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Soil flow is involved in many earth surface processes such as debris flows and landslides. It is a very challenging task to model this large deformational phenomenon because of the extreme change in material configurations and properties when soil flows. Most of the existing models require a two-dimensional (2D) simplification of actual systems, which are however three-dimensional (3D). To overcome this issue, we develop a novel 3D particle finite element method (PFEM) for direct simulation of complex soil flows in 3D space. Our PFEM model implemented in a fully implicit solution framework based on a generalised Hellinger–Reissner variational principle permits the use of a large time step without compromising the numerical stability. A mixed quadratic-linear element is used to avoid volumetric locking issues and ensure computational accuracy. The correctness and robustness of our 3D PFEM formulation for modelling large deformational soil flow problems are demonstrated by a series of benchmarks against analytical or independent numerical solutions. Our model can serve as an effective tool to support the assessment of catastrophic soil slope failures and subsequent runout behaviours., Acta Geotechnica, 17, ISSN:1861-1125, ISSN:1861-1133

The estimation of the slope (b-value) of the frequency magnitude distribution of earthquakes is based on a formula derived by Aki decades ago, assuming a continuous exponential distribution. However, as the magnitude is usually provided with a limited resolution, its distribution is not continuous but discrete. In the literature this problem was initially solved by an empirical correction (due to Utsu) to the minimum magnitude, and later by providing an exact formula such as that by Tinti and Mulargia, based on the geometric distribution theory. A recent paper by van der Elst showed that the b-value can be estimated also by considering the magnitude differences (which are proven to follow an exponential discrete Laplace distribution) and that in this case the estimator is more resilient to the incompleteness of the magnitude dataset. In this work we provide the complete theoretical formulation including i) the derivation of the means and standard deviations of the discrete exponential and Laplace distributions; ii) the estimators of the decay parameter of the discrete exponential and trimmed Laplace distributions; and iii) the corresponding formulas for the parameter b. We further deduce iv) the standard 1-sigma confidence limits for the estimated b. Moreover, we are able v) to quantify the error associated with the Utsu minimum-magnitude correction. We tested extensively such formulas on simulated synthetic datasets including complete catalogues as well as catalogues affected by a strong incompleteness degree such as aftershock sequences where the incompleteness is made to vary from one event to the next.

In this article, we propose a new solution scheme for modeling elastoplastic problems with stress wave propagation in dissipative media. The scheme is founded on a generalized Hellinger-Reissner (HR) variational principle. The principle renders the discretized boundary-value problem into an equivalent second-order cone programming (SOCP) problem that can be resolved in mathematical programming using the advanced optimization algorithm-the interior point method. In such a way, the developed method not only inherits admirable features of the SOCP-based finite element method in solving elastoplastic problems but also enables the enforcement of absorbing layers (i.e., Caughey absorbing layer), which is essential in modeling stress wave propagation problems, to absorb wave energy. The proposed scheme is validated via the comparison between analytical and numerical results for seismic wave propagation in dissipative media. Its application to elastoplastic dynamic problems with stress wave propagation is also illustrated to demonstrate its efficiency., International Journal for Numerical Methods in Engineering, 124 (15), ISSN:1097-0207, ISSN:0029-5981

The Calabrian and Hellenic subduction systems accommodate the African Eurasian plate convergence in the Mediterranean Sea and are the site of large earthquakes in the forearc region facing the northern African coasts. Some of the historical earthquakes were associated with the generation of tsunami waves affecting the entire Mediterranean basin. We investigated the submarine effects of the AD 365 Crete earthquake on the sedimentary records through the integrated analysis of geophysical data, turbidite deposits, and tsunami modelling. Seismic reflection images show that some turbidite beds are thick and marked by acoustic transparent layers at their top. Radiometric dating of the most recent of such mega-beds, the Homogenite/Augias turbidite (HAT), provide evidence for synchronous basin-wide sedimentation during a catastrophic event which has occurred in the time window of AD 364–415, consistent with the AD 365 Mw = 8.3–8.5 Crete earthquake/tsunamis. The HAT (up to 25m thick) contains components from different sources, implying remobilization of material from areas very far from the epicentre. Utilizing the expanded stratigraphy of the HAT and the heterogeneity of the sediment sources of the Mediterranean margins, we reconstructed the relative contribution of the Italian, Maltan and African margins to the turbidite deposition. Our sedimentological reconstructions combined with tsunami modelling suggest that the tsunami following the Crete earthquake produced giant turbidity currents along a front over 2000km long, from northern Africa to Italy. Our cores suggests that during the last 15,000 years, only two similar turbidites have been deposited in the deep basins, pointing to a large recurrence time of such extreme sedimentary events.

This paper presents the failure analysis of layered clayey slopes with emphasis on the combined effect of the clay’s weakening behavior and the seismic loading using the particle finite element method (PFEM). Diverse failure mechanisms have been disclosed via the PFEM modelling when the strain-weakening behavior of clay is concerned. In contrast to a single layered slope exhibiting either a shallow or a deep failure mode, a layered slope may undergo both failure modes with a time interval in between. Seismic loadings also enlarge the scale of slope failure in clays with weakening behavior. The failure of a real layered slope (i.e. the 1988 Saint-Adelphe landslide, Canada) triggered by the Saguenay earthquake is also studied in this paper. The simulation results reveal that the choice of the strain-softening value controls the slip surface of the landslide and the amplification effect is important in the triggering of the landslide.

