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The 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. [ABSTRACT FROM AUTHOR]

Conditions for the applicability of the dispersionless theory of long waves for reproducing dispersive tsunami waves are analyzed. The dispersive destruction distance is proposed for use as a quantitative criterion, a value that is uniquely determined by the wavelength that dominates in the spectrum of the initial elevation of the water surface in the tsunami source and by correction factor The physical meaning of value is the fraction of the wavelength by which the dispersive wave packet lags behind the long-wave front when propagating over a distance equal to the dispersive destruction distance. Using the model residual displacement of the bottom surface, the geometrical parameters of which vary randomly, under the assumption of the instantaneous generation of waves and taking into account the smoothing effect of the water layer, the Monte Carlo method establishes a relationship between the accuracy of wave reproduction by the dispersionless model and the value Using the coefficient scale, criteria previously proposed by other authors are ranked. [ABSTRACT FROM AUTHOR]

SUMMARY: The 15 January 2022 eruption of the Hunga–Tunga volcano generated a Lamb pressure wave propagating all over the globe and triggering a tsunami throughout the planet. A first atmospheric wave arrived 16 hr after the eruption on the French Mediterranean coasts and propagated southward. A second one originating from Africa was observed 4 hr later with an attenuated amplitude. The first wave can be roughly defined either by a N wave or a sinusoid signal with a period close to 50 min and an amplitude of 130 Pa. In the Mediterranean Sea, the tsunami was recorded by almost all standard coastal tide gauges or pressure gauges. The French tide gauge stations recorded water waves with amplitudes ranging from a few centimetres to 10 cm and with periods ranging from 10 min to 1 hr. Numerical simulation of the tsunami is performed by the operational code Taitoko for different atmospheric sources. Non-linear shallow water equations are solved by a finite-difference method, using the nested multigrid approach. The tsunami is generated by calculating analytically the atmospheric pressure gradient in the momentum equations. Comparisons of time-series between numerical solutions and records are satisfactory for most tide-gauges along the French Mediterranean coast. Sensitivity analysis on the atmospheric source and on the resolution is performed. For most tide-gauge stations, numerical results show that the wave forms depend first on local resonance phenomena. [ABSTRACT FROM AUTHOR]

A model for tsunamis propagation is derived by coupling a weakly compressible liquid layer, standing for the ocean, to a viscoelastic solid layer of constant depth, representing the upper layer of the Earth. Below this layer, the Earth is assumed to be perfectly rigid. The resulting equations are averaged over the depth of the water layer for the liquid part and are integrated over the thickness of the solid layer for the solid part. The obtained system of equations is hyperbolic and admits an exact equation of energy conservation. The model is dispersive and includes an elastic branch, an acoustic branch and a gravity branch. The elasticity of the solid layer entails: (1) a reverse dispersion effect i.e. the phase velocity of the gravity branch decreases for small wave numbers if the wave number decreases; (2) an arrival time delay of the tsunami and (3) a leading negative phase i.e. a negative water elevation before the arrival of the main wave. All these effects are absent if the sea floor is assumed to be perfectly rigid. The arrival time delay due to elasticity comes in addition to the delay due to seawater compressibility. These effects are in agreement with previous works on tsunamis propagation. This preliminary model is a promising alternative approach for tsunamis propagation due to its ability to capture the main physical effects with a relatively simple mathematical structure of equations, which is easy to solve numerically. [ABSTRACT FROM AUTHOR]

