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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 recent paroxysmal crisis occurring on the island of Stromboli (Tyrrhenian Sea, Italy), manifesting into two main events during summer 2019 (3rd July and 28th August), renovated the attention on the possibility of tsunami generation induced by volcanic activity. The Stromboli edifice is characterized by the Sciara del Fuoco scar on its north-western flank channeling most of the material ejected from the crater to the sea.In this area, in December 2002, two landslides (the first submarine, the second subaerial) triggered large waves affecting the whole coast of the island, causing severe damages but fortunately no casualties, due to the non-touristic period. The tsunami rapidly dissipated with distance, being observed in Panarea (20 km south-east of Stromboli), as is typical of non-seismic tsunamigenic sources. A similar occurrence during summer would have resulted into dramatic consequences, especially along the Stromboli coasts.In this study, the tsunamigenic potential associated with destabilized mass along Stromboli flanks is evaluated by means of numerical, in-house developed, codes with the aim of providing insights on the tsunami hazard along the coasts of Stromboli, of the surrounding Aeolian archipelago and in general in a larger domain covering the southern coasts of Tyrrhenian Sea as well.

A major tsunami-like event, locally known as ‘marrobbio’, impacted the southwestern coast of Sicily on 25–26 June 2014. The event was part of a chain of hazardous episodes in the Mediterranean and Black seas during the last week of June 2014 resulting from an anomalous atmospheric system (“tumultuous atmosphere”) propagating eastward over the region. The synoptic patterns and vertical structure of the atmosphere over Sicily at the time of the event indicate that atmospheric wave ducting was responsible for the generation of tsunamigenic air pressure disturbances that produced especially high sea level responses (“meteotsunamis”) at certain sites along the Sicilian coast. The strongest sea level oscillations were observed at Mazara del Vallo, where a 1-m meteotsunami bore, propagating upstream in the Mazaro River, was generated. The combined effects of external resonance (Proudman resonance on the western Sicilian shelf) and internal resonant conditions (bathymetric and topographic characteristics of specific sites) were found to be the key factors that caused the meteotsunami (marrobbio phenomenon) on the coast of Sicily and the meteobore at Mazara del Vallo.

Slides along continental margins represent a considerable source of hazard, especially when occurring in shallow water close to a densely populated coast. Among the known landslide–tsunamis affecting harbors or coastal infrastructures, the 1977 event that hit the harbor of Gioia Tauro (SE Tyrrhenian Sea, Italy) is one of the less studied. According to historical reports, 5 m waves hit the western dock, provoking relevant damages on port facilities. Post-event bathymetric surveys found a lack of mass of more than 5 million m3 at the head of the Gioia Tauro canyon, that starts just outside the harbor. After having considered two possible sliding bodies, the respective landslide motion and generated tsunami are calculated here through numerical in-house developed numerical codes, in order to assess their effects on the coast and validate the hypothesis of a landslide source for the 1977 event. Tsunami features inside the harbor basin are characterized as well, evidencing the importance of assessing the consequence of such small-scale events, not involving large areas but posing a relevant threat for coastal communities and infrastructures.

Central America (CA), from Guatemala to Panama, has been struck by at least 52 tsunamis between 1539 and 2013, and in the extended region from Mexico to northern Peru (denoted as ECA, Extended Central America in this paper) the number of recorded tsunamis in the same time span is more than 100, most of which were triggered by earthquakes located in the Middle American Trench that runs parallel to the Pacific coast. The most severe event in the catalogue is the tsunami that occurred on 2 September 1992 off Nicaragua, with run-up measured in the range of 5–10 m in several places along the Nicaraguan coast. The aim of this paper is to assess the tsunami hazard on the Pacific coast of this extended region, and to this purpose a hybrid probabilistic-deterministic analysis is performed, that is adequate for tsunamis generated by earthquakes. More specifically, the probabilistic approach is used to compute the Gutenberg–Richter coefficients of the main seismic tsunamigenic zones of the area and to estimate the annual rate of occurrence of tsunamigenic earthquakes and their corresponding return period. The output of the probabilistic part of the method is taken as input by the deterministic part, which is applied to calculate the tsunami run-up distribution along the coast.

