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SUMMARYThis paper explores the effects on tsunami simulations of the level of detail of the bathymetric grid in use. For this purpose, we expand available bathymetric data sets of the Pacific Basin in spherical harmonics. For realistic scenarios of tsunamis generated by earthquake dislocations, we conclude that an expansion to a maximum degree lmax = 40, corresponding to wavelengths of 1000 km, is sufficient to reproduce the main features of the tsunami wavefield synthesized in deep water, that is, without considering final shoaling and interaction with coastal features.

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.

In this research, we have conducted a numerical simulation to obtain the seismic source, coseismic deformation field, and the tsunami propagation of the great Lima-Peru 1940 earthquake and tsunami, based on macroseismic information and focal mechanism from the literature. The seismic dimensions of our preferred model were set at 162 km×71 km according to VIII isoseismal intensity. The slip distribution is homogeneous with a mean value of 2.7 m. The fault plane orientation was set at strike = 330∘, dip = 20∘, and rake = 90∘. The maximum simulated uplift was 1.27 m and the maximum subsidence was 0.36 m. Due to the proximity of the seismic source to the coast, the city of Huacho was uplifted around 11 cm. The fault plane of the 1940 earthquake was located in the updip near the coast. The maximum tsunami height simulated in Huacho was 1.80 m. We suggest that there is a high tsunamigenic potential near the trench to generate a shallow earthquake.

Geologically, Sulawesi Island is a complex area. It is caused by the convergence between three lithosphere plates, where the Australian Plate drifting to North, Pacific to West, and Eurasia from South to South-East respective. The future tsunami simulation was done by using SiTProS (Siam Tsunami Propagation Simulator) Version 1.5., which uses data such as earthquakes coordinate, magnitudes, focus depths, and propagation scheme, as the main input parameters in the simulations. Based on those future tsunami simulations results, the mitigation scheme chosen for Banggae District of Majene Region, West Sulawesi Province is the Vertical Tsunami Mitigation scheme. Due to its detailed parameters i.e. population details, evacuation time, distance and speed, the Vertical Tsunami Mitigation Scheme can determine the existence of shelters parameters and analyze the additional shelters needed in precise manner.

The 1783 Scilla landslide–tsunami (Calabria, southern Italy) is a well-studied event that caused more than 1500 fatalities on the beaches close to the town. This paper complements a previous work that was based on numerical simulations and was focused on the very local effects of the tsunami in Scilla. In this study we extend the computational domain to cover a wider portion of western Calabria and northeastern Sicily, including the western side of the Straits of Messina. This investigation focuses on Capo Peloro area (the easternmost cape of Sicily), where the highest tsunami effects outside Scilla were reported. Important tsunami observations, such as the wave height reaching 6 m at Torre degli Inglesi and flooding that reached over 600 m inland, have been successfully modeled but only by means of a high-resolution (10 m) topo-bathymetric grid, since coarser grids were inadequate for the purpose. Interestingly, the inundation of the small lake of Pantano Piccolo could not be reproduced by using today's coastal morphology, since a coastal dune now acts as a barrier against tsunamis. Historical analysis suggests that this dune was not in place at the time of the tsunami occurred and that a ground depression extending from the lake to the northern coast is a remnant of an ancient channel that was used as a pathway in Roman times. The removal of such an obstacle and the remodeling of the coeval morphology allows the simulations to reproduce the tsunami penetration up to the lake, thus supporting the hypothesis that the 1783 tsunami entered the lake following the Roman channel track. A further result of this study is that the computed regional tsunami propagation pattern provides a useful hint for assessing tsunami hazards in the Straits of Messina area, which is one of the most exposed areas to tsunami threats in Italy and in the Mediterranean Sea overall.

The frequent occurrence of landslide tsunami has aroused great social concern, hence an efficient approach for modeling the phenomena is required urgently. Herein, we present and supplement a meshless numerical model named ‘Tsunami Squares’ (TS). TS simulates both the landslide and its generated wave using an updated numerical scheme that has enhanced computational efficiency. TS also provides an artful way of approximating linear dispersive wave propagation and non-linear wave inundation that makes it quite capable of simulating real-scale events. A well-designed test that compares TS output with an analytical formula for a tsunami propagation calculation provides firm validation of the approach. We then applied the ‘Tsunami Squares’ to simulate the 1792 Unzen-Mayuyama mega slide and generated tsunami. This event remains the largest volcanic disaster in the history of Japan. Landslide dynamics simulated by TS coincide with historical reports and the known geometry of landslide deposits. The model output of tsunami runup heights well match the observed values recorded by the locations of historical ‘Tsunami Stones’. This well documented and data-rich case further validates the ‘Tsunami Squares’ model and the excellent reproduction of the 1792 event provides new insights for better understanding of landslide tsunami hazards.