Tsunami buoy, linked to satellite, is commonly used as a tsunami early warning system but has been discovered to have several drawbacks such as the need for approximately 5 minutes to issue an early warning for a tsunami after detecting the initial wave as well as its fragility. It was also reported that the twenty-two buoys placed in the Indonesian seas from 2012 to 2018 were damaged and missing. Therefore, this study proposes a new method for tsunami early warning by integrating ship-to-ship maritime wireless communication. It is important to note that vessels or fishing boats with over 30 GT have the ability to travel more than 100 nmi (approximately 180 km) from the shoreline and can be equipped with point-to-multipoint VHF radio communication. Meanwhile, smaller boats on the fishing ground located approximately 2-5 km from the shore can use a WiFi network to communicate like a wireless mesh while the existing terrestrial network can be used for the ship-to-shore communication between boats and land stations. This system is expected to provide significant benefits for a fishing town such as Pangandaran, West Java, Indonesia which is directly facing Java Megathrust in the Indian Ocean. Therefore, a tsunami numerical simulation was conducted in this study using Shallow Water Equation which involved a hypothetical tsunami simulated from the possible fault source which is approximately 250 km from the source. Moreover, the vessel’s location was assumed to be in line with the fishing ground while the arrival time of the tsunami was estimated from the model to be 22.5 minutes and compared to the relay time of the proposed system which was approximately 5.4 seconds. This is faster in terms of delay than the existing system which relays information through satellite at approximately 5 minutes in an ideal condition and also has the ability to reduce the need for tsunami buoys.

Tsunami coastal hazard is modeled along the US East Coast (USEC), at a coarse regional (450 m) resolution, from coseismic sources located in the Açores Convergence Zone (ACZ) and the Puerto Rico Trench (PRT)/Caribbean Arc areas. While earlier work only considered probable maximum tsunamis, here we parameterize and simulate 18 coseismic sources, with magnitude M8-9 and return periods ∼ 70–2000 year, using seismo-tectonic and historical data. The largest sources in the ACZ are repeats of the 1755 M8.6-9 Lisbon earthquake and tsunami; other sources are hypothetical. In the ACZ, due to the limited data on faults, each source is parameterized with a single fault plane, while in the PRT, coseismic sources are parameterized based on fault segmentation established during a 2019 USGS workshop of experts, using 10–26 SIFT subfault planes (Gica et al. in NOAA Tech. Memo., OAR PMEL-139, 2008). Tsunamis are simulated for each source using the fully nonlinear and dispersive model FUNWAVE-TVD, in two levels of nested grids. At the considered scales, dispersion is shown to affect tsunami propagation. Coastal hazard is quantified by four metrics computed at many save points (∼ 20–30 thousand) defined along the 5-m isobath (due to the coarse resolution), i.e., maximum (1) surface elevation, (2) current, (3) momentum force; and (4) travel time, representing flooding, navigation, structural, and evacuation hazards. Overall, the first three metrics are larger, the larger the source magnitude, and their alongshore variation shows similar patterns of higher/lower values, due to the shelf bathymetric control (refraction). The fourth metric mostly differs between sources from each area, but less so among sources from the same area; its inverse quantifies evacuation hazard. A 1–5 score is given to results for each metric, based on five intensity classes representing low, medium low, medium, high, and highest tsunami hazard. A novel tsunami intensity index is computed as a weighted average of these scores, allowing both a comparison among sources and a quantification of tsunami hazard as a function of their estimated return periods. In the most impacted areas of the USEC, the highest tsunami hazard in the 250–500-year return period range is commensurate with that posed by 100-year category 3–5 tropical cyclones, taking into account the larger current velocities and forces caused by tsunami waves. Results of this work could serve as a basis for a future regional Probabilistic Tsunami Hazard Analysis for the USEC, considering additional source types such as underwater landslides, volcanic flank collapse, and meteotsunamis, that were studied elsewhere. [ABSTRACT FROM AUTHOR]

This paper presents the new version of the operational code used at the Tsunami Warning Centers in French Polynesia and in mainland France. This nested multigrid code solves either the nonlinear shallow water or the weakly nonlinear Boussinesq equations in a spherical or Cartesian coordinates system. The objective is to simulate the propagation of tsunamis both in the context of tsunami early warning and in the context of research. The originality of this code is to simulate the tsunami propagation through a series of nested grids in which the numerical scheme is specified by the user. Three standard finite-difference methods and two finite volume schemes are available to take into account the dispersive nature of waves or to capture flow discontinuities. The performance of the five numerical schemes has been assessed through idealized 1D and 2D test cases. The convergence rate with grid refinement is evaluated for three of these tests. Diffusion and dispersion of the five schemes are evaluated through the 1D far-field propagation in a channel of constant depth. Finally, two-dimensional simulations of the 2011 Japanese tsunami are performed considering a homogeneous tectonic source. Coastal inundation is simulated in the bay of Kamaishi where run-up heights reached 10 m. The ability of the five schemes to propagate trans-Pacific tsunamis is evaluated through comparisons of time series between simulations and observations at DART buoys. In the context of tsunami early warning, numerical results show that standard finite-difference methods reproduce most of the observed time gauges and that numerical errors associated to these schemes are acceptable. • Tsunami simulation is performed both in a research and an operational context. • Three finite-difference methods and two finite volume schemes are presented. • The five numerical schemes are assessed through 1D and 2D numerical experiments. • The trans-Pacific propagation of the 2011 Japanese tsunami is simulated. • Standard finite-difference methods are acceptable in an operational context. [ABSTRACT FROM AUTHOR]

