1,720,967 research outputs found
Regional-scale seafloor mapping and geohazard assessment. The experience from the Italian project MaGIC (Marine Geohazards along the Italian Coasts)
No full textRecent developments in seafloor imaging and mapping techniques greatly improved our capability of identifying marine geohazards affecting continental margins. Geomorphic features can be detected in great detail by high-resolution multibeam imaging and regarded as geohazard indicators; the most common include slide scars and deposits, canyon headscarps and steep erosional flanks, fault-related seafloor unevenness, mud volcanoes, pockmarks, gravity flow deposits, erosional scours and bedforms indicating sediment mobility at diverse temporal/spatial scale. These processes are widespread on Italian continental margins and are potential indicators of geohazard for human settlements and infrastructures in the offshore and coastal zones. The national Project MaGIC (Marine Geohazards along the Italian Coasts) aims at documenting potential geohazards based on the acquisition of high-resolution multibeam bathymetry and on the production of maps of the geohazard-related geomorphic features for most of the Italian continental margins. With reference to this issue, we discuss some of the most frequent problems dealing with reconnaissance, interpretation and cartographic representation of geohazard-related geomorphic features at a regional scale
The Italian MaGIC Project: A first-order geohazard assessment by means of regional seafloor mapping
No full textOver the past decades interest for marine geohazard assessment has rapidly grown up, driven by the increasing exploitation of natural resources, the emplacement of bottom-lying structures (cables and pipelines) and by the development of coastal areas, whose infrastructures increasingly protrude to the sea. At the same time, recent advances in seafloor mapping techniques have greatly improved our knowledge of geomorphic features that can be regarded as geohazard indicators, such as volcanic vents, slide scars, canyon headscarps, and fault-related seafloor unevenness. The national Project MaGIC (Marine Geohazards along the Italian Coast) is aimed at depicting potential geohazards based on the acquisition of highresolution bathymetry and on the production of maps of the geohazard -related geomorphic features for most of the Italian continental margins
Middle-Upper Pleistocene record of 100-ka depositional cycles on the Southern Tuscany continental margin (Tyrrhenian Sea, Italy). Sequence architecture and margin growth pattern
No full textFive unconformity-bounded depositional sequences have been seismically defined on the Tyrrhenian margin offshore Southern Tuscany, Italy. The set of sequences encompasses a ~ 500. ka interval, each sequence recording a ~ 100-ka orbitally-driven climate-eustatic cycle. Similarly to most of Quaternary continental margins, sequences on the Southern Tuscany margin show an overall regressive motif reflecting shelf sediment progradation basically during the prolonged phases of sea level fall that characterise the Middle-Upper Pleistocene 100-ka cyclicity. On seismic profiles, however, progradational units within each sequence display a variable clinoform geometry, interpreted as a record of the alternation of highstand, falling and lowstand intervals within 100-ka. cycles. The observed geometric variability is thus used as a key for separating systems tracts otherwise merging into a general progradational/regressive sedimentary body composing the bulk of each sequence. On a longer term, the interplay between sea level changes modulated by 100-ka. cycles and regional subsidence controls the stratigraphic architecture and the growth pattern of the continental margin. This effect is documented by the overall aggradational/retrogradational stacking pattern of sequences, superimposed on shelf margin progradation and reflecting the renewal of accommodation space landward of the shelf margin and its exploitation at each cycle. © 2012 Elsevier B.V
High-resolution morpho-bathymetric imaging of the Messina Strait (Southern Italy). New insights on the 1908 earthquake and tsunami
No full textThe 28 December, 1908 Reggio Calabria and Messina earthquake (named after the two most damaged cities on the coasts of Messina Strait) was one of the strongest (MW 7.1) ever to occur in Italy, and was also followed by a tsunami that severely impacted the coasts of the Strait. Although there is general agreement that its epicentre is located offshore in the Messina Strait, the source fault has never been detected; a century-long question is therefore pending on the source of both the 1908 earthquake and tsunami. Within the ongoing debate on this subject, little attention has been given, so far, to morphological insights from high resolution bathymetric (multibeam) data, particularly as regarding the evidence of faults affecting the seafloor and the question of whether a submarine landslide may had been the cause of the tsunami. We aim to address this issue by presenting the results of a morpho-bathymetric study in the Messina Strait and surroundings, investigated by means of high-resolution swath bathymetry. The primary morpho-structural feature in this area is the axial channel of the Messina Canyon, towards which flow several tributary canyons that incise the steep continental slope on the Calabrian and Sicilian margins. These canyons carve deeply into a very narrow (almost lacking) continental shelf and merge laterally forming a continuous erosional margin rimming the Messina Strait. This giant, composite canyon environment is the locus of intense erosional and depositional processes that superimpose on active tectonic deformation, resulting in a complex geomorphology that hinders the distinction between tectonic and sedimentary features. Seafloor ruptures that may be linked to fault systems compatible with the source of the 1908 earthquake and tsunami could not be identified based from our morpho-bathymetric analysis; however, we provide evidence of several geomorphic features indicative of tectonic deformation in the Messina Strait, define the presence and distribution of submarine landslides, and evaluate their possible role as tsunami sources. © 2013 Elsevier B.V
Coastal and Submarine Landslides in the Tectonically-Active Tyrrhenian Calabrian Margin (Southern Italy): Examples and Geohazard Implications
No full textHigh-resolution multibeam bathymetry is used as basis for detecting instability processes on the Tyrrhenian margin offshore Calabria (Italy). Among the many evidence at different spatial scale, we focus on selected cases that may represent a potential geohazard because of their scale, shallow/proximal location and state of activity. These include failures along coastal cliffs and canyon headwalls indenting narrow shelves. Coastal rocky failures impacting shallow water offshore Scilla and Palmi retain significant tsunamigenic potential, as proved by the 1783 Scilla event. Slide scars at canyon headwalls offshore Bagnara Calabra and Gioia Tauro indicate retrogressive failure active at water depth <10 m, just few hundreds of meters from the coast and the settlements and infrastructures there present. Geohazard related to these features is therefore relevant as testified by the failure induced during construction of the Gioia Tauro harbour in 1977
Preliminary interpretation of high resolution 3D seismic data from offshore Mt. Etna, Italy
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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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