Mathematical Optimization Problems for Particle Finite Element Analysis Applied to 2D Landslide Modeling

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Landslide deposits

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

Earthquake-triggered landslides along the Hyblean-Malta Escarpment (off Augusta, eastern Sicily, Italy) – assessment of the related tsunamigenic potential

Abstract. 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

The AD 365 Crete Earthquake/Tsunami Submarine Impact on the Mediterranean Region

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 25 m 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 2000 km 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

Reconstruction of the 1783 Scilla landslide, Italy: numerical investigations on the flow-like behaviour of landslides

This paper presents a mass flow model that includes gravity force, material stresses, drag force and topography effects solving a set of hyperbolic partial differential equations by using a so-called depth-averaged technique. The model is non-linear and general enough to tackle various problems of interest for geophysics and environmental engineering, such as the dynamic evolution of flow-like avalanches, the dam break problem (involving only water flow) and the generation of tsunami waves by landslides. The model is based on a Eulerian fluid solver, using a second-order central scheme with a minmod-like limiter; is tested against a number of typical benchmark cases, including analytical solutions and experimental laboratory data; and also compared with other numerical codes. Through this model, we study a historical tsunamigenic event occurred in 1783 in Scilla, Italy, that resulted to be catastrophic with a toll exceeding 1500 fatalities. The landslide is reconstructed by a mixture debris flow, and results are compared with the observational data and other numerical simulations

Mathematical Optimization Problems for Particle Finite Element Analysis Applied to 2D Landslide Modeling

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

Overview of Native Chicken Breeds in Italy: Conservation Status and Rearing Systems in Use

The ongoing loss of domestic animal breeds around the world is occurring at an alarming rate. Thus, the registration and preservation of native breeds is of great importance. The aim of this study, which forms part of a conservation program, was to provide an overview of the conservation statuses of native Italian poultry breeds being reared by local breeders in Italy. The data collected by means of a census questionnaire demonstrate the low population sizes of these breeds in Italy and highlight the need for campaigns aimed at publicizing and promoting the benefits of native breeds with the goal of increasing population sizes. Identifying strategies to facilitate breeders’ access to pure breed birds is also essential, and would require collaborative efforts of university research centers, public entities, and breeders

Demographic, tumor and clinical features of clinical trials versus clinical practice patients with HER2-positive early breast cancer: results of a prospective study

Several randomized clinical trials (RCTs) have demonstrated the efficacy of trastuzumab-based adjuvant therapy in HER2-positive breast cancer (BC). However, RCT patients may not invariably be representative of patients routinely seen in clinical practice (CP). To address this issue, we compared the clinical and tumor features of RCT and CP patients with HER2-positive BC