1,721,100 research outputs found
Numerical simulation of earthquake recurrence time for selected fault. Public deliverable report, DPC-INGV-S2 Project “Constraining observations into Seismic Hazard”, 36 pp.
No full textAccounting for spatial correlation in the empirical scoring of probabilistic seismic hazard estimates
No full textA procedure is here proposed to score probabilistic seismic hazard estimates provided by ergodic models by a comparison with accelerometric observations available during a control period. The procedure allows accounting for the potential bias induced by spatial correlation of hazard estimates due to the use of ground motion prediction equations in the modeling. Since this bias depends on the specific topological features of the studied system (relative positions of seismic sources and accelerometric control sites), numerical simulations are considered to correct it. An application of the above procedure is proposed for Italy where some probabilistic seismic hazard estimates have been provided in the last years, and where 76 accelerometric sites have been operating for more than 25 years. It is shown that, at least as the case study concerns, the amount of spatial correlation in the hazard estimates is relatively weak, it depends on the GMPE used in computations and increases with the exceedance probabilities and with the period of the acceleration response spectrum
Zone sismiche e pericolosità in Italia: dalle norme regionali alla comunicazione del rischio
No full textLa classificazione simica in Italia è uno strumento per la gestione del territorio affidato negli ultimi decenni alle Regioni. Attualmente essa viene impiegata quale strumento di verifica amministrativa sulle strutture di recente costruzione o riadeguate ai sensi della normativa antisismica. Per la sua genesi ed evoluzione nel tempo, però, essa risulta alle volte incoerente con la fase di progettazione, e non sempre assicura un’imparziale funzione di controllo. Nel presente lavoro abbiamo analizzato come il significato della zonazione si sia modificato nel corso del tempo, facendosi interprete e strumento di elaborazioni scientifiche aggiornate ma, d’altro canto, assoggettandosi alla eterogeneità di atti normativi regionali. Abbiamo quantificato le differenze di valori di pericolosità sismica esistenti per comuni attribuiti alle medesime zone sismiche, all’interno di ciascuna regione e fra le varie regioni. Solo una revisione omogenea dei criteri di classificazione sulla base dei valori di pericolosità sismica potrà portare alla creazione di uno strumento amministrativo più obiettivo e di equo utilizzo. Infine, poiché la classificazione è spesso utilizzata impropriamente come indicatore del livello sismico di un comune, oscillando tra il significato di pericolosità e quello di rischio, è auspicabile che a fini comunicativi vengano introdotti nuovi strumenti che consentano ai cittadini una percezione più adeguata della componente naturale del rischio sismico.Published15-313T. Pericolosità sismica e contributo alla definizione del rischioN/A or not JCRope
Induzione della crescita ovarica di Procambarus clarkii (Girard, 1852) mediante silenziamento dell'ormone gonado-inibitorio
No full textAttenuating intensities
No full textThe study presents a methodology in which fractile distances for a given macroseismic intensity are used as a point measure on which to do attenuation characterization. The use of statistically derived distances expected not to be exceeded at a given probability avoids ambiguous definition of isoseismal radii, and consequent mis- interpretation of attenuation parameters with a physical content. The utility and definiteness of such a fractile distance is evident when treating many earthquakes, of different magnitudes and for which the macroseismic data-sets are of different sizes. The methodology is applied to 55 Italian earthquakes of the last four centuries, with epicentral intensity ranging from VII to XI MCS. Propagation properties in volcanic districts are peculiar, with a rapid decay of observed intensity from the epicentre. The attenuation properties of the other crustal en- vironments are not clcarly correlated with the geodynamic domain; the earthquakes show a mean behaviour that appears to depend on relatively homogeneous conditions of propagation. Source depth, tectonic style and finiteness of the source are not addressed because only macroseismic surveying had been applied to most of the earthquakes, and they cannot be linked to surficial fault ruptures. The study is intended to provide mean attenuations that can be used in probabilistic seismic hazard studies; the variabiljty of individual earthquake attenuations for a region introduces the need to use different parameters in future deterministic earthquake scenarios.JCR Journalope
LASSCI2009.2: layered earthquake rupture forecast model for central Italy, submitted to the CSEP project
No full textThe Collaboratory for the Study of Earthquake Predictability (CSEP) selected Italy as a testing region for probabilistic earthquake forecast models in October, 2008. The model we have submitted for the two medium-term forecast periods of 5 and 10 years (from 2009) is a time-dependent, geologically based, earthquake rupture forecast that is defined for central Italy only (11-15 ̊ E; 41-45 ̊ N). The model took into account three separate layers of seismogenic sources: background seismicity; seismotectonic provinces; and individual faults that can produce major earthquakes (seismogenic boxes). For CSEP testing purposes, the background seismicity layer covered a range of magnitudes from 5.0 to 5.3 and the seismicity rates were obtained by truncated Gutenberg-Richter relationships for cells centered on the CSEP grid. Then the seismotectonic provinces layer returned the expected rates of medium-to-large earthquakes following a traditional Cornell-type approach. Finally, for the seismogenic boxes layer, the rates were based on the geometry and kinematics of the faults that different earthquake recurrence models have been assigned to, ranging from pure Gutenberg- Richter behavior to characteristic events, with the intermediate behavior named as the hybrid model. The results for different magnitude ranges highlight the contribution of each of the three layers to the total computation. The expected rates for M > 6.0 on April 1, 2009 (thus computed before the L'Aquila, 2009, Mw = 6.3 earthquake) are of particular interest. They showed local maxima in the two seismogenic-box sources of Paganica and Sulmona, one of which was activated by the L'Aquila earthquake of April 6, 2009. Earthquake rates as of August 1, 2009, (now under test) also showed a maximum close to the Sulmona source for Mw ~ 6.5; significant seismicity rates (10-4 to 10-3 in 5 years) for destructive events (magnitude up to 7.0) were located in other individual sources identified as being capable of such earthquakes in the central part of this area of the Apennines.Published3T. Pericolosità sismica e contributo alla definizione del rischioN/A or not JCRope
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