Ischia Island has been repeatedly affected by mass collapses, which are mainly caused by the steepness of the main peak (Mt Epomeo) and by phenomena related to its volcanic activity. The most relevant cases of mass failure studied in the literature and postulated to be tsunamigenic cover a wide spectrum of sizes, from sector collapse to small-volume mass transports. Tsunamis generated by landslides in Ischia may affect the coast of the Campania mainland, including the Gulf of Naples. The focus of this work is an evaluation of the pattern of the maximum tsunami energy. To this purpose, we perform a series of numerical simulations by moving the same landslide source in different hypothetical positions around the island. The landslide dynamics are computed through the code UBO-BLOCK, and the tsunami propagation by employing the code UBO-TSUFD, both developed in-house. The final goal is to characterize the coastal areas of the Campania mainland most exposed to tsunami attack from Ischia sources. It is found that the position of the landslide deeply influences the distribution of the tsunami elevation in the coastal stretch north of the Procida Mt, while, remarkably, it is irrelevant inside the Gulf of Naples where the bathymetric effect prevails.

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.

Earthquake rupture dynamic models capture the variability of slip in space and time while accounting for the structural complexity which is characteristic for subduction zones. The use of a geodynamic subduction and seismic cycling (SC) model to initialize dynamic rupture (DR) ensures that initial conditions are self-consistent and reflect long-term behavior. We extend the 2D geodynamical subduction and SC model of van Zelst et al. (2019) and use it as input for realistic 3-dimensional DR megathrust earthquake models. We follow the subduction to tsunami run-up linking approach described in Madden et al. (2020), including a complex subduction setup along with their resulting tsunamis. The distinct variation of shear traction and friction coefficients with depth lead to realistic average rupture speeds and dynamic stress drop as well as efficient tsunami generation. We here analyze a total of 14 subduction-initialized 3D dynamic rupture-tsunami scenarios. By varying the hypocentral location along arc and depth, we generate 12 distinct unilateral and bilateral earthquakes with depth-variable slip distribution and directivity, bimaterial, and geometrical effects in the dynamic slip evolutions. While depth variations of the hypocenters barely influence the tsunami behavior, lateral varying nucleation locations lead to a shift in the on-fault slip which causes time delays of the wave arrival at the coast. The fault geometry of our DR model that arises during the SC model is non-planar and includes large-scale roughness. These features (topographic highs) trigger supershear rupture propagation in up-dip or down-dip direction, depending on the hypocentral depth.In two additional scenarios, we analyze variations in the energy budget of the DR scenarios. In the SC model, an incompressible medium is assumed (ν=0.5) which is valid only for small changes in pressure and temperature. Unlike in the DR model where the material is compressible and a different Poisson’s ratio (ν=0.25) has to be assigned. Poisson’s ratios between 0.1 and 0.4 stand for various compressible materials. To achieve a lower shear strength of all material on and off the megathrust fault and to facilitate slip, we increase the Poisson ratio in the DR model to ν=0.3 which is consistent with basaltic rocks. As a result, larger fault slip is concentrated at shallower depths and generates higher vertical seafloor displacement and earthquake moment magnitude respectively. Even though the tsunami amplitudes are much higher, the same dynamic behavior as in the twelve hypocenter-variable models can be observed. Lastly, we increase fracture energy by changing the critical slip distance in the linear slip-weakening frictional parameterization. This generates a tsunami earthquake (Kanamori, 1972) characterized by low rupture velocity (on average half the amount of s-wave speed) and low peak slip rate, but at the same time large shallow fault slip and moment magnitude. The shallow fault slip of this event causes the highest vertical seafloor uplift compared to all other simulations. This leads to the highest tsunami amplitude and inundation area while the wavefront hits the coast delayed compared to the other scenarios.

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.

The paper deals with the analysis of the propagation, heights, and arrival times of a tsunami that may occur on the coastal areas of Cyprus and Eastern Mediterranean in the case of an earthquake in southern Cyprus. Following a review of the seismic risk and historical earthquakes which occurred in southern Cyprus, it was concluded that this region may be subject to high vulnerability if a tsunami occurs. A study was conducted on the numerical modelling of a possible tsunami generated by movement along the fault of the 1222 Paphos earthquake. The region where the earthquake occurred can be attributed to the Cyprian Arc in the southwest of Cyprus. This arc is one of the most active seismic zones in the Mediterranean, which has led to the occurrence of earthquakes from submerged seismogenic sources. A methodology is used to simulate tsunami wave propagation for the Eastern Mediterranean coastal areas which requires the initial wave due to fault parameters as well as the bathymetry data. The GEBCO30 bathymetry data are used which have a grid spacing of 0.30 arc min. The fault parameters are deduced from the maximum stress directions and source geometry of the region from the moment tensor solutions derived from analyzing of earthquake waveforms. The numerical tsunami propagation model was performed by using SWAN code. The simulated highest tsunami heights were 4.02 m in Kouklia (Cyprus); 2.85 m in Paphos Ktima (Cyprus); 2.58 in Episkopi (Cyprus); 2.06 in Peyia (Cyprus); 1.76 in Yennadhi, Rhodes (Greece); 1.53 in Burg Migheizil (Egypt); 1.46 m in Tarabulus (Lebanon); 1.39 m in Bur Said (Egypt); 1.28 in Al-Burj (Egypt); and 0.60 in Mugla-Aksaz (Turkey). The results of the model outline the extent of the tsunami waves of damaging size, but destructive event in the region.

