1,721,068 research outputs found
MORPHOTECTONIC ANALYSIS OF THE NEOTECTONIC AND ACTIVE FAULTS OF BEOTIA (CENTRAL GREECE), USING G.I.S. TECHNIQUES
Full text linkWe study the neotectonic regime and evolution of the central-eastern part of the Asopos River basin (Beotia, Central Greece) which is an area undergoing crustal extension. The main tools that were used in this research were a) field mapping of neotectonic and active normal faults and b) morphotectonic analysis of 59 catchments, which was carried out by GIS techniques. Our results include a) series of maps displaying the spatial variation of morphotectonic indices (sinuosity, asymmetry factor, valley-floor-to-height-ratio etc) and b) map of neotectonic fault segments with associated faultslip data. The morphotectonic analysis indicates that if normal faults in this area are active, they are capable of generating earthquakes with M >6.0
Predictive model of Arias Intensity and Newmark Displacement for regional scale evaluation of earthquake-induced landslide hazard in Greece
No full textDefining the possible scenario of earthquake-induced landslides, Arias Intensity is frequently used as shaking parameter, being considered the most suitable for characterizing earthquake impact, while Newmark's sliding-block model is widely used to predict the performance of natural slopes during earthquake shaking. In the present study we aim at providing tools for the assessment of the hazard related to earthquake-induced landslides at regional scale, by means of new empirical equations for the prediction of Arias Intensity along with an empirical estimator of coseismic landslide displacements based on Newmark’s model. The regression data, consisting of 205 strong motion recordings relative to 98 earthquakes, were subdivided into a training dataset, used to calculate equation parameters, and a validation dataset, used to compare the prediction performance among different possible functional forms and with equations derived from previous studies carried out for other regions using global and/or regional datasets. Equations predicting Arias Intensities expected in Greece at known distances from seismic sources of defined magnitude proved to provide more accurate estimates if site condition and focal mechanism influence can be taken into account. Concerning the empirical estimator of Newmark displacements, we conducted rigorous Newmark analysis on 267 one-component records yielding a dataset containing 507 Newmark displacements, with the aim of developing a regression equation that is more suitable and effective for the seismotectonic environment of Greece and could be used for regional-scale seismic landslide hazard mapping. The regression analysis showed a noticeable higher goodness of fit of the proposed relations compared to formulas derived from worldwide data, suggesting a significant improvement of the empirical relation effectiveness from the use of a regionally-specific strong-motion dataset
Postseismic displacement of the 1999 Athens earthquake retrieved by the Differential Interferometry by Synthetic Aperture Radar time series
No full textIn September 1999, a moderate (M(W) = 5.9) earthquake struck the Attica plain, causing unexpected and extensive damage to Athens and its population. In this work, we exploit the potential of multitemporal Differential Interferometry by Synthetic Aperture Radar (DInSAR) analysis, using about a hundred European Remote Sensing (ERS) 1/2 images to calculate the displacement time series from 1992 to 2002. This analysis allows us to clearly separate a strictly coseismic signal from a postseismic gradual subsidence, reaching a maximum value of about 3 cm in the following 2.5 years. We model this signal in terms of afterslip on the seismogenic fault. The afterslip distribution, retrieved by linear inversion, reflects the coseismic slip distribution and occurs mainly downdip of the area that ruptured during the main shock. The analysis of the static stress transfer suggests that the afterslip was triggered by the main shock, then it propagated aseismically through the fault plane. A partial overlap between the coseismic and aseismic slip area at the hypocentral region indicates that the 1999 rupture surface was not "healed'' at least until the date of the last postseismic image (April 2002). The results obtained with a time series approach for this moderate magnitude earthquake suggest that multitemporal DInSAR analysis should become an important methodology for the study of large earthquake ruptures. RI Salvi, Stefano/G-3905-201
Historical faulting in Aghios Konstantinos area (central Greece), based on archaeological indications
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Strike-slip motions in the Gulf of Sigacik (western Turkey): Properties of the 17 October 2005 earthquake seismic sequence
No full textGoing 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
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
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