The Hunga Tonga-Hunga Ha’apai eruption of January 15 2022 was the culminating event of a sequence of seismic and volcanic events starting back in December 2021. The January 15 eruption manifested itself above the sea level with a number of phenomena, including the generation of a convective column ascending well into the stratosphere, pyroclastic flows travelling over the sea surface, an atmospheric pressure wave recorded by several instruments around the globe, and a tsunami, that represents the main focus of this study.The tsunami that followed the eruption was observed both in the near-field and in the far-field, propagating across the entire Pacific Ocean and causing damage and loss of lives as far as Peru. In the near-field (Tonga archipelago) it is trickier to distinguish the damage induced by the impact of the eruption and the tsunami waves.It is still not clear what the main generating mechanism for the ensuing tsunami was. In this contribution, several different hypotheses are investigated, adopting simplified models ranging from the submerged volcanic edifice collapse to the phreatomagmatic explosion and to the atmospheric pressure wave that was recorded across the entire globe. The propagation of the tsunami is simulated numerically with both non-dispersive and dispersive codes. Different spatial scales and resolutions are adopted to check the relative weight of the different generating mechanisms in the near- and in the far-field. Tentative conclusions are drawn by comparing the simulated results with the available experimental data in terms of tide-gauge records and near-field coastal impact.

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.

We propose a methodology to assess tsunami risk in terms of human damage (HD: the quantification of people affected/killed by the tsunami) and economic loss (EL: the loss of the economic value of constructions damaged/destroyed by the tsunami). The methodology makes a combined use of detailed information on buildings, demography and reasonable tsunami inundation heights (IH). First, after defining the tsunami inundation area, we estimate the level of damage to each building within this area, which depends on the building vulnerability and on the flow depth (FD) affecting the building. To estimate the HD, by making use of census data, we infer the number of people present in each residential building of the inundated area. Then, based on FD and building damage, we evaluate the level of people exposure. Finally, we provide an estimate of fatalities. The EL is computed for two types of constructions (residential and trade/industrial) by using data on inundation and data from the real estate market. The methodology is applied to the town of Augusta (eastern Sicily coast, Italy), which, according to historical accounts, was affected by several tsunamis in the course of its history. The results are discussed in terms of the level of damage to buildings, the number of fatalities and the loss of economic value of the building stock for different tsunami sizes. This latter is prescribed through a simple bathtub approach: that is, by assuming uniform IHs with the maximum IH chosen to be consistent with historical data. Partial collapse occurs only above 6 m for residential buildings and above 8 m for trade/industrial buildings. Approximately 47% of the people living in Augusta are potentially affected by the tsunami inundation. For the highest selected IH (10 m), 70% of the people in the inundated area are effectively exposed and the fatalities are estimated at about 47%. The number of people involved increases linearly with the IH, while the number of fatalities increases following a quasi-quadratic law. Finally, the EL is also found to vary linearly with the IH, and the estimated loss in the case of the worst IH (10 m) is around 11% of the gross domestic product (GDP) of the entire province of Siracusa, to which Augusta belongs.

Karpathos is one of the biggest Greek islands, located between Crete and Rhodes in Aegean Sea. As the most of the islands in the area Karpathos is prone to earthquakes and tsunamis. The event of 9 February 1948 (M 7.1) near the eastern coast of the island caused local tsunami with damages in the area of Pigadia bay, nevertheless tsunamis also from regional sources are expected. The tsunami hazard for the Karpathos Island, focusing on the city of Karpathos and the Airport area, is modelled merging the data from simulation of tsunamis generated by three seismic sources: Eastern Hellenic Arc (EHA referring the 1303 A.D. event, Mw = 8.0); near Rhodes (hypothetical scenario earthquake, Mw = 7.3); and near the coast of Karpathos, based on the 1948, Mw = 7.3 earthquake. Numerical calculations are made using the code UBO-TSUFD on a set of nested grids. Tsunami observables, such as maximal water column height, maximum velocity flux, inundation, are computed for each individual scenario and merged to individuate the areas most exposed to tsunami. The seismic source EHA dominates in the tsunami hazard maps: moreover, the impact over the southern part of Karpathos has biggest risk since the airport and the main city of the island are located in this part.

The 1963 Vajont landslide is a key case in landslide literature, because it was catastrophic and because a lot of accurate data were collected before and after its occurrence. In this paper, the main focus is on the possible heterogeneity of the sliding surface involved by the landslide motion, which is reflected by a heterogeneous distribution of the dynamic basal friction coefficient l. Assuming a given zonation of the sliding surface, our strategy was to apply a 2D Lagrangian model to compute the landslide motion and to find the values of l for each zone, leading to the best agreement between the computed and the observed final deposit. Following some hints from the literature, we have explored heterogeneous configurations composed of up to four different zones, including also the homogeneous case, by means of a 2D numerical model (UBO-BLOCK2) that handles the landslide as a mesh of blocks and runs quickly enough to allow the computation of tens of thousands of simulations in a reasonable computing time. It is found that the four-zone zonation produces the best fit (or the least misfit), which is a strong hint that the gliding surface involved different geotechnical units.

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.

Mt. Athos, Northern Greece, is a monastic community with life since ~ 1000 AD, a UNESCO worldwide cultural heritage site that was repeatedly hit by earthquakes. On 8 November 1905, a large earthquake, with estimated magnitude ranging from 6.8 to 8.3, caused destruction in Mt. Athos, but the event remains little known since only few documentary sources have been utilized so far. We collected a set of sources including contemporary press reports, letters, manuscripts and books. We reconstructed the earthquake impact field and organized a database containing (1) assignment of macroseismic intensity in 44 observation points at epicentral distances up to ~ 660km, and (2) identification of sites where important co-seismic ground failures were reported, e.g., landslides and rock falls. From magnitude-intensity relationships, a macroseismic magnitude of ~ 7 equivalent to Ms was estimated, which is close to recent instrumental estimates of ~ Mw 7.2. The examined sources revealed for the first time that a local but powerful tsunami with an ~ 3-m run-up was generated by earthquake-triggered landslides in southern Mt. Athos. Eleven persons were reportedly killed. Both the landslide and the tsunami were numerically simulated by a scenario of massive landslide entering the sea. The synthetic marigrams obtained from the simulation are consistent with the historical tsunami descriptions. Another little-known tsunami was reported in Mt. Athos in association to the large 1585 earthquake. We concluded that a comprehensive hazard assessment in Mt. Athos should take into account not only strong earthquakes but also associated phenomena like landslides and tsunamis.