Tsunami propagating into a coastal river can severely damage hydraulic structures including bridge piers as reported during past tsunami events. Hence, in the present study, laboratory experiments are performed initially by generating tsunami bores on to a wet bed in a 24m long, 0.8m wide wave flume and later in a 12mx0.5mx0.465m recirculating channel to maintain a time scale of 1:6 required as per Froude scaling to observe reliable scour depth at the pier model. Three-dimensional flow velocities (using rigid bed) and scour patterns, depths (using mobile bed) around a circular bridge pier model were obtained to understand the scour process. Finally, the scour depth due to tsunami bore is compared to empirical steady flow scour estimations. Therefore, the present study proposes new scour design standards for bridge piers or vertical evacuation towers which are already inundated by the first wave of tsunami.

This study aims to simulate tsunami wave heights and their travel time toward the WestKalimantan coastal area. A Nuclear Power Plant (NPP) will be developed in a coastal area in the WestKalimantan Province, Indonesia. The two scenarios of events that may trigger the tsunami waves are volcanicevents caused by Mount Krakatau located in the Sunda Strait and tectonic subduction located at the IndianOcean on the west side of the Sunda Strait. Modeling the tsunami propagation using a finite-element-basedhydrodynamic model developed by the US Army Corps of Engineer, namely the Surface-water ModelingSystem (SMS), is carried out. The model simulates tsunami wave propagation for six alternative locations atthe proposed site of NPP. The model domains consist of Sunda Strait and Karimata Strait domains. The SundaStrait domain model is validated by the observed historical tsunami heights reaching the 12 locations inLampung, Banten, West Java, and Jakarta of Indonesia. The model validations show a good agreement. Thevalidated hydrodynamic model results of the Sunda Strait model are used as the boundary conditions for theKarimata Strait domain model. The Karimata Strait model results show that the peaks of tsunami wave heightsthat reach the western Kalimantan coast are between 12 cm and 116 cm. The minimum wave height peak thatreaches the six prospective locations is 12 cm, which is located in Sambas Regency.

We propose a two-layer model with two different axes of integration and a well-balanced finite volume method. The purpose is to study submarine avalanches and generated tsunamis by a depth-averaged model with different averaged directions for the fluid and the granular layers. Two-layer shallow depth-averaged models usually consider either Cartesian or local coordinates for both layers. However, the motion characteristics of the granular layer and the water wave are different: the granular flow velocity is mainly oriented downslope while water motion related to tsunami wave propagation is mostly horizontal. As a result, the shallow approximation and depth-averaging have to be imposed (i) in the direction normal to the topography for the granular flow and (ii) in the vertical direction for the water layer. To deal with this problem, we define a reference plane related to topography variations and use the associated local coordinates to derive the granular layer equations whereas Cartesian coordinates are used for the fluid layer. Depthaveraging is done orthogonally to that reference plane for the granular layer equations and in the vertical direction for the fluid layer equations. Then, a finite volume method is defined based on an extension of the hydrostatic reconstruction. The proposed method is exactly well-balanced for two kind of stationary solutions: the classical one, when both water and granular masses are at rest; the second one, when only the granular mass is at rest. Several tests are presented to get insight into the sensitivity of the granular flow, deposit and generated water waves to the choice of the coordinate systems. Our results show that even for moderate slopes (up to 30◦), strong relative errors on the avalanche dynamics and deposit (up to 60%) and on the generated water waves (up to 120%) are made when using Cartesian coordinates for both layers instead of an appropriate local coordinate system as proposed here. Ministerio de Economía y Competitividad (MINECO). España European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER) Agence Nationale de la Recherche. France European Research Council (ERC)

A numerical model that simulates the propagation of tsunamis produced by submarine earthquakes was applied to the Caspian Sea. The model was first applied to the June 1990 (Rudbar) earthquake and our results proved to be coherent with previous simulations. It was also applied to the Krasnovodsk earthquake (1895), which had not been simulated before, and it was found that the coastal area was flooded by a tsunami, as reported in literature. Nevertheless, it was a rather local effect since the tsunami was generated in very shallow waters. Some worst-case hypothetical earthquakes were simulated in the most seismically active regions of the Caspian. In general, both the east and west coasts of the central Caspian Sea would be the most affected by these earthquake-induced tsunamis, with potential significant effects in some cases in cities such as Baku.