Eighteen papers are included in Volume 1 of a PAGEOPH topical issue Tsunamis in the World Ocean: Past, Present, and Future. These papers are briefly introduced. They are grouped into three categories: case studies of earthquake-generated tsunamis; tsunami forecast and hazard assessments; and theoretical and computational modeling of tsunami generation, propagation, and coastal behavior. Most of the papers were presented at the 24th International Tsunami Symposium held 14–16 July 2009 in Novosibirsk, Russia, and reflect the current state of tsunami science.

The island of Ischia, Gulf of Naples, Italy, like many other volcanic islands is affected by mass failures, that are mainly related to secondary volcanic processes such as slope steepening and seismic shaking. The block resurgence of its main relief, Mount Epomeo, has been recognised to contribute cyclically to mass instability and cause landslides, that occasionally may reach the sea and start tsunamis. In this work we explore the consequences of the Ischia Debris Avalanche (IDA), a flank collapse that occurred in historical times, and involved the whole Mount Epomeo edifice including its submarine portion, and that may have caused gigantic sea waves affecting all the coasts of Ischia and of the Gulf of Naples. The IDA and the generated tsunami have been taken as the worst-case scenario for the occurrence of a new tsunami in the area. They have been simulated through numerical codes developed and maintained by the University of Bologna. The simulation shows that the IDA-induced tsunami attacks severely all the coasts of the Gulf of Naples with the highest waves obtained for the island of Ischia, the island of Capri and the peninsula of Sorrento. The propagation pattern of the IDA tsunami can be used to get hints on the impact that such an event may have had on early populations habiting Gulf of Naples, but also to get clues on the area that could be most severely hit by a tsunami generated by a smaller-scale landslide that may occur in the same source zone.

The M W = 7.4 earthquake that affected the northwestern part of Turkey on August 17, 1999, and in particular the gulf of Izmit, had dramatic consequences also as regards tsunami generation. The main cause of the earthquake was a dextral strike-slip rupture that took place along different segments of the western part of the North Anatolian Fault (WNAF). The rupture process involved not only a number of distinct strike-slip fault segments, but also dip-slip ancillary faults, connecting the main transcurrent segments. The general picture was further complicated by the occurrence of subsidence and liquefaction phenomena, especially along the coasts of the Izmit bay and in the Sapanca Lake. Tsunami effects were observed and measured during post-event surveys in several places along both the northern and the southern coasts of the bay. The run-up heights in most places were reported to lie in the interval 1–3 m: but in the small town of Degirmendere, where a local slump occurred carrying underwater buildings and gardens of the waterfront sector, eyewitnesses reported water waves higher than 15 m. The purpose of this work is to investigate on the causes of the tsunami by means of numerical simulations of the water waves. We show that the tsunami was a complex event consisting at least of the combination of a regional event due to tectonic causes and of a local event associated with the mass failure. As to the first, we are able to demonstrate that the observed tsunami cannot be explained only in terms of the sea bottom dislocation produced by the main right-lateral dislocation, but that the prominent contribution comes from the displacement associated with the secondary shallow normal faults. Furthermore, the large waves and effects seen in Degirmendere can be explained as the consequence of the slump. By means of a stability analysis based on an original method making use of the limit equilibrium concept, we show that the slump was highly stable before the earthquake and that it was triggered by seismic waves. Simulation of the tsunami induced by the slump was carried out by a two-step numerical code that computes the landslide motion first, and then the generated water wave propagation. It is shown that the computed local tsunami matches the experimental data.

This paper outlines the main contributions to the definition and evaluation of tsunami hazard and risk resulting from studies undertaken in Italy in recent years and emphasises that adopting characteristic cases or scenarios is a very useful and advantageous technique. Three main cases are given as valuable examples, that is the 1627 Gargano tsunami, the 1693 eastern Sicily tsunami and the 1908 Messina Straits tsunami, since: (1) they characterise three distinct tsunamigenic regions; (2) they are instances of destructive events; and (3) they have been extensively studied in the last decade. The paper elucidates the state-of-the-art of the research on these events, clarifies the chief points of agreement and disagreement among scientists, and illustrates the main issues that are to be addressed by future research to provide reliable assessment of tsunami risk and to implement efficient countermeasures to defend the life of people, coastal structures and the coastal environment against the attacks of tsunamis.

