Historical Tsunami Research Articles

Record of two Late-Holocene tsunamis along the north Peruvian coast and their relation to archaeological sites of the Chicama River valley

South America’s Pacific margin is subject to recurring subduction-zone earthquakes that have generated devastating historical tsunamis, as well as earlier events impacting indigenous populations that have lived along the region’s rich upwelling coastlines throughout the Holocene. Despite recurring events, the geologic record of paleo-tsunamis is relatively sparse. Here we report evidence for two paleo-tsunamis striking the Chicama River coastline (8°S) around 2.8 and 2.0 ka. The two sedimentary deposits are amalgamated in many locations and can be difficult to distinguish, but floodplain or shoreface deposits separate the two units when traced landward and seaward, respectively. The magnitude of each event was sufficient to erode coarse cobbles (13–25 cm) from the shoreface and transport them ~100 m before being deposited as rapidly thinning and fining gravel units. Based on the distribution of mobilized cobbles, we consider plausible flow characteristics for the two tsunamis suggesting that each was on the order of at least a few meters in height with most of the cobble transport occurring only under critical to supercritical flow at the wave front. Previous archaeological reports from the area correctly recognized the older tsunami event but did not describe the younger, better-preserved second event. Further, we revisit the archaeological evidence for the tsunami and recast the older event as likely being more moderate than previously suggested. Broader archaeological evidence from this 30-km reach of the Chicama valley shoreline also suggests that the late Cupisnique to Salinar and Gallinazo cultures were not severely disrupted by the tsunamis, even with these events undoubtedly impacting nearshore inhabitants at the time.

Evaluation of Public Buildings as Tsunami Evacuation Vertical Based on Tsunami History

Evaluation of Public Buildings as Tsunami Evacuation Vertical Based on Tsunami History

Computation Models for Tsunami Wave Propagation using Extended Cellular Automata

Using traditional models to simulate the propagation of large-scale tsunami waves leads to low accuracy and low efficiency. To ensure higher timing accuracy of tsunami wave spread, built an enhanced model that connects cellular automata with an existing model of tsunami waves. To determine the ideal time step value, our approach considers how time steps affect simulation accuracy. The spread of tsunami waves using a two-dimensional cellular automata model was used to test the model. Extending cellular automata (CA) models for tsunami wave propagation involves incorporating additional complexity and realism to better simulate the dynamics of these natural phenomena. The findings indicate that 1/4 of the time required for all of the cellular material to be traversed is the ideal time step for the tsunami wave spread global cellular automata simulation program. With a mean accuracy of 86.78% and a mean Kappa coefficient of 0.6443, this model demonstrated strong temporal and spatial consistency when compared to historical tsunami wave data from NOAA. Combining the Kappa coefficient with extended cellular automata (ECA) can be beneficial in various applications, particularly those involving classification tasks or spatial modeling. The earliest arrival tsunami wave spread can be predicted and simulated using this approach.

Large seafloor rupture caused by the 1956 Amorgos tsunamigenic earthquake, Greece

In the Mediterranean Sea, the probability that a large earthquake-triggered tsunami will occur in the coming decades is high. Historical tsunami database informs us on their geographical occurrence but their sources, i.e., the faults that slipped during earthquakes and displaced the seafloor to generate tsunamis, are often unknown. Here we identify the submarine rupture of the Amorgos earthquake that on July 9, 1956, triggered the largest mediterranean tsunami in the past two centuries. Using submarines, we explored major normal faults in the epicentral area, and discovered a large surface rupture along the 75-km long Amorgos fault. The 9.8-16.8-m large seafloor offset is compatible with a Mw7.5 event. This finding prompts a reassessment of the largest (≥20 m) tsunami wave origin, previously attributed to earthquake-triggered submarine mass-wasting. It demonstrates that tsunami source can be determined several decades after an event, a key information to better assess future seismic and tsunami hazards.