Tsunami overland flow may cause severe destruction to the affected coastal area. Several tsunamis had hit Indonesia. Studies have shown that there is a high probability of a massive earthquake in the Mentawai fault, Sumatra, Indonesia. A massive earthquake with a magnitude of over 8 Mw might occur in the next 50 years. The nearshore tsunami propagation and inundation in Painan City, West Sumatra, Indonesia, is assessed using HEC-RAS. Various land cover types are simulated to investigate their effects on the tsunami overland flow. The model showed satisfactory results. The model can show the known behaviors of tsunami propagation in urban areas and in rivers. It was found that there is a significant effect of land cover types on the inundation at the coast. Inundation depth increases with roughness along the coast. On the other hand, high roughness decreases the inundated area. Furthermore, the land cover has a significant effect on the velocity. The velocity is much lower in higher Manning’s value. Simulation with a high surface roughness shows a significant reduction in both inundation area and velocity. The high roughness causes a blockage effect for tsunami propagation. Thus, the Tsunami cannot penetrate further inland. The information can be used for land use control suggestions. These provide significant information for future mitigation plans, e.g., placement of evacuation buildings and evacuation routes.

Shallow water equations were analyzed numerically for simulation of tsunami propagation from the source area to coastal zone of Mentawai Islands along West Sumatra Island. A triangular mesh was set for spatial discretization and a system of partial differential equation is reduced to a system of ordinary differential equations. Initial displacement based on Okada model was applied. Our numerical techniques were demonstrated with a simulation of tsunami generated from an earthquake with epicenter near South Pagai Island, Mentawai Islands, Indonesia.

In the present study, the local tsunami amplification observed in Ryori Bay, located on the Sanriku coast of Japan, was investigated using numerical simulations. Large-scale tsunami propagation simulations and tsunami inundation simulations for the bay were systematically conducted to estimate and model the 2011, 1933, and 1896 tsunamis that occurred off the Sanriku coast and which resulted in large run-ups. The simulation results, which are moderately consistent with observations, presented larger run-up heights and inundations for the 1933 and 1896 tsunamis (which followed relatively small earthquakes) compared to those of the 2011 tsunami (which followed a larger earthquake). Furthermore, the frequency analysis indicated that the former two tsunamis comprised higher predominant components. A tsunami inundation simulation using parametrized synthetic waveforms was conducted to identify the contributing factors associated with the large amplification and run-ups. The results indicated that the predominant components are significantly amplified in the bay and the initial decrease in the water surface elevation prior to the primary waves of the two tsunamis leads to an increase in their run-up heights. Furthermore, the simulated waveforms of the tsunamis revealed that the 1933 and 1896 tsunamis had their wavefronts changed into a steep wavefront, i.e., a bore-like wave, during their wave developments in the bay, attributed to shoaling, narrowing bay width, and the nonlinear effect of the wave. These results, therefore, indicate that bores which are known to generate large run-up heights were generated in the bay during the two tsunamis.

Tsunami propagation over the entire Dayawan Bay was simulated using a 2D shallow water model to provide hydrodynamic boundary conditions for a 3D flow model, by which tsunami propagation inside the inlet of water-intake basin of the Dayawan Nuclear Power Plant (DNPP) was simulated. The 2D model covers the whole bay plus a little extension of the waters around the bay mouth. The sea side open boundary of the 2D model is generated from a superposition of an assumed tsunami process on a tide with exceedance probability of 10%. The event of encounter of a 10-min highest waters of the assumed tsunami process with such level of tide is estimated to be approximately a return period of 1490 years. Tsunami run-up in front of the revetment of the pump room was simulated using the 3D flow models. The rubble-mound breakwater was treated as porous medium in the simulation. Computational results of flow velocity indicate that tsunami propagation inside the basin is effectively prevented by the east breakwater. Computational results of waters in front of the revetment of the pump room indicate that the possible maximum water level is lower than the present elevation of the revetment, therefore the pump room has low risk of inundation.

The effect of giant tsunamis such as the Indian Ocean Tsunami in 2004 and the Great East Japan Earthquake Tsunami in 2011 has been devastating. In this study, a numerical simulation of the tsunami has been developed to estimate the physical characteristics of tsunamis and their effect on human society. Several laws and equations have been introduced for the simulation of tsunami propagation in the ocean, tsunami refraction, and tsunami run-up on land under a stable computational condition with acceptable accuracy. Our proposed method has been accepted as the world standard since 1997 and has been widely distributed to many countries through UNESCO.1) Computer graphic animations prepared by using the results of numerical simulation have been effectively used in public education and to increase the understanding of behaviors of the tsunami on the earth. When the numerical prediction of tsunami becomes possible with sufficient accuracy, then their results can be used to predict future damages and prevent the occurrence of a disaster. Data in the past were collected and expressed in terms of a newly introduced tsunami intensity which is related to the locally observed tsunami heights.