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.

This paper is the second of two companion papers addressing the dynamics of two coupled masses sliding on analytical surfaces and interacting with one another. The motion occurs under the effect of gravity, the reaction force of the surface and basal friction. The interaction force maintains the masses at a fixed distance and lies on the line connecting them. The equations of motion form a system of ordinary differential equations that are solved through a fourth-order Runge–Kutta numerical scheme. In the first paper we considered an approximate method holding when the line joining the masses is almost tangent to the surface at the instant mass positions. In this second paper we provide a general solution. Firstly, we present special cases in which the system has exact solutions. Second, we consider a series of numerical examples where the interest is focused on the trajectories of the masses and on the intensity and changes of the interaction force. Keywords: Two-point system, Rigid-body motion, Sliding downslopes

In this study, we introduce a system of differential equations describing the motion of a single point mass or of two interacting point masses on a surface, that is solved by a fourth-order explicit Runge–Kutta (RK4) scheme. The forces acting on the masses are gravity, the reaction force of the surface, friction, and, in case of two masses, their mutual interaction force. This latter is introduced by imposing that the geometrical distance between the coupled masses is constant. The solution is computed under the assumption that the point masses strictly slide on the surface, without leaping or rolling. To avoid complications stemming from numerical errors related to real topographies that are only known over discrete grids, we restrict our attention to simulations on analytical continuous surfaces. This study sets the basis for a generalization to more complex systems of masses, such as chains or matrices of blocks that are often used to model complex processes such as landslides and rockfalls. The results shown in this paper provide a background for a companion paper in which the system of equations is generalized, and different geometries are presented. Keywords: Point-mass sliding, Two point-mass systems, Analytical surfaces, Numerical methods, Runge–Kutta method

It is well known that for earthquake-generated tsunamis impacting near-field coastlines the focal mechanism, the position of the fault with respect to the coastline and the on fault slip distribution are key factors in determining the efficiency of the generation process and the distribution of the maximum run-up and inundation along the nearby coasts. The time needed to obtain the aforementioned information from the analysis of seismic records is usually too long compared to the time required to issue a timely tsunami warning/alert to the nearest coastlines. In the context of tsunami early warning systems, a big challenge is hence to be able to define 1) the relative position of the hypocenter and of the fault and 2) the earthquake focal mechanism, based only on the preliminary earthquake localization and magnitude estimation, which are made available by seismic networks soon after the earthquake occurs.In this study, the intrinsic unpredictability of the position of the hypocenter on the fault plane is studied through a probabilistic approach based on the analysis of two finite fault model datasets (SRCMOD and USGS) and by limiting the analysis to moderate-to-large shallow earthquakes (Mw 6 and depth 50 km). After a proper homogenization procedure needed to define a common geometry for all samples in the two datasets, the hypocentral positions are fitted with different probability density functions (PDFs) separately in the along-dip and along-strike directions.Regarding the focal mechanism determination, different approaches have been tested: the most successful is restricted to subduction-type earthquakes. It defines average values and uncertainties for strike, dip and rake angles based on a combination of a proper zonation of the main tsunamigenic subduction areas worldwide and of subduction zone geometries available from publicdatabases.The general workflow that we propose can be schematically outlined as follows. Once an earthquake occurs and the magnitude and hypocentral solutions are made available by seismic networks, it is possible to assign the focal mechanism by selecting the characteristic values for strike, dip and rake of the zone where the hypocenter falls into. Fault length and width, as well as the slip distribution on the fault plane, are computed through regression laws against magnitude proposed by previous studies. The resulting rectangular fault plane can be discretized into a matrix of subfaults: the position of the center of each subfault can be considered as a “realization” of the hypocenter position, which can then be assigned a probability. In this way, we can define a number of earthquake fault scenarios, each of which is assigned a probability, and we can run tsunami numerical simulations for each scenario to quantify the classical observables, such as water elevation time series in selected offshore/coastal tide-gauges, flow depth, run-up, inundation distance. The final results can be provided as probabilistic distributions of the different observables.The general approach, which is still in a proof-of-concept stage, is applied to the 16 September 2015 Illapel (Chile) tsunamigenic earthquake (Mw = 8.2). The comparison with the available tsunami observations is discussed with special attention devoted to the early-warning perspective.

Notwithstanding its complexity in terms of numerical implementation and limitations in coping with problems involving extreme deformation, the finite element method (FEM) offers the advantage of solving complicated mathematical problems with diverse boundary conditions. Recently, a version of the particle finite element method (PFEM) was proposed for analyzing large-deformation problems. In this version of the PFEM, the finite element formulation, which was recast as a standard optimization problem and resolved efficiently using advanced optimization engines, was adopted for incremental analysis whilst the idea of particle approaches was employed to tackle mesh issues resulting from the large deformations. In this paper, the numerical implementation of this version of PFEM is detailed, revealing some key numerical aspects that are distinct from the conventional FEM, such as the solution strategy, imposition of displacement boundary conditions, and treatment of contacts. Additionally, the correctness and robustness of this version of PFEM in conducting failure and post-failure analyses of landslides are demonstrated via a stability analysis of a typical slope and a case study on the 2008 Tangjiashan landslide, China. Comparative studies between the results of the PFEM simulations and available data are performed qualitatively as well as quantitatively.