Pengembangan Potensi Wisata dan Kesesuaian Lahan Wisata terhadap Resiko Tsunami di Kawasan Teluk Pacitan

The southern coastal region of Pacitan Regency, particularly in six districts, namely Ngadirejo, Sudimoro, Kebonagung, Donorojo, Pringkuku, and Pacitan District, is classified as a high-risk tsunami red zone. Based on the research findings, the Pacitan Bay area consists of two villages, namely Sidoarjo Village and Ploso Village in Pacitan Distict. Sidoarjo Village covers an area of 8.36 km², while Ploso Village covers 3.66 km², making the total area 12.02 km² or 1202 hectares. The analysis of land suitability for tourism in relation to tsunami risk aims to assess the level of compatibility of a tourist area located in a tsunami-prone region. The environmental vulnerability parameters include elevation, land slope, coastal morphology, land use, distance from the coastline, and distance from rivers. Additionally, bathymetric data and tsunami run-up based on historical tsunami events in the southern coastal areas of Java Island are utilized to assess the extent and depth of tsunami inundation. In the analysis of tourism suitability based on tsunami disaster mitigation, the suitable tourism area is located in the eastern part of Sidoarjo Village and the entire Ploso Village. These areas fall into the high tsunami risk zone, but their tourism potential is also high due to the coastal location of tourist attractions

A brief history of tsunamis in the Vanuatu Arc

Abstract. The archipelagos of Vanuatu and the eastern Solomon Islands, scattered over 1500 km along the Vanuatu Arc, include dozens of inhabited volcanic islands exposed to many natural hazards that impact their populations more or less severely. Due to the location of these islands on a subduction interface known as the Vanuatu subduction zone, tsunamis triggered by earthquakes, volcanic eruptions, and landslides locally, regionally, and in the far field represent a permanent threat. If catalogues already list tsunamis that have occurred in the Vanuatu Arc, they were not exclusively focusing on this region. This study goes further in the listing of tsunamis reported and/or recorded in the Vanuatu Arc, analysing existing catalogues, historical documents, and sea-level data from the five coastal tide gauges located in Vanuatu at Port Vila (Efate), Luganville (Espiritu Santo), Litzlitz (Malekula), and Lenakel (Tanna) and in the eastern Solomon Islands province at Lata (Ndende). It allows the identification of 100 tsunamis since 1863, 15 of them showing wave amplitude and/or run-up height of more than 1 m and 8 between 0.3 and 1 m. While some tsunamis are known to have occurred in the past, information about the wave amplitude or potential run-up is sometime lost (15 events). Also, tsunamis reported in neighbouring islands like New Caledonia but not reported or recorded in the Vanuatu Arc are discussed, as well as debated events or events with no known origin(s).

Possible Mechanisms for Tsunami‐Like Surge Deposits Due To the Chicxulub Impact at the K‐Pg Boundary at the Tanis Site, North Dakota

AbstractAt Tanis, a unique bi‐directional sediment package occurs precisely at the Cretaceous‐Paleogene (K‐Pg) boundary, recording the first hours of the Paleogene in uncommonly fine temporal detail. The impact ejecta‐bearing sediment package was rapidly emplaced by two massive, ∼10‐m‐high, potentially impact‐triggered surges, that inundated a steep, deeply incised paleo river valley from the direction of the contemporaneous Western Interior Seaway (WIS). Intermingling of fresh‐ and salt‐water fossils at Tanis, coeval brackish water indicators in the nearby region, and historical tsunami observations, suggest that the WIS paleoshoreline was nearby Tanis at K‐Pg time. The interpreted timing for deposition (including ejecta infall) of ∼1–2‐hr immediately post‐impact precludes a direct tsunami from the Chicxulub impact site, which would have required much more than 10 hr to reach Tanis. Seismic waves from the Mw ∼ 11 Chicxulub earthquake, arriving just minutes post‐impact, might have triggered the surge, for example, via seismic excitation of large water waves in the WIS, as proposed by DePalma et al. (2019, https://doi.org/10.1073/pnas.1817407116). Here, we explore this mechanism via a simple mathematical model of seismic excitation and propagation of a water wave into a shallow river and upstream. Matching the observations implies a relatively long source process time of many minutes, such as generated by Chicxulub crater rebound processes, in order to explain sufficient upriver amplitudes and advective transport. Atmospheric waves due to the expanding Chicxulub ejecta curtain might have provided a smaller, secondary contribution during triggering. Thus, the mechanism(s) for the surges at Tanis are now better‐constrained, yet remain incompletely resolved.

