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  • 11
    Electronic Resource
    Electronic Resource
    Reducibility of complex submanifolds of the complex euclidean space (2000)
    Springer
    Mathematische Zeitschrift 235 (2000), S. 251-257 
    Details
    ISSN: 0025-5874
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. Let M be a simply connected complex submanifold of $\mathbb{C}^N$ . We prove that M is irreducible, up a totally geodesic factor, if and only if the normal holonomy group acts irreducibly. This is an extrinsic analogue of the well-known De Rham decomposition theorem for a complex manifold. Our result is not valid in the real context, as it is shown by many counter-examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002090000139
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    Paper (German National Licenses)
    Fulltext
  • 12
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    A first appraisal of the seismogenic and tsunamigenic potential of the largest fault systems in the westernmost Mediterranean (2022)
    Elsevier
    Details
    Publication Date: 2024-02-20
    Description: Highlights • We identify the largest active fault systems of the Alboran Basin. • Characterization of faults is key for accurate tsunamigenic potential estimations. • Alboran largest fault systems may generate Mw 〉 7 earthquakes. • These earthquakes have the potential to generate significant tsunami waves approaching the coast. Abstract The westernmost Mediterranean hosts part of the plate boundary between the European and African tectonic plates. Based on the scattered instrumental seismicity, this boundary has been traditionally interpreted as a wide zone of diffuse deformation. However, recent seismic images and seafloor mapping studies support that most of the plate convergence may be accommodated in a few tectonic structures, rather than in a broad region. Historical earthquakes with magnitudes Mw 〉 6 and historical tsunamis support that the low-to-moderate instrumental seismicity might also have led to underestimation of the seismogenic and tsunamigenic potential of the area. We evaluate the largest active faults of the westernmost Mediterranean: the reverse Alboran Ridge, and the strike-slip Carboneras, Yusuf and Al-Idrissi fault systems. For the first time, we use a dense grid of modern seismic data to characterize the entire dimensions of the main fault systems, accurately describe the geometry of these structures and estimate their seismic source parameters. Tsunami scenarios have been tested based on 3D-surfaces and seismic source parameters, using both uniform and heterogeneous slip distributions. The comparison of our results with previous studies, based on limited information on the fault geometry and kinematics, indicates that accurate fault geometries and heterogeneous slip distributions are needed to properly assess the seismic and tsunamigenic potential in this area. Based on fault scaling relations, the four fault systems have a large seismogenic potential, being able to generate earthquakes with Mw 〉 7. The reverse Alboran Ridge Fault System has the largest tsunamigenic potential, being able to generate a tsunami wave amplitude greater than 3 m in front of the coasts of Southern Spain and Northern Africa.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 13
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    Self-Catalyzed Mannich-Type Reaction of Enolizable Cyclic 1,3-Dicarbonyls to Acyclic Nitrones: An Entry to Functionalized β-Enamino Diones (2013)
    American Chemical Society (ACS)
    Details
    Publication Date: 2013-04-05
    Description: The Journal of Organic Chemistry DOI: 10.1021/jo400331b
    Print ISSN: 0022-3263
    Electronic ISSN: 1520-6904
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society (ACS)
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    PAPER CURRENT
  • 14
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    The Making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18) (2021)
    Frontiers
    Details
    Publication Date: 2021-03-08
    Description: The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models’ weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH 〉5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH 〉3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH 〉1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning.
    Description: The NEAMTHM18 was prepared in the framework of the European Project TSUMAPS-NEAM (http://www.tsumaps-neam.eu/) funded by the mechanism of the European Civil Protection and Humanitarian Aid Operations with grant no. ECHO/SUB/2015/718568/PREV26 (https://ec.europa.eu/echo/funding-evaluations/financing-civil-protection-europe/selected-projects/probabilistic-tsunami-hazard_en). The work by INGV authors also benefitted from funding by the INGV-DPC Agreement 2012-2021 (Annex B2).
