Tsunami Wave Impact Research Articles

Tsunami propagation and flooding maps: An application for the Island of Lampedusa, Sicily Channel, Italy

AbstractThe Mediterranean coastlines are densely populated zones which host key socio‐economic and commercial activities. For this reason, coastal areas are vulnerable sites in case of natural disasters as tsunamis that can strike coasts causing widespread damage to the population and facilities. For these reasons, several studies were performed over the last decade to study the impact of tsunami waves on the coasts. This research assessed the inundation risk due to a tsunami wave which can hit the southeastern coast of Lampedusa Island. The coastal low‐lying geomorphological setting of the southeastern part of the island led to significant socio‐economic growth, but Lampedusa falls within the Mediterranean Sea, a high‐tsunamigenic area, therefore, the need to investigate tsunami propagation and coastal flooding of this sensitive site emerged. For this scope, a calculation chain model was implemented incorporating three steps: the DELFT‐3D software for earthquake effects modelling, MIKE 21 Flow Model FM for nearshore propagation and HEC‐RAS for onshore tsunami inundation modelling. The simulations illustrate the impact of three tsunami scenarios with different magnitudes (Mw 8.5, 7.5, 6.5) generated by hypothetical earthquakes in the Hellenic Arc. In the Mw 8.5 magnitude scenario, significant flooding occurs in the harbour region, with maximum water depths reaching approximately 3.5 m. The maximum water velocity in this scenario reaches about 15 m/s in the eastern portion, adjacent to cliffs impacted by the tsunami wave. In contrast, the Mw 7.5 magnitude scenario demonstrates reduced flooded areas, with the cliffs containing the waves and preventing further flooding. Water depths and velocities in the Mw 7.5 scenario remain minimal. Changes in both propagation and flooding are not significant between scenarios Mw 7.5 and Mw 6.5. This methodology can be employed for more accurate tsunami wave simulations not only in the Mediterranean region but also in various case studies.

A parallel machine learning-based approach for tsunami waves forecasting using regression trees

Following a seismic event, tsunami early warning systems (TEWSs) try to provide precise forecasts of the maximum height of incoming waves at designated target points along the coast. This information is crucial to trigger early warnings in areas where the impact of tsunami waves is predicted to be dangerous (or potentially cause destruction), to help the management of the potential impact of a tsunami as well as reduce environmental destruction and losses of human lives. For such a reason, it is crucial that TEWSs produce predictions with short computation time while maintaining a high prediction accuracy. This paper presents a parallel machine learning approach, based on regression trees, to discover tsunami predictive models from simulation data. In order to achieve the results in a short time, the proposed approach relies on the parallelization of the most time consuming tasks and on incremental learning executions, in order to achieve higher performances in terms of execution time, efficiency and scalability. The experimental evaluation, performed on two real tsunami cases occurred in the Western and Eastern Mediterranean basin in 2003 and 2017, shows reasonable advantages in terms of scalability and execution time, which is an important benefit in a urgent-computing scenarios.

Deep neural network-based prediction of tsunami wave attenuation by mangrove forests

The goal of this research is to develop a model employing deep neural networks (DNNs) to predict the effectiveness of mangrove forests in attenuating the impact of tsunami waves. The dataset for the DNN model is obtained by simulating tsunami wave attenuation using the Boussinesq model with a staggered grid approximation. The Boussinesq model for wave attenuation is validated using laboratory experiments exhibiting a mean absolute error (MAE) ranging from 0.003 to 0.01. We employ over 40,000 data points generated from the Boussinesq numerical simulations to train the DNN. Efforts are made to optimize hyperparameters and determine the neural network architecture to attain optimal performance during the training process. The prediction results of the DNN model exhibit a coefficient of determination (R2) of 0.99560, an MAE of 0.00118, a root mean squared error (RMSE) of 0.00151, and a mean absolute percentage error (MAPE) of 3 %. When comparing the DNN model with three alternative machine learning models— support vector regression (SVR), multiple linear regression (MLR), and extreme gradient boosting (XGBoost)— the performance of DNN is superior to that of SVR and MLR, but it is similar to XGBoost.•High-accuracy DNN models require hyperparameter optimization and neural network architecture selection.•The error of DNN models in predicting the attenuation of tsunami waves by mangrove forests is less than 3 %.•DNN can serve as an alternate predictive model to empirical formulas or classical numerical models.

