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On January 1 2024, at 16:10 JST, an earthquake of Mw 7.5 occurred underneath the Noto Peninsula of Ishikawa Prefecture, Japan. This event caused a cascading disaster impact on cities in the Noto Peninsula through a series of strong earthquake shakes, strong ground motions, slope failures, liquefaction, fire, and tsunamis. The tsunami first reached Suzu City a few minutes after the earthquake, eventually affecting approximately 340 km of the coast from the Ishikawa to Niigata Prefectures. The Coastal Engineering Committee of the Japan Society of Civil Engineers conducted an organized post-event field survey to understand the impact of tsunamis on land. This study summarizes the post-event field survey results and provides a general understanding of tsunami behavior and damage using measured tsunami inundation and run-up heights. [ABSTRACT FROM AUTHOR]

In this study, a real-time tsunami estimation method was developed using the linear superposition of Green's functions, which account for nonlinear tsunami effects around coastal areas. To this end, first, the nonlinear effects associated with the inundation and bottom friction and advection terms in a nonlinear long-wave model were investigated, focusing on large tsunamis around Urado Bay in Kochi Prefecture, Japan, which is at risk of future damage from tsunamis produced by the Nankai Trough earthquake. The results indicate that the effects of advection play a more significant role than those of the inundation and bottom friction in terms of accurately estimating near-shore tsunami propagation. Then, based on these results, Green's functions were modified to account for the linearly approximated effects of the advection terms. By applying the developed method to tsunamis around Urado Bay, it was demonstrated that accurate estimations of the water surface level and flow velocity changes could be quickly obtained at any location around the bay. The developed method can be applied to real-time tsunami inundation forecasting and off-shore evacuation simulations of vessels to support optimal evacuation decisions. [ABSTRACT FROM AUTHOR]

The increase in the magnitude of natural disasters has led to the development of risk assessment methodologies to indicate risk levels in qualitative terms. Among these, the Source-Pathway-Receptor-Consequence (SPRC) methodology assesses the risk from the source of the hazard to the possible consequences. In the present work, an economic evaluation was carried out on the substantial damages directly associated with the floods generated by a 10 m high tsunami off the coast of Zihuatanejo, Mexico. This event was identified as the worst-case scenario of tsunamis associated with a 8.4 Mw earthquake. The method followed was the SPRC, with an economic evaluation, applied to street level in Zihuatanejo. The economic costs were obtained from the results of this work using a criterion to characterize the percentage of damage to various types of housing and goods associated with different levels of flooding. This work is intended as a basis for the better planning of urban development, considering possible economic damage from tsunamis. It also provides a more objective perspective for distributing funds for mitigating natural disasters, allowing aid to be directed to the areas and types of housing with greatest risk from the flooding. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of a new discrete V-shaped coastal barrier (V-wall) to reduce multiple tsunami-bore impacts on a group of idealized coastal structures. The performance comparison has been made between a baseline model (BM), continuous straight wall models (SW), and V-wall (VW) models. A number of key parameters including the barrier height and length along with the arrangement of the landward structures are investigated numerically using the 3-D smoothed particle hydrodynamics (SPH) approach. From the SPH models output the bore velocity, maximum force, total impulse, and pressure distribution on the structures are examined. The results indicate that the V-walls can provide a similar level of protection to continuous seawalls of the same height and hence can be considered as an economic alternative to protection in tsunami prone regions. However, in order to gain the greatest benefit from the V-walls, strategic planning of the position and orientation of landward structures and the walls themselves are needed to avoid bore flow focusing and reflection effects. [ABSTRACT FROM AUTHOR]

The 2011 Great East Japan Earthquake and Tsunami are one of the most catastrophic natural disasters that took place in Japan. The disaster caused widespread destruction to the estuarine and coastal areas along the northeastern region of Japan. The Abukuma River mouth, among many estuaries in Miyagi Prefecture, suffered major damage from the tsunami in which the sand spit and the sand terrace were severely eroded. The present study aims to provide a better comprehension of the morphology of the Abukuma River mouth within a decade after the 2011 tsunami based on the collected datasets of imagery and offshore bathymetry surveys. The consecutive changes of the sand terrace and sand spit indicate their connection influencing the morphological recovery in the Abukuma River mouth. About a year after the tsunami, the sand terrace re-appeared by a flood event and became the sediment source to recover the sand spit under the intrusion process. When the sand spit almost recovered and achieved a stable configuration, the sediment from the sand terrace into the river was restricted. As a result, more sediment from the sand terrace was expected to be transported to the downdrift area under the dominant wave condition in the Abukuma River mouth. [ABSTRACT FROM AUTHOR]

