1,721,003 research outputs found
Seismic vulnerability of shallow underground cavities in soft rock
No full textThe instability risk of underground cavities is issue of concern particularly for areas densely urbanized as the case of many historical centers in Italy. Among the possible causes of the cavity damages up to collapse, the proposed work considers a particular triggering factor that is the dynamic loading induced by an earthquake. Thus, the seismic vulnerability of shallow cavities in soft rock is addressed by proposing a methodology based on an extensive parametric two-dimensional finite element analysis. The proposed methodology is extended to a significant number of realistic cases, considering the effect of the variability of some predisposing and triggering factors on the cavity stability like roof thickness and cavity width, presence of overburden on the top of the rock layer, seismic signal intensity. The seismic vulnerability of the studied cases is assessed through the minimum Factor of Safety calculated during the whole length of the dynamic analysis. Finally, the results of the parametric study are rearranged into 'seismic stability charts for cavities in soft rock' proposed to be adopted as preliminary level of screening, to assess the seismic vulnerability of shallow underground cavities in soft rock. The results of screening enable to identify the critical zones that need a detailed analysis, in consideration of their possible interaction with above-ground structures, infrastructures and human activities
Vulnerabilità sismica di cavità sotterranee in roccia tenera
No full textLe cavità antropiche sotterranee poco profonde sono diffuse in molte aree urbanizzate di diverse regioni italiane, la cui stabilità rappresenta un potenziale rischio per edifici, infrastrutture e la popolazione stessa. Diverse sono le cause che possono inficiare la stabilità delle cavità: a partire dal loro scavo, la stabilità iniziale può peggiorare nel tempo a causa di diverse cause esterne (e.g. sovraccarichi imprevisti, importanti variazioni del livello di falda, etc...) che possono provocare danni progressivi fino al collasso globale. Anche le azioni sismiche rappresentano una fonte di instabilità per le cavità sotterranee come documentato da diversi studi di letteratura (Evangelista et al., 2016; Santo et al., 2011) e da osservazioni storiche (CFTI5Med, http://storing.ingv.it/cfti / cfti5 / (Guidoboni et al., 2019); CEDIT, http://www.ceri.uniroma1.it/index_cedit.html, (Fortunato et al., 2012)).
Nel presente lavoro viene focalizzata l’attenzione sul comportamento delle cavità in condizioni sismiche, proponendo una metodologia per valutarne la stabilità. La proposta è stata applicata ad uno specifico tipo di roccia tenera, ovvero il Tufo Giallo Napoletano in cui sono ricorrenti cavità antropiche scavate per diverse esigenze nel corso degli anni e con caratteristiche differenti (es. forma, dimensione, copertura, sovraccarichi), come documentato da diversi studi della letteratura tecnica (Evangelista et al., 2000; Evangelista et al., 2002; Scotto di Santolo et al., 2015a; Scotto di Santolo et al., 2015b; de Silva et al., 2018; de Silva et al., 2020)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The awakening of the dormant Mount Vettore fault (2016 Central Italy earthquake,Mw 6.6). Paleoseismic clues on its millennial silences
Full text linkThe Mount Vettore normal fault ruptured between August and October 2016, sourcing three earthquakes of Mw 6.2, 6.1, and 6.6. The first one caused the death of 299 people, while the entire sequence reached the highest macroseismic intensity levels in Italy since the catastrophic 1915 Fucino event (Mw 7.1). This fault was known to be one of the historically dormant faults of the Italian Apennines, and its sudden activation, not preceded by any foreshocks, has caught people and scientists off guards. We describe here the results from three new paleoseismic trenches opened across splays of the main antithetic fault that ruptured at surface on 30 October together with the 30‐km‐long Mount Vettore master fault. Data account for six surface faulting events since 9 ka, with a return time of 1.8 ± 0.3 kyr. The penultimate, probably stronger earthquake occurred in Late Roman times, perhaps in 443 AD, when also Rome suffered damage to its monumental buildings. Once again, paleoseismology turns out to be a powerful tool in seismic hazard assessment, especially for earthquakes that recur hundreds or thousands of years apart
A reappraisal of the 1599 earthquake in Cascia (Italian Central Apennines). Hypothesis on the seismogenic source
No full textIn this study, we investigate a little-known earthquake that struck Cascia and its environs (Central Italian Apennines) in 1599, causing 50 casualties and the destruction and abandonment of several settlements. As in current seismic catalogues the characterization of this event is based on the anonymous account of a single source, we conducted research using public and private archives and libraries that allow recovering many unpublished contemporary accounts of the earthquake. This information permitted a more detailed evaluation of the macroseismic effects and a doubling of the number of intensity datapoints, resulting in a more robust earthquake epicentral parameters. Next, we conducted a geological field survey within the newly defined mesoseismic area aimed at finding possible evidence of active tectonics, likely faults with indications of recent movements and with an attitude fitting both the 1599 highest intensity distribution and the regional stress field. We found evidence for Holocene surface faulting along the Cascia and Mount Alvagnano faults that we consider responsible for the 1599 earthquake, and possibly also for a twin event in 1979 and the much stronger Norcia earthquake in 1703
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effect of bedrock stiffness and thickness on numerical simulation of seismic site response. Italian case studies
No full textEvaluation of bedrock stiffness and thickness effect on ground motion modification represent a key-issue in the perspective of seismic risk reduction policy, since the maximum depth of site prospection generally does not extend down to the stiff bedrock location. Site conditions were identified from the Italian database of seismic microzonation studies. Simplified and realistic numerical models were adopted, i.e. extended down to the soft and stiff bedrock, respectively, in order to perform seismic site response analyses. Results indicate that simplified numerical model provides a quantification of the surface ground motion modification with an error generally equal to ±10% with respect to the realistic model. Hence, the evaluation of seismic performance of sites based on simplified numerical models represents a support tool for seismic risk management at large area
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