Nested Modeling Framework for Assessing Tsunami Wave Impact on the Coastal Region of Gujarat, West Coast of India: A Hypothetical Approach

Nested Modeling Framework for Assessing Tsunami Wave Impact on the Coastal Region of Gujarat, West Coast of India: A Hypothetical Approach

Scenario-based tsunami hazard assessment for Northeastern Adriatic coasts

Significant tsunamis in the Northern Adriatic are rare, and only a few historical events have been reported in the literature, with sources mostly located along central and southern parts of the Adriatic coasts. Recently, a tsunami alert system has been established for the whole Mediterranean area; however, a detailed description of the potential impact of tsunami waves on coastal areas is still missing for several sites. This study aims to model the hazard associated with possible tsunamis generated by offshore earthquakes, with the purpose of contributing to tsunami risk assessment for selected urban areas along the Northeastern Adriatic coasts. Tsunami modelling is performed by the NAMI DANCE software, which allows accounting for seismic source properties, variable bathymetry, and nonlinear effects in wave propagation. Hazard scenarios at the shoreline are developed for the coastal areas of Northeastern Italy and at selected cities (namely, Trieste, Monfalcone, Lignano and Grado). An extensive set of potential tsunamigenic sources of tectonic origin located in three distance ranges (namely at Adriatic-wide, regional and local scales) are considered for the modelling. Sources are defined according to available literature, which includes catalogues of historical tsunamis and existing active faults databases. Accordingly, a set of tsunami-related parameters and maps are obtained (e.g. maximum run-up, arrival times, synthetic mareograms) that are relevant to planning mitigation actions at the selected sites.

Toward the response of coastal bridges with updated RC shear key properties under the multi-hazard action of earthquakes and tsunamis

Coastal bridges are significantly endangered by the combined effects of earthquakes and tsunamis. The accurate prediction of bridge responses in such scenarios is vital to ensure their security. Reinforced concrete (RC) shear keys, which serve as sacrificial bridge components, can effectively mitigate inertial loads from superstructures, and thus safeguard pier columns. Previous research has shown that their mechanical properties can differ considerably under cyclic and persistent impacts. Therefore, this study focused on the seismic-tsunami responses of a simple-support coastal bridge equipped with RC shear keys. A horizontal failure shear key was incorporated because of its distinct performance observed previously. The OpenSees platform was employed to conduct the numerical work, with an updated material framework developed to modify the shear key behavior before the tsunami analysis. Natural ground motion records were selected to demonstrate the dynamic analysis, and the records were scaled using spectral accelerations (Sa) to account for the various damage states of shear keys resulting from superstructure collisions. The tsunami wave impact was modeled using the second-order solitary wave theory, with different wave conditions employed to consider the immersed conditions. The calculation results were compared for the bridges with and without updated shear key properties, showing distinctions in terms of time-history and maximum responses at certain seismic levels. Based on the analysis results, this study is expected to provide a reliable estimation of the seismic-tsunami responses of coastal bridges.