The M w = 9.1 mega-thrust Sumatra–Andaman earthquake that occurred on December 26, 2004, was followed by a devastating tsunami that killed hundreds of thousands of people and caused catastrophic effects on human settlements and environments along many coasts of the Indian Ocean, where even countries very far from the source were affected. One of these cases is represented by the Republic of Seychelles, where the tsunami reached the region about 7 h after the earthquake and produced relevant damages, despite the country was more than 4,500 km far from the seismic source. In the present work, we present and discuss a study of the 2004 Sumatra tsunami by means of numerical simulations with the attention focused on the effects observed at the Seychelles Archipelago, a region never previously investigated with this approach. The case is interesting since these islands lay on a very shallow oceanic platform with steep slopes so as the ocean depth changes from thousands to few tens of meters over short distances, with significant effects on the tsunami propagation features: the waves are strongly refracted by the oceanic platform and the tsunami signal is modified by the introduction of additional frequencies. The study is used also to validate the UBO-TSUFD numerical code on a real tsunami event in the far field, and the results are compared with the available observations, i.e., the sea level time series recorded at the Pointe La Rue station, Mahe Island, and run-up measurements and inundation lines surveyed few weeks after the tsunami at Praslin Island, where the tsunami hit during low tide. Synthetic results are found in good agreement with observations, even though some of the observations remain not fully solved. Moreover, simulations have been run in high-tide condition since the 2004 Sumatra tsunami hitting at high tide can be taken as the worst-case scenario for the Seychelles islands and used for tsunami hazard and risk assessments.

Underwater mass movements along continental margins constitute a relevant threat for coastal communities. In the Mediterranean Sea this issue is particularly critical, both for the concentration of potential sources and for the density of population living along the coast. One of the biggest event recently mapped by submarine geophysical surveys, named BIG’95, is located in the Balearic Sea, between the homonymous islands and the Eastern coast of Spain: it occurred around 11 kyrs BP, involving a volume of around 26 km3 over an area of 2,200 km2, from 200 m depth down to 1,600 m and over: the looser fraction of the mass was driven along the Valencia Channel, NE-ward, more than 110 km far from the source area. The BIG’95 event is here simulated through numerical codes, adopting some reasonable simplifications on the slide morphology and dynamics. The tsunamigenic impulse is then evaluated and the propagation of the wave simulated over a computational domain covering the Western Mediterranean Sea. Results show that an event of these characteristics can generate catastrophic tsunami along the coasts of the Balearic Sea, reaching also North Africa, Corsica and Sardinia coasts with relevant waves.

On July 12th, 1977, waves 5 m high hit the harbour of Gioia Tauro, provoking relevant damages on facilities and infrastructures, but fortunately no casualties. The source was supposed to be a submarine mass failure, ranging 5 million m3 and occurring in very shallow water at the heads of a canyon just in front of the port. The sliding mass cut a cable at 600 m depth, meaning that it travelled more than 15 km far from the source. In this work we reconstruct the hypothesized mass failure, compute the slide dynamics and simulate the generated tsunami through numerical modelling. The results obtained fit well with the observations, strengthening the hypothesis of such a landslide as the source for the 1977 tsunami. This event can be considered as paradigmatic of a category of coastal hazards: small submarine landslides occurring close to populated coasts may pose considerable risk, even if only at a local scale.