The Marsili Seamount (Tyrrhenian Sea, Italy) is the largest submarine volcano in the Mediterranean Sea, located in the middle of the Marsili Basin, facing the Calabrian and Sicilian coasts on its eastern side, and the coasts of Sardinia on the opposite side. It has erupted in historical times, and its summit crest is affected by widespread hydrothermal activity. This study looks at mass failures taking place at different depths on the flanks of the volcano and estimates their associated tsunamigenic potential. Mass failure, tsunami generation, and propagation have been simulated by means of numerical models developed by the Tsunami Research Team of the University of Bologna. In all, we consider five cases. Of these, three scenarios, one regarding a very small detachment and two medium-sized ones (between 2 and 3 km3 failure volume), have been suggested as possible failure occurrences in the published literature on a morphological basis and involve the north-eastern and north-western sectors of the volcano. The two additional cases, one medium-sized and one extreme, intended as a possible worst-case scenario (volume 17.6 km3), affecting the eastern flank. Results indicate that small-volume failures are not able to produce significant tsunamis; medium-size failures can produce tsunamis which dangerously affect the coasts if their detachment occurs in shallow water, i.e., involves the volcano crest; and extreme volume failures have the potential to create disastrous tsunamis. In all the simulations, tsunami waves appear to reach the Aeolian Islands in around 10 min and the coasts of Calabria and Sicily in 20 min. This study highlights that there is a potential for dangerous tsunamis generation from collapses of the Marsili volcano and as a consequence a need to intensify research on its status and stability conditions. More broadly, this investigation should also be extended to the other volcanic seamounts of the Tyrrhenian Sea, since their eruptive style, evolution, and tsunamigenic potential are still poorly known.

Coastal boulders transported inland by marine hazards, such as tsunamis and storms, are commonly found worldwide. Studies on the transport process of coastal boulders contribute to the understanding of a wide range of phenomena such as high-energy flow events, fluid-structure interaction, and coastal sediments. Consequently, it is crucial to understand how boulders move, but even more important to determine the instability condition for boulder transport. The hydrodynamic formulas including drag and lift coefficients are widely used to predict the incipient motion of boulders while few studies are conducted to evaluate the capability of these formulas. Recently, a series of laboratory experiments carried out at the Hydraulic Engineering Laboratory (Italian acronym LIDR) of the University of Bologna, Italy, revealed that boulders can start moving when the flow height and flow velocity are lower than the theoretical threshold computed by hydraulic formulas. In this paper, we use a numerical shallow water model to reproduce these freely available laboratory data with the aim of testing the capability of the model in capturing the main evolution of the process, and of casting new light on the instability condition of coastal boulders.

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.

The Palinuro volcanic chain is located nearly 80 km offshore the Campania coasts (Italy), in the southern sector of the Tyrrhenian Sea. As many as 15 distinct volcanic edifices have been recently detected that covers a 90 km long and 20 km wide belt. The associated volcanism is still poorly understood but the presence of shallow seismicity and active hydrothermal activity suggest that this large volcanic complex is still active. Specific sectors of the chain show the presence of ongoing slope instability and thus the chance of mass movements cannot be ruled out in case of seismic or volcanic activity. In this work, a stability analysis for typical seismic loads in such a volcanic area has been performed through a revised limit equilibrium approach. In the revealed weaker sections, three mass failures of different scales have been reconstructed and their motion has been calculated by means of numerical models. The tsunami produced by each slide has been simulated, and considerable waves have been found in two of the three hypothesized scenarios. For the biggest slide of 2.4 km3, waves as high as 10 m could reach portions of the Calabria coasts with consequent hazardous impact.This study belongs to a series of works focused on the volcanoes of the Tyrrhenian Sea that are very many and still poorly investigated. Considering scenarios involving mass movements of different sizes with distinct characteristics and based on geomorphological features seems to be a viable strategy to evaluate the tsunami hazard in the region.

Siracusa is an important historical city of Greek origin, located on the southern part of the eastern coast of Sicily. The old town developed on the island of Ortigia, and expanded on the near mainland, but later it declined and during the Middle Ages it occupied only the island. The development of the built areas on the mainland restarted at the end of the nineteenth century, with the construction of a number of new quarters. Nowadays the island of Ortigia is connected to the rest of the town by two drive-over bridges. The history of Siracusa as well as of the eastern coast of Sicily is marked by destructive earthquake events that caused significant damage and many fatalities, and also by lethal tsunamis (occurred in the years 1169, 1693 and 1908). Indeed, this region is one of the coastal areas most prone to tsunami attacks in the Mediterranean Sea, being affected by local-source tsunamis and also by those generated by earthquakes in the Western Hellenic Arc.For these reasons, in the last decade the need has developed to prepare adequate evacuation measures to respond to tsunami hazardous events. This work, using the method proposed by Pagnoni et al. (2020) and applied to the near town of Augusta, studies the tsunami risk for different inundation levels. The results are provided in terms of the Human Damage (HD), which is the number of people involved and the number of fatalities, and of the Economic Loss (EL), which returns the loss of economic value of buildings affected by tsunamis. Maps of HD and EL per each inundation scenario allow one to understand which areas of Siracusa are most involved and also to identify evacuation paths to potential safe collection areas and/or buildings for efficient emergency plans.