MODELING OF LOADS FROM TSUNAMI WAVES ON THE STRUCTURE

Currently, the improvement of methods for calculating building structures is continuing, including, among other things, methods for determining the magnitude of the load. Despite the fact that for most impacts, the principles of determining loads and methods from the application have been formed for a long time, a number of special tasks are sometimes encountered in design practice, for example, the impact of tsunami waves on a structure. This article is devoted to modeling the wave roll on a structure in the "Fluid Flow (Fluent)" module of the ANSYS 2021 software package and comparing the results obtained with the methodology presented in SP 292.1325800.2017 "Buildings and structures in tsunami-prone areas. Design rules". The studies presented in this article have shown that the nature of the propagation of hydrodynamic pressure when modeling wave rolling in ANSYS is similar to that presented in SP 292.1325800.2017: according to a triangular plot with maximum pressure at the bottom. But at the same time, the value of the maximum pressure on the joint venture is about 1.5 times greater than according to the calculation in ANSYS, which is explained by many different factors. But, despite this, modeling of the tsunami waves rolling on the construction site can be performed at the pre-project stage in order to assess the nature of the pressure distribution over the surface of the object, which will allow choosing the most suitable structural and space-planning solutions.

Investigating the impact of tsunami waves on gabion material-reinforced coastal structures: A numerical analysis

The tsunamis severely damaged several coastal structures in the past, including dykes, quay walls and breakwaters. The scouring of the foundation seabed has been identified as a key cause for the failure of many such structures during the tsunami. However, the scouring mechanisms involved with the response of these structures under tsunamis and possible methods to prevent such failures have not been well understood. Detailed numerical investigations are required to comprehend the dynamics underlying the foundation scouring of coastal structures. The complexity inherent in modelling a turbulent tsunami wave and its scouring effects on the seabed soil could be overcome by bridging multiple numerical analysis platforms. The present study thus attempts to quantify the scouring that occurred on the foundation soils of coastal structures through rigorous numerical simulations. Under the influence of the tsunami, significant scouring was seen on the seabed in the harbour side of the offshore structures, such as breakwaters. The depth of scouring depended on the overflowing velocity of tsunami waves and the impact stresses developed in the seabed. The addition of reinforcements has proven to be successful in lowering the scour depth by reducing the impact force of tsunami wave bore on the harbour side seabed. The efficiency of the suggested reinforcements has also been focused in the present study.

DEEP LEARNING TO PREDICT TSUNAMI HEIGHT AT THE SHORELINE USING OCEAN BOTTOM PRESSURE DATA

Real-time tsunami prediction is a required component of a tsunami warning system. Several advances have been made to improve prediction in the tsunami warning process, including precomputed databases and the assimilation of deep-ocean observations (DART buoys) into numerical modeling (Bernard and Titov, 2015). These improvements aim to accurately and quickly predict the time and height of the tsunami wave impact. Here, two deep learning models (DLM) are developed to predict the maximum tsunami height at a local/long shoreline from four time series observations of ocean bottom pressure data.

Storm or tsunamis: Boulder deposits on the rocky coasts of the Balearic Islands (Spain)

The origin of large imbricate boulders at the edge of coastal cliffs, by storm or tsunamis, is usually controversial. The Balearic Islands are a perfect place to elucidate this origin because the surrounding marine basins have low storm energy compared to oceans, and they are located 250 km N of the main tsunamigenic area of the Western Mediterranean. Thus, there have been recent and historical tsunamis affecting the Balearic Islands, especially in its southern and eastern parts. Tsunami simulations from submarine earthquakes on the North African coast predict the impact of tsunami waves on the Balearic Islands. Large coastal boulders of the Balearic Islands are located in the exact places numerical models predict they will be. Despite the fact that the height and energy of storm waves are much larger from the north and west, these boulders are located in the eastern and southern parts of the islands. Documentary sources confirm a very large tsunami affecting the southeast coast of Majorca in 1756, with a run-in up to 2 km and a run-up up to 45 m. Hydrodynamic equations applied to these boulders results in storm wave height values never recorded in 60 years. In February 2020, the highest storm wave ever recorded (14.33 m) was detected at Minorca buoy, related to storm Gloria. As predicted by hydrodynamic equations, none of the boulders studied moved significantly, and only three new boulders, located at sea level or at the cliff edge, were quarried. According to radiocarbon data and rate of growth of dissolution pans, the year of emplacement of boulders in the studied localities ranges between 1591 CE and 1894 CE. Thus, the distribution of the boulder sites along the islands, the historical record of a large tsunami, the run-up necessary for their placement, and the insignificant boulder movement produced by the highest storm recorded indicates that the cliff-top boulders of the Balearic Islands were quarried by North African tsunami waves.