Tsunami deposits highlight high-magnitude earthquake potential in the Guerrero seismic gap Mexico

Globally, the largest tsunamigenic earthquakes have occurred along subduction zones. Devastating events exceeding magnitude 9, such as those in Chile, Sumatra, and Japan, struck in regions lacking instrumental records of similar events. Despite the absence of such events along the 1000-kilometer-long Mexican subduction zone, historical and geologic evidence suggests the occurrence of a magnitude 8.6 tsunamigenic earthquake. However, the Guerrero seismic gap has not experienced a high-magnitude earthquake in over 100 years. Here we present results on analyses of sediment grain size, geochemistry, microfossils, magnetic properties, and radiometric and optical stimulated luminescence dating conducted along the Guerrero coast. We provide evidence of a 2000-year history of large tsunamis triggered by potentially large earthquakes. Numerical modeling supports our findings, indicating a magnitude >8 event around the year 1300 in the Guerrero seismic gap. This evidence underscores the importance of assessing earthquake and tsunami potential using long-term evidence and instrumental observations along subduction zones globally.

Scenario-based tsunami hazard assessment for Northeastern Adriatic coasts

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

Offshore evidence of historic and prehistoric tsunamis on the north shore of Tutuila (American Samoa)

Although research dealing with the geological evidence of past tsunamis has increased significantly in the last two decades, studies of tsunami deposits emplaced during the backwash phases are still underrepresented. Here, we provide the first investigation of tsunami backwash deposits all around an island (Tutuila Island, American Samoa), in the southwest of the Pacific Ring of Fire. We decipher the sedimentary record preserved offshore an open bay (Fagafue) and within a sheltered bay (Masefau) on the north shore of Tutuila. Backwash deposits of three historic tsunamis, namely the 2009 South Pacific, 1960 Valdivia and 1917 Tonga Trench tsunamis, were identified in sediment cores, based on sedimentological, geochemical and chronological data. Deposits were characterized by a geochemical terrestrial signature (Ti/Ca and K), while the grain size characteristics differed, being finer offshore the open bay and coarser within the sheltered bay. The 2009 South Pacific and the 1960 Valdivia tsunamis are recorded on both the north (Masefau and off Fagafue bays) and south (Pago Pago Bay) shores of Tutuila, providing the first correlation of tsunami backwash deposits all around an island. Furthermore, the present study presents the first geological evidence of backwash associated with a large 15–16th century tsunami, which also affected many parts of the South Pacific, as well as that of an older event between the 11th and 14th century. Studies of tsunami backwash deposits provide means to extend the geological record of these high energy events, due to the generally good preservation potential of the deposits.

Application of a subgrid-scale urban inundation model for a storm surge simulation: Case study of typhoon Haiyan

This study evaluated the individual drag force model (iDFM), a subgrid-scale model for simulating tsunami inundation in coastal urban areas. The iDFM was then applied to characterize Typhoon Haiyan-induced storm surge inundations in 2013. Using a post-typhoon survey dataset containing inundation depths at different survey points with inundation limits, the performance of iDFM was validated, and the results confirmed that iDFM accurately estimates the storm surge inundation depths but overestimates the limit of inundation. In addition, the results revealed that the iDFM flow velocity was a dominant factor, and the inclusion of buildings in the simulated affected the arrival of the leading edge of inundation. Furthermore, the reduction in flow velocity was sensitive to the subgrid-scale parameters, and the spatial distribution pattern of buildings located in the inundated area affected the relative difference in the maximum flow velocity with the regional roughness model. The inundation characteristics of the Typhoon Haiyan storm surge models were compared with a historical tsunami event. The inundation characteristics were similar and model differences were observed mainly in the fluid velocity and momentum flux rather than the inundation depth. However, the magnitudes of relative differences observed in Tacloban were larger for fluid velocity and momentum flux, respectively, than in the tsunami event. The effect of building drag on advection was also substantial in Tacloban due to the differences in the inflow mass and momentum fluxes.