The study presented here takes the move from two well-known premises in tsunami science: the slip distribution on earthquake faults is heterogeneous and, in the case of tsunamigenic earthquakes, slip heterogeneity influences significantly the distribution of tsunami run-ups, especially for near-field areas. In the perspective of tsunami early warning, a crucial issue is to obtain a reasonable slip distribution within a time significantly shorter than the time taken by the waves to impact the nearest coastlines.When an earthquake occurs, the only information that becomes available after a few minutes concerns the location of the earthquake and its magnitude. The first finite-fault models (FFM), based on seismic/geodetic data inversion, become available several hours or even days after the earthquake origin time. In the case of tsunamigenic earthquakes, tsunami waveforms useful for inversion become available after the tsunami passage at the recording stations. From the warning perspective, the time to get FFM representations is therefore too long for the near-source coastal areas. We propose and describe a strategy whose goal is to derive in quasi-real-time a reasonable representation of the heterogeneous slip distribution on the fault responsible for a given tsunamigenic earthquake and to forecast the run-up distribution along the nearest coastlines. The strategy is illustrated in its application to the 16 September 2015 Illapel (Chile) tsunamigenic earthquake.Realistically, the hypocentre location and the magnitude of the event can be available within two-three minutes. Knowing the hypocentre location permits us to place the fault plane in a definite geographical reference, while the knowledge of magnitude allows to derive the fault dimension and the slip model. A key point here is that we can derive slip models only knowing the magnitude and the location of the hypocenter. Among these models, we adopt simple 2D Gaussian Distributions (GDs), representing the main asperity, whose parameters can be deduced from properly defined regression laws. The 2D-GD simple representation takes a very short time to be derived. To complete the characterization of the tsunamigenic source, focal parameters can be safely derived from seismological databases, while the position of the fault represents a trickier point, as the fault plane is not necessarily centered at the earthquake hypocentre. To take this uncertainty into account, as a first approach three faults for each slip model are considered: 1) a plane centered on the hypocentre, 2) a fault shifted northwards, 3) a fault shifted southwards. We run tsunami simulations for each adopted slip distribution and for each fault position, and compare the results against the available observed tide-gauge and run-up data in the near-field. We compare the performance of our 2D-GD models with respect to the finite-fault models retrieved from inversion procedures, published months after the 2015 event. We demonstrate that the 2D-GD method performs very satisfactorily in comparison to more refined, non-real-time published FFMs and hence permits to produce reliable real-time tsunami simulations very quickly and can be used as an experimental procedure in the frame of operational tsunami warning systems.

In the framework of the OPERANDUM (OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks) project, modelling the effect of the Nature Based Solutions (NBS) on selected open-air laboratories plays a determinant role. In this work, we focus the attention on the Vögelsberg (Tyrol, Austria) landslide case study, located in the municipality of Wattens. The 0.25 km2 active part of the slope shows annual movement rates in the order of 3.5-6 cm/a. Recent studies provided evidence that the motion is mainly driven by variations of the groundwater level. The latter are related to prolonged moist periods during which excessive rainfall or snow melt water can infiltrate and act on the geo-hydrological system. With the aim of enhancing the slope stability employing NBS, a detailed analysis of the hydrogeology and the slope characteristics have been carried out, obtaining the required technical parameters describing the involved soil material. Furthermore, a slope stability analysis by means of different numerical models has been performed. Results prove that variations of the groundwater level in the range of 1-2 m can strongly affect the stability of the slope. Thus, specific NBS should aim at reducing the amount of infiltrating water. Examples of such NBS include the adaptation of forest management and land use planning, the introduction and re-activation of drainage channels and the sealing of leaky streams and channels. Beside the effects of the variation of the groundwater level, results have proved that the slope could fail under the action of a moderate seismic load. In this scenario, it is likely that the effects of the NBS would be insufficient to maintain the slope intact.

Modelling of landslides in sensitive clays has long been recognised as a challenge. The strength reduction of sensitive clays when undergoing plastic deformation makes the failure proceed in a progressive manner such that a small slope failure may lead to a series of retrogressive failures and thus to an unexpected catastrophic landslide. The clay in the entire process may mimic both solid-like (when it is intact) and fluid-like (when fully remoulded, especially for quick clays) behaviours. Thereby, a successful numerical prediction of landslides in sensitive clays requires not only a robust numerical approach capable of handling extreme material deformation but also a sophisticated constitutive model to describe the complex clay behaviour. In this paper, the particle finite element method (PFEM) associated with an elastoviscoplastic model with strain softening is adopted for the reconstruction of the 2010 Saint-Jude landslide, Quebec, Canada, and detailed comparisons between the simulation results and available data are carried out. It is shown that the present computational framework is capable of quantitatively reproducing the multiple rotational retrogressive failure process, the final run-out distance and the retrogression distance of the Saint-Jude landslide. Furthermore, the failure mechanism and the kinematics of the Saint-Jude landslide and the influence of the clay viscosity are investigated numerically, and in addition, their implications to real landslides in sensitive clays are discussed.

In this study, we present a new 2D numerical model, UBO-Inter, able to simulate the motion of a body sliding down a generic surface. Such a body is represented as a mechanical system of a finite number of point masses, where the points can be viewed as the projections on the sliding surface of the centers of mass of the elements which the system is discretized into. The masses are strictly adherent to the surface and interact with the neighbor masses through internal forces. The entire system can be seen as a 2D irregular grid where the masses occupy the nodes of the grid, and each grid side connects a pair of interacting masses. The external forces acting on the masses are gravity, which is the driving force, the reaction force of the sliding surface, the basal friction and the drag exerted by the environmental fluid (typically water, for a slide moving partially or totally underwater). The system is governed by a set of differential equations that are solved through a fourth-order Runge–Kutta scheme. After providing the formulation of the problem and a simple example admitting an exact solution that serves to illustrate the internal forces, we validate the model on the 1783 Scilla (Calabria region, Italy) landslide, that is a well-known catastrophic event that caused a lethal tsunami killing more than 1500 people. This case has been already widely studied and thus can be used as a benchmark for landslide models. The outputs of the model UBO-Inter in terms of time-histories of point-mass velocities, run-out and final deposit, are found to be in agreement with observations and with results published in literature and obtained through different numerical techniques.