Method for Calculating Extreme Loads on a Floating Object from the Direct Impact of Tsunami Waves Based on Experimental Studies

Method for Calculating Extreme Loads on a Floating Object from the Direct Impact of Tsunami Waves Based on Experimental Studies

Experimental Estimation of Loads on a Floating Object Exerted by the Direct Impact of Tsunami Waves

Experimental Estimation of Loads on a Floating Object Exerted by the Direct Impact of Tsunami Waves

Three-dimensional numerical simulations for mitigation of tsunami wave impact using intermittent sea dikes

Sea dikes are nowadays adopted for the protection of onshore infrastructures against devastating tsunami wave. For intermittent/discontinuous sea dikes, the flow fields are 3D in nature, making it necessary for three-dimensional model studies to analyze their effects on the peak tsunami impact force on a downstream structure. In this study, a numerical code based on a suitable turbulence closure model has been used to make simulations for trapezoidal sea dikes. The simulations have been performed for laboratory scale model. The simulation results for different dike length to gap ratios have shown that sea dikes with 25% gaps will be adequate as the peak impact force on an onshore building is reduced by 36%, while a continuous sea dike can reduce the peak impact force approximately by 40%. A composite dike wherein a 50% length of the larger trapezoidal cross-section is alternated with a smaller rectangular section is capable of reducing peak tsunami impact force by approximately 32%. Two staggered rows of intermittent dikes give better protection than a single row of intermittent dike. However, the protection is marginally lesser than that given by a single continuous dike.

Megatsunamis and microbial life on early Mars

AbstractIt is currently believed that early Mars had a vast and shallow ocean, and microbial life may have formed in it, albeit for a short geological time. The geological evidence indicates that during the existence of this ocean, large collisions occurred on the surface of Mars, which led to the formation of megatsunamis in its palaeo-ocean. Previous research has reported on the effects of tsunami waves on microbial ecosystems in the Earth's oceans. This work indicates that tsunami waves can cause changes in the physico-chemical properties of seawater, as well as tsunami-affected land soils. These factors can certainly affect microbial life. Other researchers have shown that there are large microbial communities of marine prokaryotes (bacteria and archaea) in tsunami-induced sediments. These results led us to investigate the impact of tsunami waves on the proposed microbial life in the ancient Martian ocean, and its role in the preservation or non-preservation of Martian microbial life as a fossil signature.

Submarine Landslides in the West Continental Slope of the South China Sea and Their Tsunamigenic Potential

The 109 meridian fault is located in the west of the South China Sea (SCS) connecting to the offshore Red River Shear Zone. Seismic data from the central Vietnamese shelf indicates that many submarine landslides were developed along the steep continental slope in this offshore region. Here, we analyze the potential for such landslides to trigger damaging tsunamis based on the local geological background and sedimentary environment. We assess their tsunamigenic potential along the coast of Southern Central Vietnam (SCV). We point out that the evolutionary processes of the 109° meridian fault: striking-subsidence of the adjacent basin, combined with the high sediment input from numerous montane rivers of the hinterland generate conditions that likely favor the development of submarine landslides along the well-defined and steep continental slope near SCV. To estimate the impact of tsunami waves on the SCV coastline, we conducted a pilot study using two numerical models: NHWAVE and FUNWAVE-TVD to model 4 representative landslides with volumes ranging between 1.3 and 14 km3 and water depth of 300–1000 m. The submarine landslides were treated as rigid slump and deformable slide corresponding to two different sedimentary environments. Our results show that the tsunami waves generated by rigid slump can reach up to 20 m height in the landslide source area and ∼5 m when arriving at the closest coastline. Tsunami waves could arrive at the central Vietnam coast within 30 min in eight scenarios. Our initial results also suggest that seafloor topography, i.e., waveguide effects of ocean ridges, shelf resonance and the potential bay resonance cause significant variability in potential run-up. We note that ocean ridges located in the deep basin of the SCS focus the tsunami energy propagating towards the northwest coast of Luzon Island, Philippines where tsunami wave heights of ∼2.3 m wave height are modeled. These findings underscore the importance of tsunami hazard assessments that account for both earthquake generated and earthquake triggered tsunamis. Our work also highlights a continued need to examine tsunami sources in the region as mitigation and preparedness for the socio-economically important and heavily populated coastlines of the SCS is reliant on a detailed understanding of the hazard.