Papadopoulos, Gerassimos ... et. al.-- 29 pages, 14 figures, 2 tables, The origin of tsunamis in the Mediterranean region and its connected seas, including the Marmara Sea, the Black Sea and the SW Iberian Margin in the NE Atlantic Ocean, is reviewed within the geological and seismotectonic settings of the region. A variety of historical documentary sources combined with evidence from onshore and offshore geological signatures, geomorphological imprints, observations from selected coastal archeological sites, as well as instrumental records, eyewitnesses accounts and pictorial material, clearly indicate that tsunami sources both seismic and non-seismic (e.g. volcanism, landslides) can be found in all the seas of the region with a variable tsunamigenic potential. Local, regional and basin-wide tsunamis have been documented. An improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented. From west to east, the most important tsunamigenic zones are situated offshore SW Iberia, in the North Algerian margin, in the Tyrrhenian Calabria and Messina Straits, in the western and eastern segments of the Hellenic Arc, in the Corinth Gulf of Central Greece, in the Levantine Sea offshore the Dead Sea Transform Fault and in the eastern side of the Marmara Sea. Important historical examples, including destructive tsunamis associated with large earthquakes, are presented. The mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency (1/96. years) is observed in the east Mediterranean basin. For most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co-seismic slip, by earthquake-triggered submarine landslides or by a combination of both mechanisms. In pre-historical times, submarine volcanic eruptions (i.e. caldera collapse, massive pyroclastic flows, volcanogenic landslides) and large submarine landslides caused important tsunamis although little is known about their source mechanisms. We conclude that further investigation of the tsunami generation mechanisms is of primary importance in the Mediterranean region. Inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent, well-documented, aseismic landslide tsunamis (e.g., 1963 Corinth Gulf, 1979 CÔte d'Azur, 1999 Izmit Bay, 2002 Stromboli volcano). Since the tsunami generation mechanisms are controlled by a variety of factors, and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action, future interdisciplinary research efforts on past tsunamis are needed. © 2014 Elsevier B.V., The National Observatory of Athens, the University of Bologna, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), the Hellenic Center for Marine Research, the Middle East Technical University as well as the Universidad de Cantabria acknowledge co-funding from the EU-FP6 TRANSFER research project, 2006–2009, contract n. 037058. The National Observatory of Athens, the University of Bologna and the Universidad de Cantabria are co-funded by the DG ECHO of EU, project NEARTOWARN, 2012–2013, contract n. 230301/2011/614039/SUB/A5. Barcelona-CSI acknowledges that this work has been carried out within Grups de Recerca de la Generalitat de Catalunya B-CSI (2009 SGR 146) and the support of the Spanish Ministry of Science and Innovation (MICINN) through National Projects EVENT (CGL2006-12861-C02-02), MEDOC (CTM2007-66179-C02-02/MAR), POSEIDON (CTM2010-21569), SHAKE (CGL2011-30005-C02-02), and HADES (CTM2011-30400-C02-01 and CTM2011-30400-C02-02), Complementary Action NEAREST-SEIS (CGL2006-27098-E/BTE), the EU Programme “Global Change and Ecosystems” contract n. 037110 (NEAREST), ESF TopoEurope TOPOMED project (CGL2008-03474-E/BTE) and the IGCP-585. Τhe Istituto Nazionale di Geofisica e Vulcanologia (INGV) acknowledges the Italian Department of Civil Protection for funding a project in the frame of the 2007–2009 agreement

The 1693 earthquake was a disastrous event affecting eastern Sicily, southern Italy, where it caused over 60,000 victims and total destruction of several villages and towns in the districts of Siracusa, Ragusa, and Catania. The earthquake was followed by a tsunami that struck the Ionian coasts of Sicily and the Messina Strait and was probably observed even in the Aeolian Islands. Historical documents on sea waves and flooding, though not abundant, allow us to form a picture of the tsunami first attack and inundation. The first water movement all along the Sicilian coastline was a strong sea withdrawal, followed by a violent sea return and coastal flooding. The main purpose of this research is to put constraints on the focal mechanism of this earthquake on the basis of the available documents on the tsunami (1) by simulating tsunami from different possible sources via numerical modeling based on finite element technique and shallow water approximation and (2) by choosing the source best fitting the tsunami data as the most plausible cause for this tsunami. The relevance of this study should also be evaluated in light of the circumstance that no certain indication on the earthquake fault can be deduced from the available macroseismic data alone. Solving the source problem for this event, one of the largest occurring in southeastern Sicily in historical times, is a significant contribution to understanding the seismotectonic regime of the region and to assessing the related earthquake and tsunami hazard/risk with implications on mitigation policies.