This paper aims at best describing the submarine landslide which induced partial submersion of the atolls of Mururoa and Fangataufa in 1979. More precisely, waves propagated along the south coast of Mururoa atoll and penetrated into its lagoon some minutes after the landslide triggering (t = 0 s), whereas a train of eight water waves reached the runway located on the north-east coast of Fangataufa (40 km south of Mururoa) between t = 7 min 30 s and t = 20 min. A numerical model based on shallow water equations is used to simulate the landslide as well as the associated tsunami. Saint-Venant equations are used to propagate the tsunami in coastal areas, whereas the offshore propagation is simulated by solving weakly nonlinear Boussinesq equations. Low- and high-resolution nested grids are used to simulate the tsunami propagation in deep sea and in shallow waters, respectively. Several scenarios have been tested to reproduce the observed water and run-up heights in the near and far fields. The best scenarios correspond to a landslide with a volume in the range (75–90 Mm3) (for a basal friction angle of 35°) and with a basal friction angle in the range (30°–40°) (for a volume of 80 Mm3). These results have been completed by a parametric study on the slide parameters.

Recent studies suggest that the tsunami speed can be slowed down by around 1% due to Earth elasticity, water compressibility and density stratification. Analytical solutions of wave dispersion relationship, accounting for such effects, were found in previous studies. In this paper, we investigate the additional effects of water viscosity, ocean stratification due to temperature/salinity and numerical dispersion. Theoretical solutions are derived and checked with known solutions. All the formulas are then simplified for long tsunamis waves so that the propagation speed can be calculated explicitly. The simplified solutions are evaluated using realistic geophysical parameters. For a typical tsunami wavelength of ∼200km, the viscous effect is found to be negligible; ocean stratification due to temperature/salinity causes significant speed reduction because of the high density change rate, which has been ignored before. We also evaluate the numerical dispersion of tsunami simulations, which is shown to be potentially comparable to physical dispersion.

We apply a genetic algorithm (GA) to find the optimized unit sources using dispersive tsunami synthetics to estimate the tsunami source of the 2012 Haida Gwaii earthquake. The optimal number and distribution of unit sources gives the sea surface elevation similar to that from our previous slip distribution on a fault using tsunami data, but different from that using seismic data. The difference is possibly due to submarine mass failure in the source region. Dispersion effects during tsunami propagation reduce the maximum amplitudes by up to 20% of conventional linear long wave propagation model. Dispersion effects also increase tsunami travel time by approximately 1 min per 1,300 km on average. The dispersion effects on amplitudes depend on the azimuth from the tsunami source reflecting the directivity of tsunami source, while the effects on travel times depend only on the distance from the source.

Early tsunami warning critically hinges on rapid determination of the tsunami hazard potential in real-time, before waves inundate critical coastlines. Tsunami energy can quickly characterize the destructive potential of generated waves. Traditional seismic analysis is inadequate to accurately predict a tsunami’s energy. Recently, two independent approaches have been proposed to determine tsunami source energy: one inverted from the Deep-ocean Assessment and Reporting of Tsunamis (DART) data during the tsunami propagation, and the other derived from the land-based coastal global positioning system (GPS) during tsunami generation. Here, we focus on assessing these two approaches with data from the March 11, 2011 Japanese tsunami. While the GPS approach takes into consideration the dynamic earthquake process, the DART inversion approach provides the actual tsunami energy estimation of the propagating tsunami waves; both approaches lead to consistent energy scales for previously studied tsunamis. Encouraged by these promising results, we examined a real-time approach to determine tsunami source energy by combining these two methods: first, determine the tsunami source from the globally expanding GPS network immediately after an earthquake for near-field early warnings; and then to refine the tsunami energy estimate from nearby DART measurements for improving forecast accuracy and early cancelations. The combination of these two real-time networks may offer an appealing opportunity for: early determination of the tsunami threat for the purpose of saving more lives, and early cancelation of tsunami warnings to avoid unnecessary false alarms.

Aoyama, Y.; Adityawan, M.B., Widiyanto, W., Mitobe, Y., Komori, D., and Tanaka, H., 2016. Numerical Study on Tsunami Propagation into a River. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1017 - 1021. Coconut Creek (Florida), ISSN 0749-0208. The Tohoku Earthquake and Tsunami in 2011 caused serious damage not only to coastal structures, but also to riverine infrastructure due to long distance of wave propagation into rivers located on the coast facing the Pacific Ocean. Although there have been numerous investigations on tsunami, limited number of studies have been made for tsunami propagation into a river channel. This study investigates tsunami propagation into a river numerically by comparing with laboratory experiment data. The present numerical simulation is based on shallow water equations, which are solved with the MacCormack sch...

A large earthquake event generated from the nearby Cascadia Subduction Zone would possibly generate a significant tsunami event which could affect the west coast of Canada. In this study, to critically assess the effects of a tsunami on the District of Tofino on Vancouver Island, British Columbia, tsunami simulations were performed. As a result of tsunami propagation and inundation simulations, it was found that for earthquakes Mw9.0 or greater, the central part of the Esowista Peninsula on which Tofino is located will be completely inundated. The authors have also conducted tsunami evacuation simulations using an agent-based model developed by Takabatake et al. (2017). This evacuation model considered Tofino's large fluctuation in residents due to seasonal tourism in a number of selected scenarios. Using the model, the authors also conducted a sensitivity analysis to investigate effects of the change in evacuation behaviour on the mortality rate. The results showed that a significant number of casualties would occur in Tofino, especially if an earthquake was to occur at night. It was also shown to be important to consider the capacity of evacuation buildings when directing evacuees, especially the elderly. In addition, the present study clarified that the effects of evacuation start time and route choices on the mortality rate would vary significantly according to a population distribution scenario even in the same study area. It was thus highlighted that conducting sensitivity analysis under varied population distribution scenarios is important to understand properly the uncertainty associated with tsunami evacuation.