A tsunami is a significant coastal hazard that causes destructive damage to coastal cities in the world. Besides, tsunamis, generated on the west coast of Japan, damaged coastal cities on the east coast of Korea in 1983 and 1993. In recent years, there has been increasing interest in the potential tsunami zone near the west coast of Japan. Therefore, it is important to have tsunami observation instruments in proper locations for tsunami detection and warning aspect. This study proposes the optimal region for offshore tsunami observation instrument deployment under the limited condition that the tsunami source in out of the territorial sea by investigating areas with the highest tsunami detection probability along with maximum evacuation time and bottom slope. Using the Cornell Multi-grid Coupled Tsunami (COMCOT) numerical model and a probabilistic approach, this study suggests the optimal region for offshore tsunami detection instrument deployment to be the northeast area of Ulleung-do Island in the eastern sea of Korea. [ABSTRACT FROM AUTHOR]

Tsunami modelling is widely used to estimate the potential impacts of tsunamis. Models require a tide input, which can be either static, representing a specific tide level, such as Highest Astronomic Tide or dynamic, which represents a moving tide level. Although commonly used, static tide inputs do not account for tsunami–tide interactions, which are known to be non-linear and more significant in estuaries when compared to the open coast. To demonstrate the differences between tsunami models using static or dynamic tide inputs, a series of models were carried out for two New South Wales estuaries, Sydney harbour and port hacking. Model boundary conditions phased a MW 9.0 Puysegur source tsunami with multiple tide scenarios. Fourteen distinct scenarios with dynamic tides were created by phasing the largest tsunami wave peak at regular intervals across the tidal range. For comparison, static tide models were run using equivalent tide levels. The situations where static tide models provide results comparable or more conservative than dynamic tide models are for the first 1–2 h after tsunami arrival, at high tides, and when compared to dynamic falling tides at the same tide level. Differences are most apparent upriver of geomorphological constrictions. The effects of geomorphological constrictions were further examined using idealised model setups with a constriction variable. Results show that constrictions affect downriver maximum water levels, tsunami wave heights, upriver water accumulation and inundation maxima and distributions. These results have implications for estuaries vulnerable to erosion at constriction sites during a tsunami event. [ABSTRACT FROM AUTHOR]

In this paper, the kinematics of the tsunami wave ray and the wave front in the area, where the depth increases proportional to the squared distance to the straight shoreline, is studied. The exact analytical solution for the wave-ray trajectory above the parabolic bottom topography has been derived. This solution gives the possibility to determine in the ray approximation the tsunami wave heights in an area with the parabolic bottom topography. The distribution of the wave-height maxima in the area with such a bathymetry is compared to that obtained with a shallow-water model. All the exact solutions obtained can be used for testing numerical algorithms.

