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No full textINGVPublished4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale5.1. TTC - Banche dati e metodi macrosismiciope
Il database della pericolosità sismica in Italia
No full textNel periodo dal 2003 al 2007 due iniziative successive hanno portato alla realizzazione di stime aggiornate della pericolosità sismica in Italia: si tratta di progetti coordinati dall’INGV nell’ambito della convenzione quadro con il Dipartimento della Protezione Civile. Il primo progetto, sviluppato tra il 2003 e il 2004, ha portato alla realizzazione della mappa di riferimento della pericolosità sismica in Italia (MPS04; Gruppo di Lavoro MPS, 2004), il secondo ha portato al rilascio di ulteriori parametri, quali le accelerazioni spettrali, stime per diverse probabilità di eccedenza in 50 anni, disaggregazione, ecc.
La documentazione di queste attività è accessibile nei due siti web dedicati ai progetti, coordinati dalla Sezione di Milano-Pavia dell’INGV: rispettivamente http://zonesismiche.mi.ingv.it e http://esse1.mi.ingv.it, a cui si rimanda.
Per permettere una facile fruizione di tali dati è stata sviluppata un’applicazione specifica, con interfaccia webgis, descritta in (Martinelli e Meletti, 2008) ed accessibile all’indirizzo esse1 gis.mi.ingv.it.
La mole di dati prodotti (oltre 130 milioni di parametri relativi ad oltre 58.000 punti) ha reso indispensabile la creazione di un database opportunamente strutturato in modo da poterli utilizzare adeguatamente all’interno dell’applicazione stessa.
L’applicazione utilizza il database per produrre, oltre ai dati di pericolosità in forma tabellare e grafica, anche mappe tematiche di pericolosità. In particolare le mappe vengono prodotte “al volo” dalla libreria MapServer (http://mapserver.org/) con interrogazioni al database per i dati cartografici, ovvero per quanto riguarda i confini, il posizionamento dei nomi dei comuni e quello dei valori di pericolosità sulla mappa, quindi con un notevole scambio di dati.
In questo rapporto si presenta l’organizzazione del database della pericolosità sismica in Italia (2004-2008), sulla base del quale sono state elaborate anche le Norme Tecniche per le Costruzioni (NTC 2008).INGVPublished5.1. TTC - Banche dati e metodi macrosismiciope
Quadro geologico sull'evoluzione neogenico-quaternaria dell'Arco Calabro e zonazione sismotettonica dell'area dello Stretto di Messina
No full text
Main recent deformation and seismotectonics in the Central Mediterranean Region.
Full text linkLate Neogene-Quaternary tectonics in the Central Mediterranean region has been entirely controlled by the Africa-Adria-Europe plate interaction and by the passive subduction of the south-western margin of Adria. Presently the western, northern and eastern boundaries of Adria are outlined by first-order geological features (Apennines, Alps and Dinarides); the southern boundary, on the contrary, is still undefined and its location is controversial.
The reconstruction of the Neogene-Quaternary relative motion of Adria versus Europe is well constrained by the geometrical configuration of the Insubric indenter and by the geometry of the young thrust systems in the Southern Alps, Dinarides and Hellenides. The major structural features of these areas may be simultaneously justified by a counterclockwise rotation of Adria around a pole located in the Western Mediterranean Sea not far from the Corsica coast. The slip vectors obtained by such a rotation pole satisfactorily account for the overall kinematic processes along the external margin of Adria during Neogene-Quaternary times
Construction of a seismotectonic model: the case of Italy
No full textProcedures for constructing a seismotectonic model of Italy, designed to be used as a basis for hazard assessment, are described. The seismotectonic analysis has essentially been based on a GIS-aided cross-correlation of three data sets concerning: - the 3-D structural model of Italy and surrounding areas; - the space distribution of historical and present seismicity; - the kinematic model of the Central Mediterranean region, referred to the last 6 Ma and including the available information on the present-day plate motion and stress field. The seismicity pattern in the study area is controlled by a quite complex geodynamic framework which includes: - continent-continent convergence (Alps and Dinarides) with development of a neutral arc bordering the plate margins; - plate divergence across margins characterized by passive slab sinking (Northern Apennines and Calabrian Arc), with development of backarc basins (Northern Tyrrhenian Sea and Southern Tyrrhenian Sea) flanked by forelandward migrating thrust belt-foredeep systems; - plate divergence across a margin previously characterized by lithosphere sinking and afterwards discharged from the subducted slab (Southern Apennines), with development of quite peculiar rift processes within the inactive thrust belt; - transpression (Northern Sicily) due to the combined effect of plate convergence (Africa-Europe) and high-rate flexure-hinge retreat of an intervening plate (Adria microplate) with high angles between the respective slip vectors; - intraplate strain partition and fault activity (mainly combined strike-slip and thrust motions), possibly in correspondence of inverted structures. The results of the seismotectonic analysis are synthesized in a zonation of Italy in which every delimited zone corresponds to the surface projection of a kinematically-homogeneous segment of a seismogenic fault system. In Cornell-type hazard evaluations every polygon should be considered as a homogeneous source-zone, seat of randomly-distributed earthquakes. A homogeneous mechanical behaviour of an entire zone and a random earthquake-distribution within a single source zone obviously represent oversimplified assumptions since every zone includes one or more master-fault segments responsible for the greatest events in the area and several second-order associated faults responsible for the background minor seismicity. Therefore, major faults and background seismicity should be treated separately. Nevertheless, the oversimplified assumption of homogeneous seismic zones was the price the authors consciously paid to produce, in a reasonably short time, a homogeneous product relative to the entire national territory, suitable for earthquake hazard evaluation and for decisions regarding risk mitigation
Criteri e procedure per la compilazione di un inventario speditivo delle sorgenti potenziali di terremoti distruttivi finalizzato alla compilazine di una nuova mappa delle zone sismogenetiche per l'area italiana
No full textApplication of the Bakun Wentworth's Method for the Macroseismic Estimation of Parameters of Italian Earthquakes
No full textThe methodology proposed by Bakun and Wentworth (1997, Estimating earthquake location and magnitude from seismic intensity data, Bull. Seism. Soc. Am., 87, 1502-1521; hereinafter B&W) and calibrated with Italian data by Gomez Capera AA, D’Amico V, Meletti C (2008, Calibrating the Bakun-Wentworth’s method for the macroseismic estimation of earthquake parameters in Italy, this conference) was applied to the recently released macroseismic database of Italian earthquakes (DBMI07; http://emidius.mi.ingv.it/DBMI07). The database contains about 83000 intensity data points for 1430 earthquakes. In the time-interval 1900-2006, for the greater part of the earthquakes the instrumental determination (epicentral coordinates and magnitude) is available. Thus, the Bakun and Wentworth method (B&W) was applied to a large set of Italian earthquakes and the results compared with those obtained adopting the Boxer approach (Gasperini, P., Bernardini, F., Valensise, G., Boschi, E.,1999, Defining seismogenic sources from historical earthquake felt reports, Bull. Seismol. Soc. Am. 89, 94-110); epicentral determinations by both methods were then compared with the instrumental parameters.PublishedHersonissos, Creta island, Greece5.1. TTC - Banche dati e metodi macrosismiciope
Earthquake forecasting and hazard assessment: a preface
No full textForecasting potentially damaging future earthquakes and eruptions is a basic ( and expected) outcome of scientific research. Several kinds of forecast are presently performed by considering different combinations of geophysical, geological, historical information and the scientific debate focuses on feasibility of each kind of methodology and reliabilty of the relevant results
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