The 2011 Tohoku Tsunami caused severe damage to many coastal defenses along the Japanese coastline, including areas where two adjacent upright sea dikes of different heights met. There are many places along the coastline where structures of different heights and shapes meet due to the various design codes. In this study, the authors aim to examine the tsunami flow around such dikes by conducting three-dimensional hydraulic experiments in a tsunami wave basin and numerical simulations using the fluid dynamics model OpenFOAM. Twelve experimental cases were tested by changing the waveforms, and also by keeping the height of one side of the dike model constant while adjusting the dimensions of the other side. The results show that the difference in height between the structures significantly influences the volume of overtopping over the relatively lower dike and the inundation depth and velocity behind the dikes. Furthermore, different characteristics of inundation patterns are observed between the inundation depth and velocity. Hence, this study illustrates the necessity to re-assess the effectiveness of such structures against tsunami events. [ABSTRACT FROM AUTHOR]

A fragility function shows the building damage likelihood based on a demand parameter such as the tsunami flow depth. While empirical fragility functions have been developed by using postdisaster damage survey data, regions with no recent tsunami damage cannot develop these estimations. Alternatively, analytical fragility functions could be developed to fill this gap. Along the Colombian Pacific coast, several tsunami events have occurred; however, the aftermath resulting from the structure physical damage was not recorded. Fortunately, other regions of the have collected tsunami damage information, which has been analyzed and represented in terms of empirical fragility functions. This paper provides a comparative study of empirical and analytical tsunami fragility functions. It is focused on the analytical fragility functions developed for typical structures in Tumaco, Colombia and on empirical fragility curves taken from damage survey data of recent tsunami events. The differences in the assessments of the damage produced by the two methods in the case of a two-story reinforced concrete building in Tumaco is discussed herein. As a result of the comparison, it was shown that the structures in Tumaco have higher collapse probabilities at lower flow depths than structures in other places along the Pacific and Indian Oceans. [ABSTRACT FROM AUTHOR]

The extreme typhoon Lan caused devastating damage to the Seisho Coast of Japan in 2017. This study presents nearshore wave measurements conducted at different locations along the shore and numerical hindcasts to elucidate the extreme wave field during the typhoon focusing on infragravity wave dynamics, which was comparable in magnitude to incident short waves in shallow water. During the peak of the typhoon, there was a significant wave height of ~8 m, and the infragravity wave height exceeded 2 m at a 14 m depth. The measurement data suggest that infragravity waves developed as bound waves from incident wave groups and partially dissipated during the typhoon peak in the surf and swash zones through their energy transfer to high-frequency waves. Numerical wave hindcasting models successfully reproduced the measured extreme wave field and indicated that the wave refraction over Oiso Spur caused an incident wave concentration in the severely damaged area where high waves collapsed a seawall during the typhoon. Moreover, infragravity waves also exhibited significant alongshore variation, which was due to the different bottom slopes and incident short-wave properties. This study identifies several key features that may have caused the localization of significant damage along the Seisho Coast. [ABSTRACT FROM AUTHOR]

Tsunamis can cause large damage to breakwaters and other protection structures placed along the coastline. The strong flows generated by such waves can move the armor units of composite breakwaters, leading to large impact forces on the caissons behind them. In the present work laboratory experiments were carried out in a flume to determine the forces that can result from such impacts. Then, an empirical equation that would allow the estimation of these forces was proposed, with the aim of facilitating the construction of returning walls and parapets situated on top of caissons. [ABSTRACT FROM AUTHOR]

To improve the applicability of numerical simulations in tracking debris motion for probabilistic assessments of debris collisions with buildings and components installed in coastal industrial sites at a local scale (O (1 km)), the applicability of the numerical approach is investigated through numerical simulations of laboratory experiments. Two characteristic phenomena are found that cannot be expressed by the numerical simulations. The first characteristic phenomenon is debris motion approaching a building model in a reflected wave. To simulate this phenomenon, the incorporation of a turbulent bore model into the numerical model is proposed. The second characteristic phenomenon is debris diffusion due to various perturbations. For simulation of this phenomenon, two approaches are proposed. In the first approach, some causes of debris diffusions are separately modeled. In the second approach, diffusions due to various perturbations are simulated by artificially intensifying debris diffusions. By investigating impacts of the two approaches on probabilistic assessments of debris collision, it is found that debris spreads and the exceedance probabilities of collision speed can be predicted well by considering epistemic uncertainties in determination of diffusion intensity by the latter approach. [ABSTRACT FROM AUTHOR]

Following the 2011 Tohoku earthquake, coastal forests dissipated the energy of the tsunami and trapped flotsam. Although studies have shown how trees dissipate flow energy and are damaged in the process, the factors determining the trapping of flotsam by lines of trees or their capacity to do so have not been quantitatively examined. Quantitative evaluation of these factors may lead to tree-based strategies for suppressing the secondary damage caused by tsunami flotsam. To increase the ability of trees to mitigate damage, their physical limitations need to be identified. Field surveys revealed that integrated clusters of flotsam were caught by trees even if individual floating objects were smaller than the distance between the trees. Hydraulic experiments revealed relations between physical factors and the capture of flotsam. From these relations, we derived a simple formula for evaluating the trapping capacity of lines of trees. The estimates from our model were consistent with the actual results of the 2011 tsunami in Tagajo city, Miyagi prefecture, where trees did not topple under the forces applied by trapped flotsam. [ABSTRACT FROM AUTHOR]