Indonesian “tsunami-generation” in a nutshell: systematic literature review

Publications related to tsunami-generation phase hold 42.8% of all the publications over all tsunami hazard literatures in Indonesia. Corroborating the fact, tsunami-generation studies are also vital in determining the type of propagation and inundation that may appear in the surrounding coastal regions, which in practice, can also help determining disaster management specifics and risk reduction activities. A literature review regarding tsunami-generation has been done for those purpose by using our CARI! Knowledge Engine, which includes collections of both International and Indonesian journals within the scope of Indonesian locus context. This study unpacks publication trend, the most influential articles, top contributing journals, top main authors, top institutions, and dominant countries as well as the science mapping of tsunami-generation subjects. To gain deeper understanding, we also develop tsunami-generation research framework within the basis of tsunami generation force, time occurrence, monitoring, and measurement approach, as well as hazard analysis approach. From the review, an interesting peak of tsunami-generation publications has been shown in 2020 (39 publications), following the occurrence of several Indonesian major tsunamis in the previous decade and the globally impacting Aceh Tsunami (or the Indian Ocean Earthquake and Tsunami) in 2004. Among all the publications of tsunami-generation force, tsunamigenic earthquake has become the most studied topic (67.7% of all publications), while the most discussed atypical sources mainly come from volcanic eruption (46.67% of all atypical literatures) and submarine landslide (33.33% of all atypical literatures). In terms of tsunami-generation source, it is found that the Sunda Megathrust has been the most-discussed location, which is mentioned within 39 publications, followed by the Palu-Koro Fault with 18 publications and the Krakatau Volcano by 16 publications. Apart from the notice of significant difference between research of historical tsunami and paleotsunami (120:5 publications), some gaps also can be found when discussing the meteotsunami-generation mechanism in Indonesia and the Global Navigation Satellite System’s Total Electron Content (GNSS-TEC) method, which, although proven beneficial for the development of tsunami early warning system, accuracy is still the main issue in capturing tsunami signals and positioning actual source location of tsunami. These were some highlighted limitations that arise in our process to understand tsunami-generation mechanisms and the exploitations of the knowledge. Therefore, future studies specifically within these areas are further encouraged.

Marine inundation history during the last 3000 years at Lake Kogare-ike, a coastal lake on the Pacific coast of central Japan

Sediment cores collected at Lake Kogare-ike, a coastal lake on the Pacific coast of central Japan, record the marine inundation history during the last 3000 years. The sediments consist mainly of organic mud, sand, gravel, inorganic mud, and volcanic ash, and inundation events were recognized as 19 event deposits (E1–E19, from top to bottom) interbedded with the organic mud. Visual observation by naked eyes and X-ray computed tomography (CT) images identified 16 event deposits based on quantitative and qualitative changes in sand contents and changes in the textures and colors of the sediment samples (E1–E3, E5, E6, E8, E9, and E11–E19). The other three event deposits (E4, E7, and E10) were identified only on the CT images as layers with higher radiodensity than the underlying and overlying organic mud layers. The sedimentary features, the spatial bias of the event deposits toward seaward areas, the diatom assemblages, and the frequency of inundation events suggest that 13 (E1–E10 and E12–E14) of the 19 event deposits were formed by tsunamis or extraordinary storms. To constrain the depositional ages of the event deposits, Bayesian age–depth models were constructed based on radiocarbon dating of plant macrofossils and concentrated fossil pollen and the 137Cs profile. The depositional ages of the event deposits indicate that five or possibly six event deposits can be correlated with historical tsunamis along the Nankai Trough: E2, either of E3 or E4, E5, E7, and E9 correspond to the 1707 CE Hoei, the 1605 CE Keicho, the 1498 CE Meio, the 1096 CE Eicho, and the 684 CE Hakuho tsunamis, respectively. E1 was possibly formed by the 1944 CE Showa-Tonankai tsunami, the 1854 Ansei–Tokai tsunami, the 1959 Isewan typhoon, or a combination of two or all three events.