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.

Ischia is a volcanic island located at the margin of the Gulf of Naples in the southeastern Tyrrhenian Sea, Italy. In this article, we investigate the stability of the deep‐seated block known as Mt. Nuovo in the northwestern flank of the Mt. Epomeo volcano under a combined gravitational and seismic load. Mt. Nuovo is bounded by a number of active seismic faults and is placed close to the epicentral area of the 1883 Casamicciola earthquake (I MCS =X, M w 5.8), that is, the largest shock occurring in the island in historical times. We explore the hypothesis that a Casamicciola‐like earthquake might occur with an epicenter in the Mt. Nuovo block area. Using relationships between maximum seismic intensity and peak ground acceleration found in the literature as well as a new relationship derived specifically for this study, we apply the minimum lithostatic deviation method, which is a variant of the limit‐equilibrium method, to assess the stability of the block. The main finding is that Mt. Nuovo would be mobilized if such an earthquake took place on a fault very close to the block, which would give rise to a catastrophic mass failure and to a disastrous tsunami. This calls for the need of continuous monitoring of the volcano seismicity and deformation pattern.

Eastern Sicily is affected by earthquakes and tsunamis of local and remote origin, which is known through numerous historical chronicles. Recent studies have put emphasis on the role of submarine landslides as the direct cause of the main local tsunamis, envisaging that earthquakes (in 1693 and 1908) did produce a tsunami, but also that they triggered mass failures that were able to generate an even larger tsunami. The debate is still open, and though no general consensus has been found among scientists so far, this research had the merit to attract attention on possible generation of tsunamis by landslides off Sicily. In this paper we investigate the tsunami potential of mass failures along one sector of the Hyblean-Malta Escarpment (HME). facing Augusta. The HME is the main offshore geological structure of the region running almost parallel to the coast, off eastern Sicily. Here, bottom morphology and slope steepness favour soil failures. In our work we study slope stability under seismic load along a number of HME transects by using the Minimun Lithostatic Deviation (MLD) method, which is based on the limit-equilibrium theory. The main goal is to identify sectors of the HME that could be unstable under the effect of realistic earthquakes. We estimate the possible landslide volume and use it as input for numerical codes to simulate the landslide motion and the consequent tsunami. This is an important step for the assessment of the tsunami hazard in eastern Sicily and for local tsunami mitigation policies. It is also important in view of tsunami warning system since it can help to identify the minimum earthquake magnitude capable of triggering destructive tsunamis induced by landslides, and therefore to set up appropriate knowledge-based criteria to launch alert to the population.

Numerical modelling is a powerful tool to study the mechanism of landslides and constructs the foundation of many physically-based assessment methods applied to natural hazards. Usually, numerical analyses of landslides are carried out on the failure mechanism and on the propagation process separately. With the advantage of dealing with large deformation problems, the particle finite element method (PFEM), that is the particle extension of the traditional FEM, has the capability of simulating the entire evolution of the landslide from the generation to the deposition phase. To figure out the difference between a unified PFEM simulation and the usually adopted approaches that separate failure mechanism (static analysis) and run-out analysis (dynamic analysis), we implement a PFEM code that is applied first to a simple homogeneous slope model. Numerical results reveal that under the so-called critical condition the landslide comes to a stop with a slight modification of the original profile, while its profile is drastically changed if strength reduction is further applied. To test the capability of our model, we choose the 2013 Cà Mengoni landslide, northern Apennines, Italy, as a case study, since it behaved as if it were formed by homogeneous material. In virtue of the back-analysis of the run-out distance that we perform by using different material strength parameters, we show that the PFEM model is able to capture the variation of the observed landslide profile, and contributes to the understanding of the dynamics of the whole sliding process.

The 1783 Scilla tsunami, induced by a coastal landslide occurring during an intense seismic sequence in Calabria (South Italy), was one of the most lethal ever observed in Italy. It caused more than 1500 fatalities, most of which on the 10 beach close to the town where people gathered to escape earthquake shaking. In this paper, complementing a previous work (Zaniboni et al., 2016) focusing on the very local tsunami effects in the town of Scilla, we study the tsunami impact on the Calabria and Sicily coasts out of Scilla. To this purpose we take into account the same landslide geometry considered in the previous study and perform three tsunami simulations, one embracing a larger region with a 50-m computational grid, and two covering the specific area of Capo Peloro, in Sicily, facing Scilla on the western side of the Messina Straits, with even 15 higher resolution (10 m mesh). Numerical results show a very good agreement with the historical observations in Capo Peloro. Moreover, the resulting global tsunami inundation pattern provides a useful hint for tsunami hazard assessment in the Messina Straits area, which is known to be one of the most exposed to tsunami threat in Italy and in the Mediterranean Sea.