The paper is a report of the field campaign undertaken by an international team (Italian, French and Indonesian) a few weeks after the occurrence of a tsunami invading the south-eastern coast of Java (Indonesia) and it complements the results of a concurrent field survey by Asian and USA researchers. The tsunamigenic earthquake occurred on 3 of June 1994 in the Indian Ocean about 200 km south of Java. The tsunami caused severe damage and claimed many victims in some coastal villages. The main purpose of the survey was to measure the inundation and the runup values as well as to ascertain the possible morphological changes caused by the wave attacks. Attention was particularly focussed on the most affected districts, that is Lumajang, Jember and Banyuwangi in Java, although also the districts of Negera, Tebanan and Denpasar in Bali were examined. The most severe damage was observed in the Banyuwangi district, where the villages of Rajekwesi, Pancer and Lampon were almost completely levelled by the violent waves. Most places were hit by three significant waves with documented wave height often exceeding 5 m. The maximum runup value (9.50 m) was measured at Rajekwesi, where also the most impressive erosion phenomena could be found. In contrast, only in one place of the neighbouring island of Bali was there a slight tsunami, the rest of the island being practically unaffected.

Finite‐element methods are often used to compute the evolution of tsunami waves over a grid suitably adapted to the selected basin. In this article it is shown that the finite‐element space discretization of the shallow‐water wave equations leads to a set of differential equations that are first order in time, and that, after linearization, admit a solution in terms of a linear operator we call the wave propagator. The initial perturbation is decomposed over the basis of the wave propagator eigenvectors, modified according to factors suitably depending on time and eventually synthesized as a superposition of the grid eigenmodes. The properties of the solution can therefore be analyzed in terms of the spectral components of the initial fields and of the spectral properties of the wave propagator. It is shown that a wave propagator can be defined even when the problem is constrained by means of the conditions imposed on the grid boundaries, which is indeed what occurs in all practical applications. Free and...

Gargano is a small mountainous promontory protruding into the Southern Adriatic and, from a structural point of view, it is part of the Apulia foreland. Deformative structures, both inland and offshore the promontory, are quite common and can partially be associated with a substantial Quaternary uplifting. Seismogenically this area is well known, because several historical strong earthquakes have been reported to occur here and recent important seismic sequences have been recorded. This paper is a contribution to evaluate the seismogenic as well as the tsunamigenic potential of this region. Particular attention has been given to study the major events, some of which were able to produce tsunamis. The epicenter location of some of these earthquakes computed solely on the basis of macroseismic data would point to focal regions on land, but this is questionable if tsunami generation is taken into account. As regards the tsunamigenic potential, statistical analysis is used to evaluate the local geographical distribution of expected tsunamis and the mean return periods. It is found that large events are expected on average every 228 years, while a tsunami of any size is generated every about 84 years, which is in good agreement with the experimental observations.

A theoretical model of tsunami generation and propagation near an oceanic island is developed in this paper. The solution is computed by means of a method that is basically analytical and that synthesizes waveforms as a superposition of normal modes whose evolution is governed by the linearized shallow‐water equations. Sea‐bottom deformations are computed analytically via the classic dislocation theory applicable to plane faults with uniform slip. Initial sea‐surface elevations are assumed to be equal to floor displacements. The ocean basin circling the islands is supposed to have a depth depending only upon the distance from the island center. Tsunami propagation is computed in the whole basin with particular attention to the wave invading the island coasts. It is seen that a typical open‐ocean radiation pattern combines with diffracted wavefronts and wavefronts progressing around the island that tend to persist for a longer time after the first tsunami attack. These local island waves are particularly i...