Previous studies have reported seismic observations of tsunami recorded at island broadband stations. Coastal loading by the tsunami can explain them. For further quantification, we model tsunami propagation assuming an axisymmetric structure: a conical island with a flat ocean floor. The total tsunami wavefield can be represented by superposition between an incident tsunami wave and the scattering. The ground deformation due to the total tsunami wavefield at the center is calculated using static Green's functions for elastic half‐space with a first‐order correction for bathymetry. By fitting the modeled displacement to observed seismic data, we can infer the incident tsunami wave, which can be interpreted as the virtual tsunami amplitude without the conical island. First, we apply this new method to three components of seismic data at a volcano island, Aogashima, for the 2015 Torishima‐Oki tsunami earthquake. The estimated tsunami amplitude from the vertical component is consistent with the offshore array observation of absolute pressure gauges close to the island (1.5–20 mHz). The estimated incident azimuth from the three components is also consistent with ray theory. Second, we apply this method to seismic data at four island broadband stations in the Indian ocean for the 2010 Mentawai tsunami earthquake in Indonesia. Despite the limited observed frequency range from 0.5–2.0 mHz, the amplitudes and incident azimuths are consistent with past studies. These observations can complement offshore tsunami observations. Moreover, this method is applicable not only for a tsunami but also for background ocean infragravity wave activity. Key Points: For quantification of seismic observation of tsunami, we evaluate scattering of an incident tsunami for an axisymmetric structureGround deformation due to the tsunami loading is calculated using static Green's functionsBy fitting the modeled displacement to observed seismic data, the incident tsunami is inferred from the seismic observation [ABSTRACT FROM AUTHOR]

This study demonstrates the skills of D-FLOW Flexible Mesh (FM) and SFINCS (Super-Fast INundation of CoastS) in combination with the Delft Dashboard Tsunami Toolbox to numerically simulate tsunami offshore propagation and inundation based on the example of the 2011 Tōhoku tsunami in Japan. Caused by a megathrust earthquake, this is one of the most severe tsunami events in recent history, resulting in vast inundation and devastation of the Japanese coast. The comparison of the simulated with the measured offshore water levels at four DART buoys located in the north-western Pacific Ocean shows that especially the FM but also the SFINCS model accurately reproduce the observed tsunami propagation. The inundation observed at the Sendai coast is well reproduced by both models. All in all, the model outcomes are consistent with the findings gained in earlier simulation studies. Depending on the specific needs of future tsunami simulations, different possibilities for the application of both models are conceivable: (i) the exclusive use of FM to achieve high accuracy of the tsunami offshore propagation, with the option to use an all-in-one model domain (no nesting required) and to add tsunami sediment dynamics, (ii) the combined use of FM for the accurate simulation of the tsunami propagation and of SFINCS for the accurate and time efficient simulation of the onshore inundation and (iii) the exclusive use of SFINCS to get a reliable picture of the tsunami propagation and accurate results for the onshore inundation within seconds of computational time. This manuscript demonstrates the suitability of FM and SFINCS for the rapid and reliable assessment of tsunami propagation and inundation and discusses use cases of the three model combinations that form an important base for tsunami risk management.

The present study examines the historical earthquakes and tsunamis of 21 July 365 and of 9 February 1948 in the Eastern Mediterranean Sea. Numerical simulations were performed for the tsunamis generated by underwater seismic sources in frames of the keyboard model, as well as for their propagation in the Mediterranean Sea basin. Similarly examined were three different types of seismic sources at the same localization near the Island of Crete for the earthquake of 21 July 365, and of two different types of seismic sources for the earthquake of 9 February 1948 near the Island of Karpathos. For each scenario, the tsunami wave field characteristics from the earthquake source to coastal zones in Mediterranean Sea’s basin were obtained and histograms were constructed showing the distribution of maximum tsunami wave heights, along a 5-m isobath. Comparison of tsunami wave characteristics for all the above mentioned scenarios, demonstrates that underwater earthquakes with magnitude M > 7 in the Eastern Mediterranean Sea basin, can generate waves with coastal runup up to 9 m.

The study focuses on the sensitivity of frequency dispersion effects to the form of initial surface elevation of seismic tsunami source. We vary such parameters of the source as rupture depth, dip-angle and rake-angle. Some variations in magnitude and strike angle are considered. The fully nonlinear dispersive model on a rotating sphere is used for wave propagation simulations. The main feature of the algorithm is the splitting of initial system on two subproblems of elliptic and hyperbolic type, which allows implementation of well-suitable numerical methods for them. The dispersive effects are estimated through differences between computations with the dispersive and nondispersive models. We consider an idealized test with a constant depth, a model basin for near-field tsunami simulations and a realistic scenario. Our computations show that the dispersion effects are strongly sensitive to the rupture depth and the dip-angle variations. Waves generated by sources with lager magnitude may be even more affected by dispersion.

