement. • Tsunamis caused by the submarine landslide are deeply affected by dispersion effects. [ABSTRACT FROM AUTHOR]