The southern Adriatic basin is the current foredeep of the Albanide fold-and-thrust belt that runs along the eastern boundary of the Adriatic basin and partly owes its remarkable water depth, deeper than 1,000 m, to the Mesozoic palaeogeography of the region. The eastern slope of the southern Adriatic basin is characterized by a thick stack of sedimentary prograding units, fed by sediments coming from the adjacent fold-and-thrust belt, which is still seismically active (e. g. 1979 Montenegro, M = 6. 8). This slope presents extensive evidence of large-scale mass wasting throughout its Quaternary evolution and appears as a destructive slope system affected by progressive retreat. A submarine slide located along the eastern slope of the southern Adriatic basin has been recently characterized with good detail. The slide is of relatively small volume (0. 031 km3) and shows a limited displacement, without major internal disruption. The small volume of the landslide combined with its relatively large water depth (headscarp at about 560 m and deposit at 700 m) result in a limited tsunamigenic potential, that has been assessed numerically by means of a Lagrangian block model as regards the slide motion and through a shallow-water finite-difference code for the tsunami waves propagation. Despite the almost negligible tsunami effects, the studied landslide can be taken as a lower case limit for other events along the scarp, and the observed features concerning the generated wave and its impact on the coast can be considered valid also for bigger events.

The paper examines the possibility that tsunami event recorded in the western Black Sea on 7 May 2007 was triggered by a traveling atmospheric disturbance. As meteotsunamis are favored by specific synoptic conditions, we inspected available ground and sounding observations, European Centre for Medium‐Range Weather Forecasts reanalysis fields, and satellite‐based products and compared them to the documented Mediterranean meteotsunamis. We found an atmospheric disturbance traveling toward 30° (NNE) with amplitude of 2–3 hPa and propagation speed of about 16 m/s, passing through few tens of kilometers wide pathway over the region affected by the tsunami. This disturbance occurred in the lower troposphere, but it was capped by instable convective cell that preserved gravity disturbance's coherence over a region at least 150 km long. An ocean modeling study showed that such a disturbance is capable of generating large tsunami waves and strong currents over the shallow regions, following the observations over the region where maximum sea level oscillations have been documented. Therefore, this event has a potential to be classified as a meteotsunami, the first of such kind in the Black Sea.

This paper describes an extraordinary tsunami-like event that occurred on 21 June 1978 that encompassed the middle and south Adriatic Sea. The flood had its culmination in Vela Luka, where a maximum wave height of 6 m was reported. This paper contains a detailed description of the event as seen by eyewitnesses, its outreach along both the eastern and western coasts, and the aftermath and recovery activities in Vela Luka. All available records have been collected and analysed to detect the source and the generating mechanism of the long ocean waves. Seismic generation is fully excluded from the consideration, while a submarine landslide seems rather unrealistic as it does not explain the characteristics of the measured ocean waves. Therefore, the source of the event was presumably in the atmosphere, where a travelling disturbance was detected that had the capability to resonantly transfer energy to the ocean via the Proudman resonance mechanism. Although these data prove the proposed mechanism, the final confirmation for such a scenario should come from a process-oriented numerical modelling study.

In the Mediterranean Sea, tsunamigenic sources may be found in several areas in the belt running from Gibraltar up to the Black Sea, but they are concentrated mainly around Italy and Greece. Most o...

In this work we present the result of a study aimed at examining the Italian earthquake sequences that occurred in the area of the central Adriatic sea with the purpose of understanding whether some of them were accompanied by tsunami effects. The motivation for this research was the update and enrichment of the Italian Tsunami Catalogue. The result was that evidence was found for two new cases of earthquake-induced tsunamis: these are the August 1916 Rimini and the October 1930 Ancona events. The bulk of the present research consisted in collecting all the available data on the earthquakes that affected the selected area in the past century and in identifying those potentially capable of generating tsunamis. During the study all the available material was gathered, which includes specific monographs and scientific papers, articles available in contemporary chronicles and in local and national newspapers. The final result of this research will improve our knowledge of the tsunamigenic activity of the central Adriatic sea and contribute to the assessment of the tsunami hazard and risk along these coasts, that especially in the peak season form one of the most densely populated areas of the Italian peninsula with flat and large beaches and water front resorts crowded of tourists.