A tsunami is a significant coastal hazard that causes destructive damage to coastal cities in the world. Besides, tsunamis, generated on the west coast of Japan, damaged coastal cities on the east coast of Korea in 1983 and 1993. In recent years, there has been increasing interest in the potential tsunami zone near the west coast of Japan. Therefore, it is important to have tsunami observation instruments in proper locations for tsunami detection and warning aspect. This study proposes the optimal region for offshore tsunami observation instrument deployment under the limited condition that the tsunami source in out of the territorial sea by investigating areas with the highest tsunami detection probability along with maximum evacuation time and bottom slope. Using the Cornell Multi-grid Coupled Tsunami (COMCOT) numerical model and a probabilistic approach, this study suggests the optimal region for offshore tsunami detection instrument deployment to be the northeast area of Ulleung-do Island in the eastern sea of Korea.

Some boundary conditions used to numerically simulate tsunami generation and propagation are studied. Special attention is given to generating boundary conditions thatmake it possible to simulate tsunami waves with desired characteristics (amplitude, time period and, in general, waveform). Since the water flow velocity in a propagating tsunami wave is uniquely defined by its height and ocean depth, one can simulate a wave propagating from the boundary into the simulation area. This can be done by specifying the wave height and water flow velocity on the boundary. This method is used to numerically simulate the propagation of a tsunami from the source to the coast on a sequence of refined grids. In this numerical experiment the wave parameters are transferred from the larger area to the subarea via boundary conditions. This method can also generate a wave that has certain characteristics on a specified line. [ABSTRACT FROM AUTHOR]

Ray tracing, which has been widely used for seismic waves, was also applied to tsunamis to examine the bathymetry effects during propagation, but it was limited to linear shallow-water waves. Green’s law, which is based on the conservation of energy flux, has been used to estimate tsunami amplitude on ray paths. In this study, we first propose a new ray tracing method extended to dispersive tsunamis. By using an iterative algorithm to map two-dimensional tsunami velocity fields at different frequencies, ray paths at each frequency can be traced. We then show that Green’s law is valid only outside the source region and that extension of Green’s law is needed for source amplitude estimation. As an application example, we analyzed tsunami waves generated by an earthquake that occurred at a submarine volcano, Smith Caldera, near Torishima, Japan, in 2015. The ray-tracing results reveal that the ray paths are very dependent on its frequency, particularly at deep oceans. The validity of our frequency-dependent ray tracing is confirmed by the comparison of arrival angles and travel times with those of observed tsunami waveforms at an array of ocean bottom pressure gauges. The tsunami amplitude at the source is nearly twice or more of that just outside the source estimated from the array tsunami data by Green’s law. [ABSTRACT FROM AUTHOR]

In the last years several numerical codes have been developed to analyse tsunami waves. Most of these codes use a finite difference numerical approach giving good results for tsunami wave propagation, but with limitations in modelling inundation processes. The HyFlux2 model has been developed to simulate inundation scenario due to dam break, flash flood and tsunami-wave run-up. The model solves the conservative form of the two-dimensional shallow water equations using a finite volume method. The implementation of a shoreline-tracking method provides reliable results. HyFlux2 robustness has been tested using several tsunami events. The main aim of this study is code validation by means of comparing different code results with available measurements. Another objective of the study is to evaluate how the different fault models could generate different results that should be considered for coastal planning. Several simulations have been performed to compare HyFlux2 code with SWAN-JRC code and the TUNAMI-N2. HyFlux2 has been validated taking advantage of the extensive seismic, geodetic measurements and post-tsunami field surveys performed after the Nias March 28th tsunami. Although more detailed shallow bathymetry is needed to assess the inundation, diverse results in the wave heights have been revealed when comparing the different fault mechanism. Many challenges still exist for tsunami researchers especially when concern to early warning systems as shown in this Nias March 28th tsunami.