    Description: Published
    Description: 616594
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami
    Description: 2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto
    Description: 3SR TERREMOTI - Attività dei Centri
    Description: 5SR TERREMOTI - Convenzioni derivanti dall'Accordo Quadro decennale INGV-DPC
    Description: 3IT. Calcolo scientifico
    Description: 4IT. Banche dati
    Description: JCR Journal
    Keywords: probabilistic tsunami hazard assessment ; earthquake-generated tsunami ; hazard uncertainty analysis ; ensemble modeling ; maximum inundation height ; NEAM ; 05.08. Risk ; 03.02. Hydrology ; 04.06. Seismology ; 04.07. Tectonophysics ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
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    How much does geometry of seismic sources matter in tsunami modeling? A sensitivity analysis for the Calabrian subduction interface (2018)
    Details
    Publication Date: 2020-10-22
    Description: The geometry of seismogenic sources could be one of the most important factors concurring to control the generation and the propagation of earthquake-generated tsunamis and their effects on the coasts. Since the majority of potentially tsunamigenic earthquakes occur offshore, the corresponding faults are generally poorly constrained and, consequently, their geometry is often oversimplified as a planar fault. The rupture area of mega-thrust earthquakes in subduction zones, where most of the greatest tsunamis have occurred, extends for tens to hundreds of kilometers both down dip and along strike, and generally deviates from the planar geometry. Therefore, the larger the earthquake size is, the weaker the planar fault assumption become. In this work, we present a sensitivity analysis aimed to explore the effects on modeled tsunamis generated by seismic sources with different degrees of geometric complexities. We focused on the Calabrian subduction zone, located in the Mediterranean Sea, which is characterized by the convergence between the African and European plates, with rates of up to 5 mm/yr. This subduction zone has been considered to have generated some past large earthquakes and tsunamis, despite it shows only in-slab significant seismic activity below 40 km depth and no relevant seismicity in the shallower portion of the interface. Our analysis is performed by defining and modeling an exhaustive set of tsunami scenarios located in the Calabrian subduction and using different models of the subduction interface with increasing geometrical complexity, from a planar surface to a highly detailed 3D surface. The latter was obtained from the interpretation of a dense network of seismic reflection profiles coupled with the analysis of the seismicity distribution. The more relevant effects due to the inclusion of 3D complexities in the seismic source geometry are finally highlighted in terms of the resulting tsunami impact.
    Description: Unpublished
    Description: New Orleans
    Description: 1T. Deformazione crostale attiva
    Description: 5T. Modelli di pericolosità sismica e da maremoto
    Keywords: tsunami ; seismic source geometry ; 03.03. Physical ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 16
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    Importance of earthquake rupture geometry on tsunami modelling: the Calabrian Arc subduction interface (Italy) case study (2020)
    Oxford University Press
    Details
    Publication Date: 2020-10-16
    Description: The behaviour of tsunami waves at any location depends on the local morphology of the coasts, the encountered bathymetric features, and the characteristics of the source. However, the importance of accurately modelling the geometric properties of the causative fault for simulations of seismically induced tsunamis is rarely addressed. In this work, we analyse the effects of using two different geometric models of the subduction interface of the Calabrian Arc (southern Italy, Ionian Sea) onto the simulated tsunamis: a detailed 3-D subduction interface obtained from the interpretation of a dense network of seismic reflection profiles, and a planar interface that roughly approximates the 3-D one. These models can be thought of as representing two end-members of the level of knowledge of fault geometry. We define three hypothetical earthquake ruptures of different magnitudes (Mw 7.5, 8.0, 8.5) on each geometry. The resulting tsunami impact is evaluated at the 50-m isobath in front of coastlines of the central and eastern Mediterranean. Our results show that the source geometry imprint is evident on the tsunami waveforms, as recorded at various distances and positions relative to the source. The absolute differences in maximum and minimum wave amplitudes locally exceed one metre, and the relative differences remain systematically above 20 per cent with peaks over 40 per cent. We also observe that tsunami energy directivity and focusing due to bathymetric waveguides take different paths depending on which fault is used. Although the differences increase with increasing earthquake magnitude, there is no simple rule to anticipate the different effects produced by these end-member models of the earthquake source. Our findings suggest that oversimplified source models may hinder our fundamental understanding of the tsunami impact and great care should be adopted when making simplistic assumptions regarding the appropriateness of the planar fault approximation in tsunami studies. We also remark that the geological and geophysical 3-D fault characterization remains a crucial and unavoidable step in tsunami hazard analyses.