Seismic Performance of Offshore Piers under Wave Impact and Chloride Ion Corrosion Environment

Offshore bridges may suffer from chloride ion corrosion, tsunami wave impact, and earthquake. However, the coupling effects of multiple factors have not been fully considered. This paper studied multiple degradation effects on the seismic performance of offshore piers considering tsunami wave impact, chloride ion corrosion, and their interaction. Firstly, through the scale model test of tsunami wave flume, the wave force of box girder structures and piers under different tsunami wave conditions is measured. Then, according to the corrosion characteristics of coastal chloride salts on reinforced concrete bridge piers, the corrosion parameters is selected by Latin hypercube sampling, and the influence of corrosion expansion and cracking of bridge pier cover on the chloride ion corrosion process is considered to modify the degradation model of corroded reinforced concrete materials. Finally, the wave load measured by the test is converted by the similarity criterion of the fluid mechanic test and loaded into the ABAQUS full-bridge model, and the pier after the tsunami wave is evaluated by the pushover analysis. The bearing capacity and lateral stiffness of the corroded pier before and after different tsunami waves are compared. The results show that the lateral bearing capacity and stiffness of bridge piers are, respectively, decreased by 27.6% and 6.2% after 30 years of service. Without corrosion, the lateral bearing capacity and stiffness of piers were, respectively, reduced by 11.45% and 10.6% after HXB-5 wave impact. After 30 years of service, the lateral bearing capacity and stiffness of bridge piers are, respectively, reduced by 41.8% and 22.5% under the combined action of corrosion and HXB-5 wave impact. It is found that the coupling effects of multiple degradation factors were more significant than the simple superposition ones. Therefore, the coupling effect of multiple factors should be considered in practical engineering.

Tsunami wave impact assessment for residences in Pattinapakkam, Chennai coast using DualSPHysics

The method of Smoothed Particle Hydrodynamics (SPH) is getting main-stream starting late to model non-linear problems of coastal engineering applications. This work has been conveyed to investigate the appropriateness of DualSPHysics to model Tsunami in disaster management program in predicting the wave pressure, velocity and wave height. A numerical model has been set up for assessing the wave loads on structures on the Pattinapakkam area along Chennai coast. The region selected for the study is located at a distance of 42 m from the shoreline which is more inclined to wave attack during Tsunami. For simplification, the area of the region considered in the model is 917 m2. The digital elevation model (DEM) output of Pattinapakkam has been used to reproduce the real coastal profile of the region. The tsunami waves considered in the SPH method is the solitary waves. The weakly compressible SPH approach has been used in this simulation because, in light of the fact that, the fluids are weakly compressible in nature. The results including the wave pressure, velocity and wave height parameters are presented and wave pressure acting on few structures are moreover given. ABAQUS model simulation has additionally been used to study the pattern of deformation of the structures in the domain. The study determined that DualSPHysics was able to model highly non-linear problems with practically no deformations. The main disadvantage is that it requires computationally efficient machine in modeling real time problems as the real model includes couple of million particles in simulation. It recommends that DualSPHysics goes about as a prevalent tool in the disaster management program.