Abstract: This study aims at understanding the role of tidal level, speed, and direction in tsunami propagation in highly energetic tidal channels. The main goal is to comprehend whether tide‐tsunami interactions enhance/reduce elevation, currents speeds, and arrival times, when compared to pure tsunami models and to simulations in which tides and tsunamis are linearly superimposed. We designed various numerical experiments to compute the tsunami propagation along Canal Chacao, a highly energetic channel in the Chilean Patagonia lying on a subduction margin prone to megathrust earthquakes. Three modeling approaches were implemented under the same seismic scenario: a tsunami model with a constant tide level, a series of six composite models in which independent tide and tsunami simulations are linearly superimposed, and a series of six tide‐tsunami nonlinear interaction models (full models). We found that hydrodynamic patterns differ significantly among approaches, being the composite and full models sensitive to both the tidal phase at which the tsunami is triggered and the local depth of the channel. When compared to full models, composite models adequately predicted the maximum surface elevation, but largely overestimated currents. The amplitude and arrival time of the tsunami‐leading wave computed with the full model was found to be strongly dependent on the direction of the tidal current and less responsive to the tide level and the tidal current speed. These outcomes emphasize the importance of addressing more carefully the interactions of tides and tsunamis on hazard assessment studies. [ABSTRACT FROM AUTHOR]

In this paper, the kinematics of the tsunami wave ray and the wave front in the area, where the depth increases proportional to the squared distance to the straight shoreline, is studied. The exact analytical solution for the wave-ray trajectory above the parabolic bottom topography has been derived. This solution gives the possibility to determine in the ray approximation the tsunami wave heights in an area with the parabolic bottom topography. The distribution of the wave-height maxima in the area with such a bathymetry is compared to that obtained with a shallow-water model. All the exact solutions obtained can be used for testing numerical algorithms. [ABSTRACT FROM AUTHOR]

We perform numerical simulations to assess how coastal tsunami hazard from submarine mass failures (SMFs) is affected by slide kinematics and rheology. Two types of two-layer SMF tsunami generation models are used, in which the bottom (slide) layer is depth-integrated and represented by either a dense Newtonian fluid or a granular flow, in which inter-granular stresses are governed by Coulomb friction (Savage and Hutter model). In both cases, the upper (water) layer flow is simulated with the non-hydrostatic 3D σ-layer model NHWAVE. Both models are validated by simulating laboratory experiments for SMFs made of glass beads moving down a steep plane slope. In those, we assess the convergence of results (i.e., SMF motion and surface wave generation) with model parameters and their sensitivity to slide parameters (i.e., viscosity, bottom friction, and initial submergence). The historical Currituck SMF is simulated with the viscous slide model, to estimate relevant parameters for simulating tsunami generation from a possible SMF sited near the Hudson River Canyon. Compared to a rigid slump, we find that deforming SMFs of various rheology, despite having a slightly larger initial acceleration, generate a smaller tsunami due to their spreading and thinning out during motion, which gradually makes them less tsunamigenic; the latter behavior is controlled by slide rheology. Coastal tsunami hazard is finally assessed by performing tsunami simulations with the Boussinesq long wave model FUNWAVE-TVD, initialized by SMF tsunami sources, in nested grids of increasing resolution. While initial tsunami elevations are very large (up to 25 m for the rigid slump), nearshore tsunami elevations are significantly reduced in all cases (to a maximum of 6.5 m). However, at most nearshore locations, surface elevations obtained assuming a rigid slump are up to a factor of 2 larger than those obtained for deforming slides. We conclude that modeling SMFs as rigid slumps provides a conservative estimate of coastal tsunami hazard while using a more realistic rheology, in general, reduces coastal tsunami impact. [ABSTRACT FROM AUTHOR]

The December 26, 2004 Sumatra earthquake’s epicenter was 163 kms away from Great Nicobar, the southern most island from the archipelago and hence it was strongly felt in the entire Andaman & Nicobar group of islands including Car Nicobar. 3400 people have lost their lives and most of the vital infrastructure were completely destroyed. The presents study aims to understand the vulnerability of the Car Nicobar coast to tsunami hazard from varied sources by using numerical model of tsunami propagation and run-up and compare it with the field data on inundation collected immediately after the tsunami using real time kinematic GPS. A tsunami vulnerability database has been builtup by modelling the past earth quakes recorded in this region. Elevation data collected using Airborne Laser Terrain Mapper (ALTM) was used to generate the inundation scenarios. A GIS database on the tsunami vulnerability of Car Nicobar to tsunami hazard is generated which would be immense use in mitigation and planning.