In this paper, a novel mathematical programming formulation is derived based on the u-p form for the dynamic analysis of saturated porous media. A mixed finite element is used for the interpolation of field variables and after discretization the formulation is remolded into a standard second-order cone programming problem that can be resolved using modern optimization engines. The proposed optimization-based computational scheme is verified against typical benchmarks such as the dynamic consolidation problem and the wave propagation in saturated soils. To tackle issues such as mesh distortions and severe free-surface evolutions resulting from large deformations, the scheme is further implemented into the PFEM framework. The capability of the proposed method for analyzing porous media with large deformations is illustrated by modelling the collapse of a saturated granular column in air and the post-failure process of an embankment due to seepage with results compared to the ones from lab tests and numerical simulations using other approaches such as the material point method and the smoothed particle hydrodynamics method.

Many natural disasters can be related to wave processes, either due to the destructive wave impact, as in the case of tsunamis, storm waves and surges, and oceanic rogue waves, or due to indirect effects, such as wave sediment transport, landslides induced by earthquakes, etc. These phenomena affect millions of people annually and may result in billions of dollars losses. From the scientific point of view, catastrophic wave phenomena are often related to essentially nonlinear dynamics and nontrivial nonlinear effects. Thus, vital practical needs lead to challenges in nonlinear physics and mathematics. The consequent fundamental theoretical problems are important in their own right, and the dynamical understanding develops and may even change in the course of obtaining solutions. The application stage is when the developed theoretical approaches are directed back to the geophysical issue with success in improved understanding, or the contrary, with insufficient effectiveness which motivates further fundamental research.

Siracusa is one of the most important cities of the eastern coast of Sicily, which according to historical records and to the present knowledge of the tectonic setting, is exposed to tsunamis generated by landslides on the Malta escarpment and by local and remote (e.g., Eastern Hellenic Arc) earthquakes. For this reason, the area of Siracusa has been selected as one of the test sites to conduct specific studies within the European FP7 project ASTARTE. In this frame, this work focuses on the assessment of tsunami vulnerability of (and damage to) the building stock of the town. The analysis is carried out following two different models, namely the SCHEMA and the Papathoma Tsunami Vulnerability Assessment (PTVA-3) methods. Topographic and building stock data in the potentially flooded areas are taken from detailed digital databases produced by the region of Sicily, integrated with satellite and photographic imagery from Google Earth and further validated by field surveys. We have explored three inundation scenarios corresponding to a constant-level tsunami flooding with assumed sea level rise of 1, 3 and 5 m, and evaluated the damage to the town buildings using both methods that make use of a 5-degree scale. The main result is that the level of damage of both models is not consistent, and that consistency may be improved if one changes from a 5- to a 3-degree damage scale.

Alexandria is the second biggest city in Egypt with regards to population, is a key economic area in northern Africa and has very important tourist activity. Historical records indicate that it was severely affected by a number of tsunami events. In this work we assess the tsunami hazard by running numerical simulations of tsunami impact in Alexandria through the worst-case credible tsunami scenario analysis (WCTSA). We identify three main seismic sources: the western Hellenic Arc (WHA – reference event AD 365, Mw = 8.5), the eastern Hellenic Arc (EHA – reference event 1303, Mw = 8.0) and the Cyprus Arc (CA – hypothetical scenario earthquake with Mw = 8.0), inferred from the tectonic setting and from historical tsunami catalogues. All numerical simulations are carried out in two sea level conditions (mean sea level and maximum high-tide sea level) by means of the code UBO-TSUFD, developed and maintained by the Tsunami Research Team of the University of Bologna. Relevant tsunami metrics are computed for each scenario and then used to build aggregated fields such as the maximum flood depth and the maximum inundation area. We find that the case that produces the most relevant flooding in Alexandria is the EHA scenario, with wave heights up to 4 m. The aggregate fields are used for a building vulnerability assessment according to a methodology developed in the framework of the EU-FP6 project SCHEMA and further refined in this study, based on the adoption of a suitable building damage matrix and on water inundation depth. It is found that in the districts of El Dekhila and Al Amriyah, to the south-west of the port of Dekhila, over 12 000 (13 400 in the case of maximum high tide) buildings could be affected and hundreds of them could sustain damaging consequences, ranging from critical damage to total collapse. It is also found that in the same districts tsunami inundation covers an area of about 15 km2, resulting in more than 150 000 (165 000 in the case of maximum high tide) residents being exposed.

The Palinuro volcanic chain (PVC) is located about 80 km offshore the Campania region (Italy) in the southern sector of the Tyrrhenian Sea. The chain consists of 15 volcanic edifices aligned in an E-W direction with two distinct major seamounts (Palinuro and Glabro). They cover a 90 km long and 20 km wide area, with a present-day volume of 2700 km3. Palinuro volcanism emplaced between 0.8 and 0.3 Ma, although shallow seismicity and hydrothermalism indicate an ongoing volcanic activity. A geomorphological analysis of the volcanic chain and data from a multichannel seismic profile reveal large volumes of buried chaotic material suggesting gravity mass sliding from the volcano flanks and slide scars. A stability analysis of the Palinuro flanks has been carried out to determine the sectors potentially prone to sliding in case of shallow volcanic earthquakes. Landslides are simulated by adopting a scenario-based approach. Tsunamis induced by these mass movements and their propagation across the Tyrrhenian Sea are modeled. Results suggest that shallow earthquakes (M ~4.6–4.8) are able to destabilize the flanks of the volcanic chain generating slope failures. Sliding volumes in the order of 1.5 km3 and 2.4 km3 may induce waves as high as 1.5 and 6 m, respectively, along the peri-Tyrrhenian coast. Our results underline the need for further investigations on the stability of the submarine volcanoes of the Tyrrhenian basin. These volcanoes are still poorly known although their instability could trigger large tsunamis along the southern Italy coastal sectors. Our recommendation is that multiparamertic monitoring networks on PVC and periodic oceanic cruises should be put into action, and further that a systematic evaluation of the tsunami hazard related to possible sliding phenomena on the flanks of the Tyrrhenian seamounts should be performed.