The Aeolian Islands, located in the south Tyrrhenian Sea to the west of Calabria and to the north of Sicily, constitute the Aeolian Volcanic Arc, characterized by a relevant volcanic activity with an established tsunamigenic potential. According to the documentary sources that are available for the Aeolian tsunamis, and that cover unfortunately only about the last 100 years, Stromboli is responsible for the majority of the events. Some cases are also known to have occurred at the islands of Salina and Vulcano. In terms of intensities, the most destructive events are those originated by the Stromboli volcano, reported to have produced severe destruction to boats and houses, and to have even caused injuries and fatalities. In this work, we focus on the historical events, and discard the paleotsunami occurrences that were probably associated with the ascertained flank collapses of the volcanic cones. We also neglect the recent destructive tsunamis of 30 December 2002, which were caused by a series of mass failures at the Sciara del Fuoco, since observations and analyses are of such an amount that deserve to be illustrated in devoted papers. The bulk of the present research consisted in collecting all the available data on the historical cases (the first in order of time is the July 1916 Stromboli tsunami) with the purpose of casting more light on their generation mechanism and on their effects, and consequently of contributing to the studies on assessment of tsunami hazard and risk in the Aeolian Islands and in the southern Tyrrhenian sea.

Tsunamis are hazardous natural events that are generated by earthquakes, by mass impact in the sea waters and by volcanic eruptions. Most tsunami sources are in the Pacific, but tsunamis have repeatedly affected even the Italian coasts. This paper is devoted to tsunamis in southern Italy, but in the first part it also provides some basic elementary notions on tsunamis for all those readers who are not too familiar with these phenomena. One important concept to have in mind is that tsunamis can be catastrophic. An instance of great disaster is the Sanriku tsunami on 2 March 1933 that was generated by a submarine earthquake with magnitude Mw = 8.4 (Kanamori 1977) and Mt = 8.3 (Abe 1979) occurring in the Pacific some 300 km from the northern coast of Honshu, the main island of Japan. Waves larger than 20 m (29.3 m at Shirahama in Ryori Bay) devastated several coastal Japanese towns, killing more than 3 000 people. The same area was devastated by another catastrophic tsunami on 15 June 1896 (Mt= 8.6 according to Abe 1979) that originated in the same source region and hit the coast with waves that reached the maximum extraordinary height of 38.2 m at Shirahama, causing more than 25 000 deaths (Iida 1984).

[1] We investigate the perturbations introduced by the local topography on the coseismic displacement components induced by crustal seismic faults. The approach, proposed by Tinti and Armigliato [2002], is applicable to homogeneous two-dimensional domains with arbitrary topography of the free surface. It uses both analytical results, valid for homogeneous spaces and half-spaces bounded by a flat free surface (FFS), and a numerical code solving the equations of equilibrium of linear elasticity through a finite element (FE) scheme. A major characteristic of our “hybrid” method is that it allows for the correct representation of the displacement components in correspondence with the fault, which does not need to be explicitly introduced in the FE mesh. We show that, in the case of homogeneous domains, this makes our approach preferable to pure FE schemes. Our hybrid approach is here applied to two different disastrous events of the recent Italian seismic history, for which topography is expected to play an important role, namely the 6 May 1976 (MS = 6.5) Friuli and the 23 November 1980 (MS = 6.9) Irpinia-Basilicata earthquakes. For each event, we selected hypotheses for the parent fault proposed in the literature and compared the coseismic displacements computed through the widely used analytical models dealing with FFS and through our hybrid approach, accounting for the effect of realistic topographies. The most relevant effects are observed in the case of the Irpinia earthquake: depending on the profile chosen, the computed misfits can be as high as 19 and 13% for the horizontal and vertical displacements, respectively, with absolute differences up to 9 and 10 cm.