There are many methods for computing tsunami kinematics directly and inversely. The direct detection of waves in the deep ocean makes it possible to establish tsunami source characteristics and origin. Thus, accuracy of computational methods is very important in obtaining reliable results. In a non-homogeneous medium where tsunami wave propagation velocity varies, it is not very easy to determine a wave-ray that connects two given points along a path. The present study proposes modification in the methodology of determining tsunami travel-times and of wave-ray paths. An approximate ray trace path can be developed from a source origin point to any other point on a computational grid by solving directly the problem - and thus obtain the tsunami travel- times. The initial ray approximation can be optimized with the use of an algorithm that calculates all potential variations and applies corrections to travel-time values. Such an algorithm was tested in an area with model bathymetry and compared with a non-optimized method. The latter exceeded the optimized method by one minute of travel-time for every hour of tsunami propagation time.

The sea levels recorded in the wake of Indian Ocean Tsunami of December 2004 and of the Kuril Island Tsunami of November 2006 show strong tsunami signal enhancement of the late arriving secondary waves. Using these tsunami eventswe demonstrate thatsudden changes caused by higher energy pulses in the intermittent tsunami wave trains can be assessed by energy fluxes. Therefore, to delineate the regions of tsunami wave amplification and travel time we propose to use energy flux.A series of numerical experimentsdefinedinexplicitwaythe bathymetric features which scatter tsunami signal towards ports, like Crescent City. Identification of the distant bathymetric featureswas achievable sincethe energy fluxvectordelineatedthe energy pathways that coupled distant bathymetric features to portslocated thousands of kilometers apart. Calculations of the energy flux vector involves simple formulas based on two components of velocity and sea level. The maximum of the energy flux (which has no directional properties) can be evaluated from the sea level amplitude, hence both observed and computed sea level can be used for this purpose. The main task of this paper is to suggest that tsunami warning and prediction services should use numerical-hydrodynamical models with wider scope of physical processes by incorporating the energy balance equation into presently used tools.

In this paper, the kinematics of tsunami wave rays and wavefronts propagating over an uneven bottom is considered. Formulas to determine the wave height along a ray tube are obtained. An exact analytical solution for the trajectory of a wave ray over a parabolic bottom is derived. In the wave-ray approximation, this solution makes it possible to analytically determine the heights of tsunami waves over an area with a sloping bottom. The distribution of wave-height maxima over an area with a parabolic bottom is compared with that obtained by numerical computation with a shallow-water model. [ABSTRACT FROM AUTHOR]

The seismic crisis that hit Calabria (South Italy) since the beginning of 1783, lasted 3 years with strong earthquakes concentrated in the first 2 months, causing many fatalities and great destruction, as reported by several detailed historical reports. Following an earthquake that occurred on February 6, 1783, a mass with volume of about 6 Mm detached from the flank of Mount Pacì and collapsed into the sea. In 1 min, huge waves attacked the nearby village of Scilla and killed most of the people that had gathered in the wide shore named Marina Grande to escape from seismic danger. More than 1500 people died due to the tsunami, many buildings were destroyed. In the paper, such catastrophic event is studied by means of numerical models. First we reconstruct the initial sliding mass and compute its motion through a Lagrangian model; then, we simulate the tsunami generation, propagation and flooding on the coast of Scilla by means of a nonlinear shallow-water equations model. The results of the simulation are compared against the detailed description of the tsunami effects available from several historical accounts and are found to be in a very satisfactory agreement with the 6-8 m inundation height reported in the Marina Grande beach. [ABSTRACT FROM AUTHOR]

The present study examines the historical earthquakes and tsunamis of 21 July 365 and of 9 February 1948 in the Eastern Mediterranean Sea. Numerical simulations were performed for the tsunamis generated by underwater seismic sources in frames of the keyboard model, as well as for their propagation in the Mediterranean Sea basin. Similarly examined were three different types of seismic sources at the same localization near the Island of Crete for the earthquake of 21 July 365, and of two different types of seismic sources for the earthquake of 9 February 1948 near the Island of Karpathos. For each scenario, the tsunami wave field characteristics from the earthquake source to coastal zones in Mediterranean Sea's basin were obtained and histograms were constructed showing the distribution of maximum tsunami wave heights, along a 5-m isobath. Comparison of tsunami wave characteristics for all the above mentioned scenarios, demonstrates that underwater earthquakes with magnitude M > 7 in the Eastern Mediterranean Sea basin, can generate waves with coastal runup up to 9 m. [ABSTRACT FROM AUTHOR]