South-eastern Sicily has been affected by large historical earthquakes, including the 11 January 1693 earthquake, considered the largest magnitude earthquake in the history of Italy (Mw = 7.4). This earthquake was accompanied by a large tsunami (tsunami magnitude 2.3 in the Murty-Loomis scale adopted in the Italian tsunami catalogue by Tinti et al., 2004), suggesting a source in the near offshore. The fault system of the eastern Sicily slope is characterised by NNW–SSE-trending east-dipping extensional faults active in the Quaternary. The geometry of a fault that appears currently active has been derived from the interpretation of seismic data, and has been used for modelling the tsunamigenic source. Synthetic tide-gauge records from modelling this fault source indicate that the first tsunami wave polarity is negative (sea retreat) in almost all the coastal nodes of eastern Sicily, in agreement with historical observations. The outcomes of the numerical simulations also indicate that the coastal stretch running from Catania to Siracusa suffered the strongest tsunami impact, and that the highest tsunami waves occurred in Augusta, aslo in agreement with the historical accounts. A large-size submarine slide (almost 5 km3) has also been identified along the slope, affecting the footwall of the active fault. Modelling indicates that this slide gives non-negligible tsunami signals along the coast; though not enough to match the historical observations for the 1693 tsunami event. The earthquake alone or a combination of earthquake faulting and slide can possibly account for the large run up waves reported for the 11 January 1693 event.

We present a first detailed tsunami risk assessment for the city of Messina where one of the most destructive tsunami inundations of the last centuries occurred in 1908. In the tsunami hazard evaluation, probabilities are calculated through a new general modular Bayesian tool for Probability Tsunami Hazard Assessment. The estimation of losses of persons and buildings takes into account data collected directly or supplied by: (i) the Italian National Institute of Statistics that provides information on the population, on buildings and on many relevant social aspects; (ii) the Italian National Territory Agency that provides updated economic values of the buildings on the basis of their typology (residential, commercial, industrial) and location (streets); and (iii) the Train and Port Authorities. For human beings, a factor of time exposition is introduced and calculated in terms of hours per day in different places (private and public) and in terms of seasons, considering that some factors like the number of tourists can vary by one order of magnitude from January to August. Since the tsunami risk is a function of the run-up levels along the coast, a variable tsunami risk zone is defined as the area along the Messina coast where tsunami inundations may occur. © 2012 Author(s). CC Attribution 3.0 License.

Rapporto intermedio. ACCORDO OPERATIVO 2016 tra Consiglio Nazionale delle Ricerche - Istituto di Scienze Marine (ISMAR CNR) e Ministero dello Sviluppo Economico, Direzione Generale per la Sicurezza anche ambientale delle attivit? minerarie ed energetiche - Ufficio Nazionale Minerario per gli Idrocarburi e le Georisorse (DGS-UNMIG).

Italy is one of the most seismically active regions in the central Mediterranean and one of the countries with the longest record of historical earthquakes in the world. Over the last decades the scientific community has recognised the value of historical data when used to constrain modelling tools in hazard analyses. This is the case of the destructive 1905 Calabria (South Italy) earthquake, followed by a tsunami and by many secondary effects on the environment observed both inland and offshore. Recently acquired geophysical data allowed to identify an active normal fault, named Sant'Eufemia Fault, located nearshore in the Sant'Eufemia Gulf (SE Tyrrhenian sea), considered the most probable seismogenic source of the 1905 earthquake and capable to trigger future events. In this paper we perform a scenario-based deterministic analysis for an earthquake resulting from the rupture of the Sant'Eufemia fault (SEF) and a preliminary potential risk analysis. After defining source parameters compatible with the 1905 earthquake (ca. 40 km fault length and ca. 2.3 m slip, Mw 6.9), KF-analysis and tsunami simulations are carried out and modelling results are compared against historical available data. The obtained results allow one to border areas in central Calabria that are most exposed to geohazard deriving from the analyzed fault. Some of these areas happen to be zones with intense economic/touristic and urban development, which calls for the need to integrate the ongoing development plans with adequate programs of risk mitigation and prevention.

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.

Nowadays numerical models are a powerful tool in tsunami research since they can be used (i) to reconstruct modern and historical events, (ii) to cast new light on tsunami sources by inverting tsunami data and observations, (iii) to build scenarios in the frame of tsunami mitigation plans, and (iv) to produce forecasts of tsunami impact and inundation in systems of early warning. In parallel with the general recognition of the importance of numerical tsunami simulations, the demand has grown for reliable tsunami codes, validated through tests agreed upon by the tsunami community. This paper presents the tsunami code UBO-TSUFD that has been developed at the University of Bologna, Italy, and that solves the non-linear shallow water (NSW) equations in a Cartesian frame, with inclusion of bottom friction and exclusion of the Coriolis force, by means of a leapfrog (LF) finite-difference scheme on a staggered grid and that accounts for moving boundaries to compute sea inundation and withdrawal at the coast. Results of UBO-TSUFD applied to four classical benchmark problems are shown: two benchmarks are based on analytical solutions, one on a plane wave propagating on a flat channel with a constant slope beach; and one on a laboratory experiment. The code is proven to perform very satisfactorily since it reproduces quite well the benchmark theoretical and experimental data. Further, the code is applied to a realistic tsunami case: a scenario of a tsunami threatening the coasts of eastern Sicily, Italy, is defined and discussed based on the historical tsunami of 11 January 1693, i.e. one of the most severe events in the Italian history.