Fifteen years since the 2004 Indian Ocean tsunami, which caused massive destruction around the Andaman Sea, people have participated in efforts to reduce tsunami risks in Indonesia. However, the most important question continues to be on whether such efforts are sufficient in dealing with tsunami risks. Among the most striking challenges here is bridging the gap in tsunami risk reduction between the Sumatra mainland and among communities in several small islands. Thus, this research aims to investigate the recent conditions of selected towns/cities in tsunami-prone small islands and identify the impediments to their tsunami hazard preparedness. It focuses on comparing efforts in terms of available facilities for tsunami evacuation plans and the tsunami estimated time of arrival (ETA), which is computed based on deterministic tsunami propagation models. In this regard, five of the observed locations are classified as being in a critical tsunami preparedness condition, namely Balai island, Lahewa of Nias Island, Sabeugunggung of North pagai Island, Surat Aban of South Pagai island, and Enggano Island. Most of them have limited space for tsunami evacuation and a short tsunami ETA, which constitutes an extreme condition requiring immediate tsunami mitigation measures. One possible approach is to construct a vertical tsunami evacuation building or modify existing buildings that can be used for tsunami evacuation on the islands. This article also highlights societal aspects related to tsunami preparedness.

This paper addresses the tsunami propagation and subsequent coastal areas flooding by means of a depth-integrated numerical model. Such an approach is fundamental in order to assess the inundation hazard in coastal areas generated by seismogenic tsunami. In this study we adopted, an interdisciplinary approach, in order to consider the tsunami propagation, relates both to geomorphological characteristics of the coast and the bathymetry. In order to validate the numerical model, comparisons with results of other studies were performed. This manuscript presents first applicative results achieved using the weakly dispersive Boussinesq model in the field of tsunami propagation and coastal inundation. Ionic coast of Sicily (Italy) was chosen as a case study due to its high level of exposure to tsunamis. Indeed, the tsunami could be generated by an earthquake in the external Calabrian arc or in the Hellenic arc, both active seismic zones. Finally, in order to demonstrate the possibility to give indications to local authorities, an inundation map, over a small area, was produced by means of the numerical model.

When a large earthquake occurs in an offshore region, a tsunami is generated. The generation and propagation can be mathematically described based on equation of motion. This chapter visualizes and overviews tsunami generation and propagation to obtain an overall grasp of tsunamis and elucidate their fundamental nature. Section 2.1 illustrates the tsunami generation and propagation caused by a huge earthquake. We use a dynamic rupture scenario constructed for an anticipated huge earthquake in the Nankai Trough, Japan. Section 2.2 shows a simple model for the generation and propagation. While the generation is basically independent of gravity, gravity is the main force to move tsunami. Section 2.3 describes the fundamental properties of the propagation. Tsunami propagation depends on the wavelength and sea depth. Also, when the sea depth is very shallow, tsunami becomes to show nonlinear characteristics. Section 2.4 summarizes the main points of tsunami generation and propagation.

In spite of the fact that the great majority of seismic tsunami is generated in ocean domains, smaller basins like the Ionian Sea sometimes experience this phenomenon. In this investigation, we study the tsunami hazard associated with the Ionian Sea fault system. A scenario-based method is used to provide an estimation of the tsunami hazard in this region for the first time. Realistic faulting parameters related to four probable seismic sources, with tsunami potential, are used to model expected coseismic deformation, which is translated directly to the water surface and used as an initial condition for the tsunami propagation. We calculate tsunami propagation snapshots and mareograms for the four seismic sources in order to estimate the expected values of tsunami maximum amplitudes and arrival times at eleven tourist resorts along the Ionian shorelines. The results indicate that, from the four examined sources, only one possesses a seismic threat causing wave amplitudes up to 4 m at some tourist resorts along the Ionian shoreline.

Fragility functions in terms of flow depth, flow velocity and hydrodynamic force are developed to evaluate structural vulnerability in the areas affected by the 2009 Samoa earthquake and tsunami. First, numerical simulations of tsunami propagation and inundation are conducted to reproduce the features of tsunami inundation. To validate the results, flow depths measured in field surveys and waveforms measured by Deep-ocean Assessment and Reporting of Tsunamis (DART) gauges are utilized. Next, building damage is investigated by visually interpreting changes between pre- and post-tsunami high-resolution satellite images. Finally, the data related to tsunami features and building damage are integrated using Geographic Information System (GIS), and tsunami fragility functions are developed based on the statistical analyses. From the developed fragility functions, we quantitatively understood the vulnerability of a coastal region in American Samoa characterized by steep terrains and ria coasts.