About 300 descriptions of tsunamis and similar phenomena are known for the Mediterranean Sea. One can conventionally single out the following zones of origin and manifestation of tsunamis in the region, based on the seismotectonic conditions (Fig. 1)

A tsunamigenic earthquake occurred on June 3, 1994 with a violent tsunami involving the south-eastern Java coasts (Indonesia). The results of the report of the field campaign undertaken by an international team (Italian, French and Indonesian) during June 22 to June 28, a few weeks after the tsunami occurrence, are described in this paper, integrating the data obtained by a concurrent survey carried out by Asian and USA researchers. During the survey the authors focused their attention on the most affected districts in Java and Bali islands, visiting many coastal villages in order to interview inhabitants, to analyze damage, and to measure tsunami heights and inundation. It was underlined that the earthquake occurred during the night and caused no damage, being felt only by a few people. About 30–40 minutes after the shock generally three waves attacked the coast with documented heights often exceeding 5 meters, causing the destruction of some villages and claiming more than 250 victims. In this paper the authors present the results of their investigations, describing in detail tsunami heights and inundation as well as destructive tsunami effects at coastal villages This paper complements a previous preliminary report on this disaster (Maramai and Tinti, 1996).

Tsunamis generated by volcanic eruptions are much less frequent than tsunamis produced by submarine earthquakes. In the Mediterranean Sea only 2 percent of the observed tsunamis were caused by volcanoes according to a recent study by Soloviev (1990). In Italy the percentage of events related to volcanic activity is distinctly higher than in any other country of the Mediterranean, which is expected since most of the European active volcanoes and volcanic areas may be found in southern Italy. Of the 21 cases of which some information is available, 11 were observed in the Campania coasts and are related to Vesuvius activity, 7 are due to volcanic activity in the Aeolian Islands some 50 km northwest of the Messina Straits, while the others are related to Etna and to volcanic activity in the Sicily Channel. The most significant of these tsunamis seems to be that occurred in December 1631 during the great Vesuvian eruption (16–18 December) that was observed in the entire Gulf of Naples from Ischia to Sorrento and that began with a remarkable water withdrawal of more than 1000 yards followed by waves invading the coasts deep inland. Most cases are small tsunamis observed as anomalous waves on the coasts and causing no victims. This paper is the first systematic attempt to analyse tsunamis generated by volcanic eruptions in Italy and to discuss the tsunamigenic potential of the Italian volcanic sources. Most of the attention is focussed on Vesuvius and the Campanian volcanic area, that will be thoroughly examined. A similarly deep investigation on the Aeolian Islands tsunamis is postponed to a following paper.

The problem of computing the static deformations and stresses produced by a point source in a homogeneous infinite medium was solved by Volterra [1907] in a closed analytical form at the beginning of this century. The similar problem of computing fields generated by point sources in a homogeneous half-space bounded by a free surface was later studied by Steketee [1958a,b] and several others [see Okada, 1985, 1992], who focused on point as well as on rectangular fault sources of interest in seismology. Here the model taken into account consists of two elastic half-spaces characterized by different elastic properties (rigidity modulus μ and Poisson coefficient v ) and separated by a planar interface: assuming that a point source is active in one half-space, static deformations and stresses generated by the source in the whole space are computed. The similar problem of two half-spaces welded together was solved by Heaton and Heaton [1989], but they imposed the simplifying constraint that both materials are Poissonian ( i.e., both have the same Poisson coefficient v=0.25). The present approach, which is based on the Galerkin vector method, is general and applicable to an arbitrary point source. In this paper the computations have been carried out explicitly only for the special case of a dislocation source having the form of a strike-slip double couple. The solution is provided in a closed analytical form by means of expressions involving the source descriptors (position and intensity) as well as the elastic parameters of the heterogeneous medium. The solutions have been illustrated and discussed with special attention given to the dependence of the displacement and stress components on the elastic parameters of the model. One interesting finding concerns the limiting case when the rigidity modulus of the half-space not containing the point source is equalized to zero. Although the solution in this half-space no longer makes sense, the solution in the other reduces exactly to the one computed for a half-space with a free surface, that is, to the solutions computed by Steketee [1958a] and Okada [1985] following an alternative approach.