Sedimentary evidence of tsunamis in New Caledonia, southwest Pacific

This study aims to identify tsunamis in the coastal sedimentary archives of New Caledonia (Grande Terre and the Loyalty Islands) in the southwest Pacific, to extend a relatively short historical tsunami record (150 years), and to bring more constraints on the frequency of the main tsunamigenic earthquakes in the region. Using a combination of sedimentary and geochemical approaches on sediment core samples, we document three types of deposits related to marine inundation: (1) bioclastic sand layers; (2) crypto-deposits with a marine chemical signature; and (3) accumulations of rounded pumice lapilli. Most of the sampling sites being located outside the morpho-dynamic impact zone of the cyclones, a tsunami origin is preferred. The spatial distribution of the deposits suggests tsunami runups exceeding 2.5 m a.s.l. on the northeastern coast of Grande Terre, 6 m on the eastern coast of Maré Island, and 10 m on the northeastern coast of Lifou Island. Finally, at least six tsunamis were preserved in the sedimentary record: one event soon after 1000 BCE, two events during the first millennium CE, and at least three events during the last millenium (including a 15th century tsunami, the 28 March 1875 tsunami, and a tsunami possibly related to the 1729 earthquake in Vanuatu).

Tsunami Wave Characteristics from the 1674 Ambon Earthquake Event Based on Landslide Scenarios

This study focuses on understanding the historical tsunami events in Eastern Indonesia, specifically the Banda Sea region, by extracting information from the limited and challenging-to-interpret historical records. The oldest detailed account of a tsunami in Indonesia dates back to 1674, documented in the book Waerachtigh Verhael Van de Schlickelijcke Aerdbebinge by Rumphius. The study aims to comprehend the primary source of the tsunami and analyze its characteristics to facilitate future tsunami risk reduction. The methodology includes collecting topography and bathymetry data, conducting landslide scenario analysis, employing a two-layer wave propagation model, and performing spectral analysis. The study utilizes comprehensive datasets, investigates potential landslide scenarios, simulates tsunami propagation, and analyzes frequency characteristics using the fast Fourier transform. The 1674 event yielded a runup height of approximately 50–100 m, whereas this study underestimated the actual runup. To illustrate the tsunami wave along the bay’s coastline, a Hovmöller diagram was employed. By analyzing the Hovmöller diagram, the power spectral density was computed, revealing five prominent period bands: 6.96, 5.16, 4.1, 3.75, and 3.36 min. The integration of these components provides a rigorous approach to understanding tsunami dynamics and enhancing risk assessment and mitigation in the study area.

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

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

Modelling Tsunami Based On History In North Of Buru Island, Molluccas

The existence of the islands in Maluku is very vulnerable to the danger of a tsunami-generating earthquake, because of their location to faults or faults. The purpose of this study was to analyze the height and propagation time of the tsunami waves in coastal areas in Maluku such as Buru Island, Ambelau Island, Manipa Island, Kelang Island. One of the historical tsunami events in Maluku on January 28, 2004, with a magnitude 6.6 earthquake with a depth of 16.8 km, is a case study parameter for create a tsunami wave propagation model for the purposes of tsunami disaster mitigation in affected coastal areas. The tsunami propagation model in this study uses SitProS modeling to analyze the height and propagation of tsunami waves on the coasts of the islands in Maluku. The bathymetry data used was obtained from the ETOPO site, while the fault parameters were obtained from the BMKG site where the sizes of the strike, dip and slip angles were 194o, 84o and -136o respectively. The result of modeled tsunami height ranges from 0.09 – 0.3 meters with a propagation time up to 13 meters on Ambon Island. Buru Island is an area which close to the epicenter of the earthquake so the waves arrived in the 3rd minute with the maximum height until 0.3 meters.