We present a method of tsunami data assimilation using a linear dispersive model in order to provide an accurate tsunami early warning. To speed up the assimilation process, we use the Green’s function-based tsunami data assimilation, in which the Green’s functions are calculated in advance with linear dispersive tsunami propagation models. We demonstrate a test case in the Nankai Trough off southwest Japan, with a source model similar to the main shock of the 2004 off the Kii Peninsula earthquake (M7.4) which generated tsunamis with dispersive characteristics. We show that assimilation of existing ocean bottom pressure gauge data can rapidly forecast the tsunami arrival time and the maximum height of the first tsunami peak along the coast of Shikoku and Kyushu Islands. Both the linear long-wave model and the linear dispersive model can accurately forecast the tsunami height, but the linear dispersive model can predict the tsunami arrival time more accurately for the tested earthquake.

We show the ionospheric signatures of the 28 October 2012 Haida Gwaii tsunami in both the total electron content (TEC) and the airglow layer. In addition, previously reported ionospheric signatures from the 11 March 2011 Tohoku and 27 February 2010 Chile tsunamis are reexplored in comparison to the newer Haida Gwaii detections. These events provide excellent test cases in the study of tsunami-ionospheric coupling efficiency, which is most notably affected by the observation geometry, tsunami propagation direction, and background ionospheric density. A simple calculation is developed that incorporates observation geometry to predict the relative coupling efficiency. The predictions are compared to the TEC observations and limitations are discussed.

The tsunami hazard for the coast of the Sea of Okhotsk requires a careful analysis, because this sea will be a zone of responsibility for the Tsunami Warning Service for the Far East coast of Russia. While it is not subject to such hazards on the part of seismogenic zones that can produce dangerous tsunamis, nevertheless the Sea of Okhotsk is open for penetration of tsunamis that can be produced by sources in other tsunamigenerating zones of the Kuril–Kamchatka region, as well as those of the entire Pacific Ocean. The tsunami hazard for the coast of the Sea of Okhotsk is examined here on the basis of historical observations and the results of numerical simulation for tsunami propagation from hypothetical rupture zones of near and distant earthquakes. It is shown that the real tsunami hazard can only emanate from those regional earthquakes with magnitudes 8.5 or greater that occur in the Kuril–Kamchatka seismogenic zone. Among the remote tsunamigenerating zones in the Pacific, the most dangerous locations are the rupture zones of mega-earthquakes of the class M9 that come from the South America zone and from Papua–New Guinea. These can produce water waves with amplitudes as great as 5 m along the entire coast of the Sea of Okhotsk.

The reliability of the narrative of the Biblical Exodus has been subject of heated debate for decades. Recent archaeological studies seem to provide new insight of the exodus path, and although with a still controversial chronology, the effects of the Minoan Santorini eruption have been proposed as a likely explanation of the biblical plagues. Particularly, it has been suggested that flooding by the associated tsunamis could explain the first plague and the sea parting. Recent modelling studies have shown that Santorini’s tsunami effects were negligible in the eastern Nile Delta, but the released tectonic stress could have triggered local tsunamigenic sources in sequence. This paper is aimed to a quantitative assessment of the potential role of tsunamis in the biblical parting of the sea. Several “best case” scenarios are tested through the application of a numerical model for tsunami propagation that has been previously validated. The former paleogeographic conditions of the eastern Nile Delta have been implemented based upon recent geological studies, and several feasible local sources for tsunamis are proposed. Tsunamis triggered by submarine landslides of 10–30 km3 could have severely impacted the northern Sinai and southern Levantine coasts but with weak effects in the eastern Nile Delta coastline. The lack of noticeable flooding in this area under the most favorable conditions for tsunamis, along with the time sequence of water elevations, make difficult to accept them as a plausible and literally explanation of the first plague and of the drowning of the Egyptian army in the surroundings of the former Shi-Hor Lagoon.

The linear Boussinesq equations are an ideal model for transoceanic propagation of tsunamis. However, they are impractical for real-time application because Boussinesq-type equation models rely on a fine grid system and therefore require a huge computational domain. Thus, shallow-water equations models are the preferred method of predicting propagation and run-up of near- and far-field tsunamis since they produce fairly accurate results with a much smaller computational requirement. There may be an additional benefit in including physical dispersion effects in numerical models since shallow-water equations theoretically neglect the effect of dispersion on the transoceanic propagation of tsunamis. In this study, a modified finite difference scheme was proposed that adds terms to the linear shallow-water equations in order to account for varying water depths. The proposed model was verified by applying it to tsunami propagation over a submerged shoal and the results were compared with those of the well-known Boussinesq equations model, FUNWAVE. The proposed model was further tested by simulating transoceanic tsunami propagation on real topographies and comparing the numerical results with available observed data.