Since the devastating earthquake of 2010 in Haiti, significant efforts have been devoted to estimating future seismic and tsunami hazard in Hispaniola. In 2013, following a workshop of experts, UNESCO commissioned an initial modeling study to assess tsunami hazard, essentially from seismic sources, along the North shore of Hispaniola (NSOH), which is shared by the Republic of Haiti (RH) and the Dominican Republic (DR). The scope of this study included detailed tsunami inundation mapping for two selected critical sites, Cap Haitien in RH and Puerto Plata in DR. Results of this effort are reported here, and, although still limited in scope, they are within the framework and contribute to the advancement of the UNESCO IOC Tsunami and other Coastal Hazards Warning System for the Caribbean and Adjacent Regions (CARIBE EWS; von Hillebrandt-Andrade in Science 341:966-968, ). In similar work done for critical areas of the US east coast (under the auspice of the US National Tsunami Hazard Mitigation Program), the authors have modeled the most extreme far-field tsunami sources in the Atlantic Ocean basin, including: (1) a hypothetical $$M_w$$ 9 seismic event in the Puerto Rico Trench (PRT); (2) a repeat of the historical 1755 $$M_w$$ 9 earthquake in the Azores convergence zone (LSB); and (3) a hypothetical extreme $$450\,\hbox {km}^3$$ flank collapse of the Cumbre Vieja Volcano (CVV) in the Canary Archipelago. Here, tsunami hazard assessment is performed along the NSOH for these three sources, plus two additional near-field coseismic tsunami sources: (1) a $$M_w$$ 8 earthquake in the western segments of the nearshore Septentrional fault (SF), as a repeat of the 1842 event; and (2) a $$M_w$$ 8.7 earthquake occurring in selected segments of the North Hispaniola Thrust Fault (NHTF). Initial tsunami elevations are modeled based on each source's parameters and propagated with FUNWAVE-TVD (a nonlinear and dispersive long-wave Boussinesq model) in a series of increasingly fine-resolution nested grids (from 1 arc-min to 205 m) using a one-way coupling methodology. For the two selected sites, coastal inundation is computed with TELEMAC (a Nonlinear Shallow Water wave model), in finer-resolution (12-30 m) unstructured nested grids. While for the EC, PRT is a far-field source, for RH and DR, this would be local source as some of the NSOH would be affected within 1 h or is within 200 km of the PRT. This is per definitions of UNESCO IOC. Regional goes from 200 to 1000 km and within 1 and 3 h, and distant is greater than 3 h and more than 1000 km. We find that among the far-field sources CVV causes the largest impact, with up to 20-m runup at the critical sites while PRT, which is a local source for the NSOH, only causes up to 4-m runup due to its directionality; PRT, however, has both a much shorter return period and would impact the NSOH within 30 min of the earthquake. Among near-field sources, the SF event, as could be expected from a strike-slip fault, only causes a small tsunami, but the NHTF event causes up to 12-m runup in the critical sites, with the tsunami arriving within minutes of the earthquake. Hence, the latter event can be considered as the 'Probable Maximum Tsunami' (PMT; following, e.g., the US Nuclear Regulatory Commission terminology) for the NSOH. Results of detailed coastal modeling for this PMT can be used to develop maps of vulnerability for the critical sites and prepare for mitigating measures and evacuation; a few examples of such maps are given in the paper. Although a number of earlier studies have dealt with each of the far-field tsunami sources, the modeling of their impact on the NSOH and that of the near-field sources, presented here as part of a comprehensive tsunami hazard assessment study, are novel. Future work should model additional coastal sites and may consider effects of tsunamis generated by near-field submarine mass failures. [ABSTRACT FROM AUTHOR]