The 2011 Tohoku Tsunami is considered to be one of the most tragic events in Japan's disaster history, and represents an important milestone for the research community regarding the investigation of the characteristics of tsunami inundation. A thorough analysis of tsunami inundation was conducted using numerical modeling, and measurements from a video recorded from the rooftop of a building in Onagawa in Miyagi Prefecture. In this study, we analyze the destruction of buildings using numerical simulations and tsunami fragility functions. Numerical results for the locations at which the tsunami eyewitness video was recorded are compared with measurements. In addition, we considered the effect of the breakwater in Onagawa bay to evaluate its contribution to reducing overland tsunami inundation depths. The results of our simulations show that the maximum inundation depth due to the first incoming wave was over 16 m, and over 500 buildings were washed away with this first wave. This result is consistent with the video data. Further, we found that the breakwater, which was not originally designed against tsunami waves, reduced the maximum tsunami inundation depth at least by 2.0 m in Onagawa town. [ABSTRACT FROM AUTHOR]

In the 2011 Tohoku Earthquake, many structures were destroyed by the tsunami whose magnitudes were much larger than the design level. Tsunami defense structures in coastal areas will need reinforcement in the future, and for that reason it is important to evaluate tsunami behavior and resulting tsunami force. This study analyzes tsunami transformation around a Haramachi thermal power station which suffered serious damage by the tsunami due to the 2011 Tohoku Earthquake and which has complex topography and building layout. A three-dimensional (3D) tsunami simulation is carried out for a surrounding region of the Haramachi thermal power station using boundary conditions of the water surface elevation and flow velocity obtained from a two-dimensional (2D) tsunami simulation by a nonlinear shallow water model. Using these boundary conditions, the computer fluid dynamic model FLUENT is employed to simulate the tsunami behavior around the Haramachi thermal power station. The validity of the predictions is examined by comparison with actual traces of tsunami inundation depths (I.D.). [ABSTRACT FROM AUTHOR]

A huge tsunami caused by the giant earthquake occurred off Sumatra in Indonesia, on 26th December 2004, attacked the coastal regions of many countries facing the Indian Ocean. This paper describes evaluation methods of structural damage in order to mitigate the damage by huge tsunamis. First, the damage by this tsunami at Patong Beach in Phuket province of Thailand is explained. Next, diagrams to get critical inundation heights which break buildings are shown by using a rigid frame model as functions of inundation heights. Then, how to get the inundation height empirically is explained. Moreover, a numerical model to simulate the inundation height is also used, because the method described previously will give inundation heights of low accuracy as geographical feature becomes complicated. Furthermore, there were some structural collapses (a masonry wall and so on) by tsunami back-flow; the stability of a concrete wall against the back-flow is also discussed. [ABSTRACT FROM AUTHOR]

The great tsunami off Sumatra Is., 2004 has led us to initiate research into a new aspect of coastal forests — their damage reduction capacity. Coastal shelterbelt plantation is a promising countermeasure to mitigate tsunami disaster, and possesses concurrent benefits for the coastal environment. This study's aim is to assess the tsunami attenuation ability of coastal forests by applying knowledge from forest science. The temporal developments of tree diameter and stand density under self-thinning conditions are discussed. An analytical formulation of the tsunami attenuation coefficient is developed based on forest growth models. Tree throw-down effect by tsunami attack is included, and the maximum tsunami attenuation is assessed in regards to the temporal development of the coastal forest. Furthermore, trunk diameter distributions are considered, and more realistic evaluations on tsunami attenuation ability of coastal forests are attained. [ABSTRACT FROM AUTHOR]

The Indian Ocean Tsunami on 26 December 2004 affected Sri Lanka, which is located 1,700 km from the epicenter. A field investigation was conducted along the southwest coast of Sri Lanka to measure tsunami trace heights, investigate the damage, and obtain correct information on the tsunami. The results of the field survey showed that the tsunami arrived on the southwest coasts two and a half hours or more after the earthquake. The average tsunami height was 5 m along the southwest coast and tsunami trace heights of 10 m were found locally. The tsunami destroyed a number of wooden and brick houses, damaged port and harbor facilities and coastal railways, washed away many vessels, and scoured the foundations of coastal structures. The port and harbor facilities such as the breakwaters, and rigid coastal houses continuing along the coast reduced the tsunami and lessened the damage that it caused. Hydraulic experiments were conducted to investigate the characteristics of tsunami flooding on flat or declining ground, since it was clarified by the field survey that the severer tsunami damage was caused at the place where the coastal land inclines inland. The experimental results show that the pressure acting on the structure on the sloping bottom was at least twice that of the flat bottom under the experimental conditions. [ABSTRACT FROM AUTHOR]