1,721,052 research outputs found
Last 100 ka tephrostratigraphic record of Mount Etna.
No full textFor thousands of years man has marvelled at the gigantic structure that makes up Mt. Etna, the largest active volcano in Europe, and has lived side by side with the mountain, which despite its intense eruptive activity has always been considered a "friendly giant."
After the Second World War, with its frequent but non life-threatening eruptions, Mt. Etna represented an ideal location for volcanological research for the national and international scientific community. Numerous scientists from Belgium, Germany, France, the United Kingdom, and the United States of America have taken part in volcanological research aimed at understanding the volcano.Published77-891V. Storia eruttiva3V. Proprietà dei magmi e dei prodotti vulcanic
Last 100 ka tephrostratigraphic record of Mount Etna.
No full textFor thousands of years man has marvelled at the gigantic structure that makes up Mt. Etna, the largest active volcano in Europe, and has lived side by side with the mountain, which despite its intense eruptive activity has always been considered a "friendly giant."
After the Second World War, with its frequent but non life-threatening eruptions, Mt. Etna represented an ideal location for volcanological research for the national and international scientific community. Numerous scientists from Belgium, Germany, France, the United Kingdom, and the United States of America have taken part in volcanological research aimed at understanding the volcano.Published77-891V. Storia eruttiva3V. Proprietà dei magmi e dei prodotti vulcanic
Age of the Valle del Bove formation and chronology of the post-collapse flank eruptions, Etna volcano (Italy)
No full textTephrostratigraphy of the last 2 ka activity of Etna volcano
No full textStratigraphic and facies analysis, conducted in the 90’s, on the pyroclastic successions blanking the Etna volcano flanks permitted the reconstruction of the last 100 ka tephrostratigraphic record of the volcano explosive activity. During the Holocene, several strong explosive events occurred, including a basaltic plinian eruption in 122 BC. However, the historical period lacks of detailed investigation on the Etna pyroclastic succession, therefore, we focused our research on this period.
We started with an accurate field work aimed to the description of the pyroclastic deposits cropping out prevalently on the NE flank of the volcano. This tephra succession is characterized by alternations of ash layers, scoriaceous lapilli rich horizons and varicoloured tuffs attributed to a phreatomagmatic activity. Several yellowish volcanoclastic horizons, sometimes rich in charcoal, separate the tephra layers, indicating non-eruptive periods between the eruptions.
We compiled 7 tephrostratigraphic sections having as common base the marker bed “FG” of the 122 BC plinian eruption and we collected 62 tephra samples and 7 charcoals for laboratories analysis. In particular, grainsize, component, chemical and petrographic analysis were carried out on tephra samples, whereas the charcoals were sent to Beta Analytics, Miami, for 14C radiometric analysis. The whole data set permitted us to correlate the tephra layers and to recognised 16 tephrostratigraphic units.
The integration of the radiometric data with historical chronicles regarding the past activity of Etna, allow us to attribute some tephrostratigraphic units to 7 Etna historic eruptions whose distal deposit had never been found before. These eruptions could be considered as belonging to class B of Branca and Del Carlo (2005), characterised by prevalent intense explosive activity producing copious tephra fallouts, as happened during the 2001 and 2002-2003 eruptive events.PublishedPuerto de la Cruz, Tenerife3.5. Geologia e storia dei vulcani ed evoluzione dei magmiope
La fotogrammetria digitale applicata in aree vulcaniche: l’area sommitale del monte Etna
No full textLe aree vulcaniche sono frequentemente soggette a variazioni topografiche dovute a colate di lava od eventi di frana collegati all'attività eruttiva. La disponibilità di cartografia aggiornata e dettagliata contribuisce a realizzare analisi di tipo quantitativo che contribuiscono alla conoscenza ed al monitoraggio dei fenomeni effusivi. La topografia è un importante parametro di input per i codici di simulazione che vengono adottati per costruire mappe di hazard e valutare l'evoluzione temporale dei flussi lavici. In questo lavoro viene presentato l'aggiornamento della topografia della parte sommitale dell'Etna estratta da un volo fotogrammetrico realizzato nell'agosto 2004. Quest'area è stata infatti interessata da diverse eruzioni effusive tra il 1998, anno di aggiornamento della Carta Tecnica Provinciale di Catania (CTP-1998), e il 2004. Vengono inoltre presentate alcune prove di editing del DTM 2004 per eliminare la vegetazione. La procedura di estrazione automatica del DTM può infatti portare, in aree ricoperte da fitta vegetazione, ad una rappresentazione errata delle caratteristiche morfologiche della superficie. Questo lavoro presenta, infine, il calcolo del volume di un flusso lavico emesso nel 2002 sul versante NE. Questo è stato ottenuto dal confronto tra il DTM 2004 e il DTM estratto dalla CTP-1998 dopo aver valutato l'ondulazione del geoide nella zona in esame. I due DTM si riferiscono, infatti, a due diversi sistemi di riferimento altimetrici: il 2004 si basa sulle quote ellissoidiche mentre il 1998 utilizza quote geoidich
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
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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