Effect of tsunami load induced by earthquake at Manila Trench on transmission tower

The Manila Trench subduction zone is an active convergent plate margin between the South China Sea and northern Philippines. This strongly indicates a high probability for larger earthquakes that could potentially trigger a tsunami in the future and anticipated to affect neighboring countries such as Malaysia which has power plants near the coastal areas. The potential disastrous impact of tsunami waves on a power plant causes loss of lives, damage to assets, and loss of electricity for the coastal communities similar to year 2011 Tohoku tsunami in Japan. Therefore, application of shallow water equation (SWE) in tsunami modelling namely generation and propagation phase and nonlinear shallow water equation (NSWE) for run-up and inundation phase of a tsunami event are pertinent in simulating various scenarios of tsunami. Results from tsunami simulation is used as tsunami lateral load. Linear Static Analysis is then utilized to analyze stability of 275-kV transmission tower.

Globally Scattered 2011 Tohoku Tsunami Waves From a Seafloor Sensor Array in the Northeast Pacific Ocean

AbstractModeling of tsunami wave propagation for forecasting focuses on the arrival time and amplitude of the earliest tsunami waves reaching coastlines. The complex later tsunami wavefield, in which scattering is predominant, poses additional hazards due to possible constructive interference of coherent packets of wave energy. However, almost no data sets exist to characterize the geographical sources and temporal evolution of the scattered waves. Here we show how recordings of the 2011 Tohoku tsunami by an array of pressure gauge sensors in the northeastern Pacific Ocean reveal coherent waves that are produced by scattering from distant coastlines including South America and Antarctica, as well as multiple seafloor fracture zones, ridges, and island chains. Multiple signal classification analysis and backward propagation ray tracing provide tight constraints on the origin of each scattered phase and resolve simultaneous wave arrivals from different scatterers. Incoming waves from constant back azimuths occur over time durations of several hours, revealing the time persistence of specific geographical scatterers. The results can advance numerical predictions of tsunami wave impact because they provide direct evidence for the necessity of incorporating both local and distant bathymetry over a range of length scales and for long time durations, to account for the azimuthal dependence of scatterer strength.

Spectral wave modeling of tsunami waves in Pohang New Harbor (South Korea) and Paradip Port (India)

A coupled numerical model is developed based on the spectral element method (SEM) and boundary element method (BEM) to predict the characteristics of tsunami wave response on Pohang New Harbor (PNH), South Korea, and Paradip Port, India. The current numerical model is developed to analyze the impacts on the coastal region with slowly varying bathymetry under the resonance conditions. In this method, the boundary integral equation of each boundary segment is discretized into the spectral elements using the Chebyshev’s polynomial, and the corresponding boundary integrals are transformed using the Jacobian of transformation. This leads to a highly accurate depiction of the boundary edges or corners of the complex domain. Convergence and error analyses are conducted on the rectangular port using the BEM and the present method, which shows that the later approach enhances the overall numerical accuracy of the model. The simulation results for normal day wave (ordinary wave propagating in the ocean under normal conditions) and tsunami waves are validated with previous studies and measurement data at Pohang New Harbor (PNH), South Korea. In addition, the calculated spectral density for tsunami waves at PNH is also compared with the Hokkaido tsunami (reported on July 12, 1993) data at tide gauge record station in Pohang. The amplification factor is determined for normal day wave and tsunami waves at key locations inside the PNH and Paradip Port for different directional incident waves. Further, the spectral density is also estimated at the same locations with respect to the wave period to understand the consequences of tsunami waves on the coastal ports. Therefore, the coupled numerical model is an efficient tool to predict tsunami wave impact on a realistic port. The causes and countermeasure are suggested to reduce the risk of normal day waves and tsunami waves.