Tsunamis induced by rock slides constitute a severe hazard towards coastal fjord communities. Fjords are narrow and rugged with steep slopes, and modeling the short-frequency and high-amplitude tsunamis in this environment is demanding. In the present paper, our ability (and the lack thereof) to simulate tsunami propagation and run-up in fjords for typical wave characteristics of rock-slide-induced waves is demonstrated. The starting point is a 1 : 500 scale model of the topography and bathymetry of the southern part of Storfjorden fjord system in western Norway. Using measured wave data from the scale model as input to numerical simulations, we find that the leading wave is moderately influenced by nonlinearity and dispersion. For the trailing waves, dispersion and dissipation from the alongshore inundation on the traveling wave become more important. The tsunami inundation was simulated at the two locations of Hellesylt and Geiranger, providing a good match with the measurements in the former location. In Geiranger, the most demanding case of the two, discrepancies are larger. The discrepancies may be explained by a combinations of factors, such as the accumulated errors in the wave propagation along large stretches of the fjord, the coarse grid resolution needed to ensure model stability, and scale effects in the laboratory experiments.

While the tsunami propagation, run-up and inundation has received considerable attention in literature, the associated boundary layer dynamics and induced sediment transport have received relatively little attention. Recently, Williams and Fuhrman (2016) simulated a series of tsunami scale boundary layers, emphasizing that they are simultaneously both current- and wave-like due to their long duration yet unsteady nature. They viewed the tsunami as a time varying current, something that has also been done by Larsen et al. (2017) and Larsen et al. (2018) in studies of tsunami-induced scour around monopile foundations. This approach is valid sufficiently far off-shore, but nearshore, the effects of the free-surface will inevitably become important. While difficult due to the large scales involved, the run-up and inundation can likewise be studied experimentally (Sriram et al. 2016). In this work the run-up process of full-scale tsunamis will be simulated in detail using CFD, which can naturally resolve shorter dispersive waves, wave breaking and boundary layer dynamics.

Tsunami warning is classically based on two fundamental tools: the first one concerns the source parameters estimations, and the second one is the tsunami amplitude forecast. We presented in the first companion paper how the seismic source parameters are evaluated, and this second article describes the operational aspect and accuracy of the estimation of tsunami height using tsunami numerical modelling on a dedicated supercomputer (2.5 T-flops). The French Polynesian tsunami warning centre developed two new tsunami forecast tools for a tsunami warning context, based on our tsunami propagation numerical model named Taitoko. The first tool, named MERIT, that is very rapid, provides a preliminary forecast distribution of the tsunami amplitude for 30 sites located in French Polynesia in less than 5 min. In this case, the coastal tsunami height distribution is calculated from the numerical simulation of the tsunami amplitude in deep ocean using an empirical transfer function inspired by the Green Law. This method, which does not take into account resonance effects of bays and harbour, is suitable for rapid and first estimation of the tsunami danger. The second method, named COASTER, which uses 21 nested grids of increasing resolutions, gives more information about the coastal tsunami effects about the flow velocities, the arrival time of the maximal amplitude, and the maximal run-up height for five representative sites in 45 min. The historical tsunamis recorded over the last 22 years in French Polynesia have been simulated with these new tools to evaluate the accuracy of these methods. The results of the 23 historical tsunami simulations have been compared to the tide-gauge records of three sites in French Polynesia. The results, which are quite encouraging, shows standard errors of generally less than a 2 factor : the maximal standard error is 0.38 m for the Tahauku Bay of Hiva-Oa (Marquesas islands).

At least five catastrophic tsunami events have affected the Iberian Atlantic coasts during the last 7000 years. During this time, the former Gulf of Tartessos evolved towards the present marshland area, in the lower Guadalquivir valley (SW Spain). Ancient cultures flourished and vanished around this waterbody which, with its tidal dynamics, was an essential part of their living environment. A numerical modeling study on oceanographic conditions (tide and tsunami propagation) in the former Gulf of Tartessos has been carried out, in order to improve our insight on how they could have influenced the human activities in this area. The model solves the 2D depth-averaged hydrodynamic equations with appropriate initial and boundary conditions for tides and tsunamis. The model has been tested through simulation of tides under present bathymetry and of past tsunamis for which historical records exist. Then the bathymetry of the Gulf of Tartessos has been reconstructed for 2200 and 4000 years BP. The two main tidal semidiurnal and diurnal constituents have been simulated. Results indicate that they suffer a strong attenuation in the Gulf for both bathymetries, with significant currents only in its entrance. The known main active faults in the Gulf of Cadiz and the 1755 Lisbon source have been selected as case studies of tsunami propagation in the former Gulf of Tartessos. The 1755 Lisbon tsunami represented the worst case situation, and its numerical simulation has been subjected to several sensitivity tests. Results reveal negligible impacts for the inner shoreline of the Gulf of Tartessos, but severe damage could have been produced along the Atlantic coasts of SW Spain, from Cadiz to Huelva.