    Description: Published
    Description: 1805–1819
    Description: 3T. Sorgente sismica
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 17
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    The COVID-19 Infection in Italy: A Statistical Study of an Abnormally Severe Disease (2021)
    MDPI
    Details
    Publication Date: 2021-03-03
    Description: We statistically investigate the Coronavirus Disease 19 (COVID-19) pandemic, which became particularly invasive in Italy in March 2020. We show that the high apparent lethality or case fatality ratio (CFR) observed in Italy, as compared with other countries, is likely biased by a strong underestimation of the number of infection cases. To give a more realistic estimate of the lethality of COVID-19, we use the actual (March 2020) estimates of the infection fatality ratio (IFR) of the pandemic based on the minimum observed CFR and analyze data obtained from the Diamond Princess cruise ship, a good representation of a "laboratory" case-study from an isolated system in which all the people have been tested. From such analyses, we derive more realistic estimates of the real extent of the infection as well as more accurate indicators of how fast the infection propagates. We then isolate the dominant factors causing the abnormal severity of the disease in Italy. Finally, we use the death count-the only data estimated to be reliable enough-to predict the total number of people infected and the interval of time when the infection in Italy could end.
    Description: Published
    Description: 1564
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: COVID-19 ; epidemic in Italy ; statistical forecast
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 18
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    Effect of Shallow Slip Amplification Uncertainty on Probabilistic Tsunami Hazard Analysis in Subduction Zones: Use of Long-Term Balanced Stochastic Slip Models (2020)
    Springer
    Details
    Publication Date: 2021-04-20
    Description: The complexity of coseismic slip distributions influences the tsunami hazard posed by local and, to a certain extent, distant tsunami sources. Large slip concentrated in shallow patches was observed in recent tsunamigenic earthquakes, possibly due to dynamic amplification near the free surface, variable frictional conditions or other factors. We propose a method for incorporating enhanced shallow slip for subduction earthquakes while preventing systematic slip excess at shallow depths over one or more seismic cycles. The method uses the classic k−2 stochastic slip distributions, augmented by shallow slip amplification. It is necessary for deep events with lower slip to occur more often than shallow ones with amplified slip to balance the long-term cumulative slip. We evaluate the impact of this approach on tsunami hazard in the central and eastern Mediterranean Sea adopting a realistic 3D geometry for three subduction zones, by using it to model ~ 150,000 earthquakes with 𝑀𝑤 from 6.0 to 9.0. We combine earthquake rates, depth-dependent slip distributions, tsunami modeling, and epistemic uncertainty through an ensemble modeling technique. We found that the mean hazard curves obtained with our method show enhanced probabilities for larger inundation heights as compared to the curves derived from depth-independent slip distributions. Our approach is completely general and can be applied to any subduction zone in the world.