Tsunami early warning system using offshore tsunameters in Peru

Earthquakes occurring in the Peru-Chile Trench can trigger tsunamis that damage the Peruvian coast. The Directorate of Hydrography and Navigation plans to install three offshore tsunameters in 2023. We propose a tsunami early warning system that uses these tsunameters and targets the Lima Metropolitan Area (LMA), based on the inversion of the initial sea-surface distribution and the superposition of Green's function. Four coastal stations were selected to test the system using historical tsunami events. The forecasts made 15 min after the earthquake had accuracies of 77.0% and 19.4% for the 1966 Huacho and 2001 Camana earthquakes, respectively, whereas the forecasts made 30 min after the earthquake had accuracies of 82.4% and 98.9% for the 1966 and 2001 events, respectively. These results confirmed that the three planned offshore tsunameters will be reliable for making tsunami early warning for the LMA. Moreover, we tested the system using six and ten offshore tsunameters. An increase in the number of offshore tsunameters generally improved the forecast accuracy, but the improvement was not significant. This study is the first to investigate a tsunami early warning algorithm using offshore tsunameters for the Peruvian coast. The results are helpful in mitigating coastal hazards at a reasonable cost.

Probabilistic Tsunami Risk Assessment from Incomplete and Uncertain Historical Impact Records: Mediterranean and Connected Seas

Tsunami risk is considered as the probability of a particular coastline being struck by a tsunami that may cause a certain level of impact (destructiveness). The impact metric of a tsunami is expressed in terms of tsunami intensity values, K, assigned on a 12-degree scale. To calculate tsunami risk we are based on the tsunami history of the region codified in tsunami catalogues. The probabilistic model adopted was used successfully for hazard assessment of earthquakes (Kijko et al. in Bull Seismol Soc Am 79:645–654, 2016) and of tsunamis (Smit et al. in Environmetrics 30:e2566, 2019) by considering seismic magnitude and tsunami height as metrics of the respective hazards. In this model, instead of hazard metrics we inserted risk metric, i.e. wave impact in terms of intensity values. The procedure allows utilization of the entire data set consisting not only from the complete (recent) part of tsunami catalogue but also from the highly incomplete and uncertain historical part of the catalogue. Risk is assessed in terms of probabilities of exceedance and return periods of certain intensity values in specific time frames. We applied the model using catalogues for the Mediterranean and connected seas. Sensitivity analysis showed that using complete data sets generally provided more realistic results than using entire data sets. Results indicated that the risk level depends on the seismicity level and not on the size of individual ocean basin. The highest tsunami risk level was found in the eastern Mediterranean (EM), with a significantly lower risk in the western Mediterranean (WM). In the Marmara Sea (MS), the tsunami risk was low, and the lowest was in the Black Sea (BS). The risk in the small Corinth Gulf (CG, Central Greece) was comparable to that of WM. The return period of damaging tsunamis (i.e. K ≥ 7) was 22 years in the entire Mediterranean basin and 31, 118, 135, 424, and 1660 years in the EM, WM, CG, MS, and BS basins, respectively.

On the open sea propagation of two-dimensional rotational water waves generated by a moving bed

We study the propagation of two-dimensional tsunami waves triggered by a seaquake in the open sea in the presence of underlying wind-generated currents, corresponding to background flows of constant vorticity. A suitable scaling of the governing equations introduces dimensionless parameters, of particular interest being the setting of linear waves that only depend on the vertical movement of the sea bed. We use Fourier analysis methods to extract formulae for the function f which describes the vertical displacement of the water's free surface. We show that the results are particularly useful in the physically relevant shallow-water regime: in the irrotational case the predictions fit well with the observed behaviour of some historical tsunamis. In other situations, the stationary-phase principle gives insight into the asymptotic behaviour of f.