    Description: Published
    Description: 1497–1520
    Description: 3T. Sorgente sismica
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 19
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    Probabilistic Tsunami Hazard Analysis: High Performance Computing for Massive Scale Inundation Simulations (2021)
    Frontiers
    Details
    Publication Date: 2021-01-14
    Description: Probabilistic Tsunami Hazard Analysis (PTHA) quantifies the probability of exceeding a specified inundation intensity at a given location within a given time interval. PTHA provides scientific guidance for tsunami risk analysis and risk management, including coastal planning and early warning. Explicit computation of site-specific PTHA, with an adequate discretization of source scenarios combined with high-resolution numerical inundation modelling, has been out of reach with existing models and computing capabilities, with tens to hundreds of thousands of moderately intensive numerical simulations being required for exhaustive uncertainty quantification. In recent years, more efficient GPU-based High-Performance Computing (HPC) facilities, together with efficient GPU-optimized shallow water type models for simulating tsunami inundation, have now made local long-term hazard assessment feasible. A workflow has been developed with three main stages: 1) Site-specific source selection and discretization, 2) Efficient numerical inundation simulation for each scenario using the GPU-based Tsunami-HySEA numerical tsunami propagation and inundation model using a system of nested topo-bathymetric grids, and 3) Hazard aggregation. We apply this site-specific PTHA workflow here to Catania, Sicily, for tsunamigenic earthquake sources in the Mediterranean. We illustrate the workflows of the PTHA as implemented for High-Performance Computing applications, including preliminary simulations carried out on intermediate scale GPU clusters. We show how the local hazard analysis conducted here produces a more fine-grained assessment than is possible with a regional assessment. However, the new local PTHA indicates somewhat lower probabilities of exceedance for higher maximum inundation heights than the available regional PTHA. The local hazard analysis takes into account small-scale tsunami inundation features and non-linearity which the regional-scale assessment does not incorporate. However, the deterministic inundation simulations neglect some uncertainties stemming from the simplified source treatment and tsunami modelling that are embedded in the regional stochastic approach to inundation height estimation. Further research is needed to quantify the uncertainty associated with numerical inundation modelling and to properly propagate it onto the hazard results, to fully exploit the potential of site-specific hazard assessment based on massive simulations.
    Description: Published
    Description: 591549
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 20
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    Rupture dynamics along bimaterial interfaces: a parametric study of the shear-normal traction coupling (2018)
    Details
    Publication Date: 2021-04-20
    Description: Earthquake ruptures often develop along faults separating materials with dissimilar elastic properties. Due to the broken symmetry, the propagation of the rupture along the bimaterial interface is driven by the coupling between interfacial sliding and normal traction pertur- bations. We numerically investigate in-plane rupture growth along a planar interface, under slip weakening friction, separating two dissimilar isotropic linearly elastic half-spaces, and we perform a parametric study of the classical Prakash–Clifton regularization, for different material contrasts. In particular the mesh-dependence and the regularization-dependence of the numerical solutions are analysed in this parameter space. When the regularization involves a slip-rate dependent relaxation time, a characteristic sliding distance is identified below which numerical solutions no longer depend on the regularization parameter, that is, they are phys- ically well-posed solutions. Such regularization provides an adaptive high-frequency filter of the slip-induced normal traction perturbations, following the dynamic shrinking of the dissi- pation zone during the acceleration phase. In contrast, a regularization involving a constant relaxation time leads to numerical solutions that always depend on the regularization parameter since it fails in adapting to the shrinking of the process zone. Dynamic regularization is further investigated using a non-local regularization based on a relaxation time that depends on the dynamic length of the dissipation zone. Such reformulation is shown to provide similar results as the dynamic timescale regularization proposed by Prakash–Clifton when the slip rate is replaced by the maximum slip rate along the sliding interface. This leads to the identification of a dissipative length scale associated with the coupling between interfacial sliding and nor- mal traction perturbations, together with a scaling law between the maximum slip rate and the dynamic size of the process zone during the rupture propagation. Dynamic timescale reg- ularization provides mesh-independent and physically well-posed numerical solutions during the acceleration phase towards an asymptotic speed. When generalized Rayleigh wave does not exist, numerical solutions are shown to tend towards an asymptotic velocity higher than the slowest shear wave speed. When the generalized Rayleigh wave speed exists, numerical solutions tend towards this velocity becoming noisier and noisier as the rupture progresses. In this regime regularization dependent, unstable finite-size pulses may be generated.
    Description: Published
    Description: 48–67
    Description: 2T. Sorgente Sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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