411 research outputs found
Late Holocene tectonic implications deduced from tidal notches in Leukas and Meganisi islands (Ionian Sea)
In this paper the tectonic behavior of Leukas and Meganisi islands (Ionian Sea) is examined through underwater research carried out in both islands. A possible Late Holocene correlation between coseismic subsidences is attempted and evidenced by submerged tidal notches in both islands. These subsidence events probably occurred after the uplift that affected the northernmost part of Leukas around 4 to 5ka BP. In conclusion, although the whole area was affected by a similar tectonic strain, certain coseismic events were only recorded in one of the two islands and in some cases they affected only part of the study are
Rapid Profiling of Marine Notches Using a Handheld Laser Distance Meter
A rapid, single-user profiling method for rocky shores is described. The Leica Disto D8 handheld laser distance meter
measures distance up to 100 m and inclination in 360 degrees. It automatically calculates horizontal distance and vertical elevation. Memory storage accommodates data for 30 measurement points, allowing easy plotting of shore profiles. This technique allows even inaccessible, dangerous, and overhanging cliff faces to be evaluated faithfully and within minutes. It is a major improvement over standard methods that often involve risky coasteering and climbing. Examples are given from marine notches in Thailand
Late Holocene shorelines deduced from tidal notches on both sides of the Ionian Thrust (Greece): Fiscardo Peninsula (Cephalonia) and Ithaca Island.
Fossil shorelines produced by recent co-seismic movements were identified throughasubmarine survey along the coasts of Ithaca and Fiscardo (Greece).In both areas a tidal notch-slightly submerged below present Mean Sea Level (MSL) was observed at various sites. This âmodernâ notch is known to have been submerged by the global sea-level rise during the 19th and 20th centuries. The depth after tide and air-pressure correction of the vertex of the âmodernâ notch (that owes its submergence to the current rapid sea level rise) was measured between -20 and -30±5cm at Fiscardo and between -36 and -45±6cm at Ithaca. This âmodernâ notch at the same depth on east and west sides of the Ionian Thrust suggests that both areas were not affected by the co-seismic vertical movements that occurred in 1953 (in the wider area). On the other hand, a greater depth in Ithaca could be an effect of co-seismic subsidence. Over the long term, the tectonic behavior of Ithaca differs from Fiscardo. At Ithaca no evidence of emergence was found and Holocene vertical movements have been only of subsidence: submerged fossil tidal notches were distinguished below MSL at about -40 (modern), -60, -75, -95, -106, -126, -150 and -220±6cm. On the East coast of Fiscardo peninsula impacts of ancient earthquakes have left some marks of emergence at about +18 and +44±5cm, and of submergence at about -25 (modern), -45, -60, -75, -82, -100 and -230cm, with even some evidence of past uplift and subsidence at the same sites
Paleogeographic Interpretation of a Peat Layer at Torson di Sotto (Lagoon of Venice, Italy)
Ein 3,3 m langer Kern aus dem zentralen Bereich der Lagune von Venedig enthielt eine Torflage zwischen 1,3 und 2,0 m unter dem mittleren Meeresspiegel. Pollenanalysen zeigen ein Vorherrschen von Quercus und Alnus und eine transgressive Phase an: der untere Teil des Torfes (nach 14C-Daten 1730±80 v.h.) ist in einem SĂŒĂwasser-Environment gebildet worden, der obere Teil (nach 14C-Daten 1140 + 80 v.h.) in einem brackischen. Foraminiferenanalysen zeigen an, daĂ der Transgression eine Regression vorangegangen ist. Die gesamte Abfolge enthĂ€lt von unten nach oben (Abb. 3): (1) ein oligohalines bis mesohalines Environment (von â3,3 bis â2,5 m) mit sehr zahlreichen Foraminiferen; (2) ein SĂŒĂwasser-Environment (von â2,5 bis â2,0 m); (3) die 0,7 m mĂ€chtige Torflage, die fortschreitend brackisch wird; (4) ein mesohalines Environment (oberhalb â1,3 m).Korrelationen mit benachbarten LokalitĂ€ten (Abb. 1) weisen darauf hin, daĂ vergleichbare Erscheinungen zu gleicher Zeit im Zentralteil der Lagune, aber nicht in ihrem Nordteil, aufgetreten sind. Diese Regressions-Transgressions-Abfolge wird auf eine Periode erhöhter NiederschlĂ€ge um das Ende der Römerzeit zurĂŒckgefĂŒhrt, die zur Ăberflutung und zu einer Verlagerung des Laufes zahlreicher FlĂŒsse gefĂŒhrt hat; dabei ist das ökologische Gleichgewicht dieses Marschengebietes zeitweilig verĂ€ndert worden. Im Verlauf der vergangenen 100 Jahre hat sich die Transgression beschleunigt, ĂŒberwiegend infolge anthropogener Eingriffe. Die âBarene" werden jetzt erodiert und verschwinden rasch (Abb. 2). Sie werden durch weite Meerwasserbecken eingenommen.researc
Decadal variability of European sea level extremes in relation to the solar activity
This study investigates the relationship between decadal changes in solar activity and sea level extremes along the European coasts and derived from tide gauge data. Autumn sea level extremes vary with the 11âyear solar cycle at Venice as suggested by previous studies, but a similar link is also found at Trieste. In addition, a solar signal in winter sea level extremes is also found at Venice, Trieste, Marseille, Ceuta, Brest, and Newlyn. The influence of the solar cycle is also evident in the sea level extremes derived from a barotropic model with spatial patterns that are consistent with the correlations obtained at the tide gauges. This agreement indicates that the link to the solar cycle is through modulation of the atmospheric forcing. The only atmospheric regional pattern that showed variability at the 11âyear period was the East Atlantic pattern
A flood damage allowance framework for coastal protection with deep uncertainty in sea-level rise
Future projections of Antarctic ice sheet (AIS) mass loss remain
characterized by deep uncertainty (i.e., behavior is not well understood or
widely agreed upon by experts). This complicates decisions on long-lived
projects involving the height of coastal flood protection strategies that seek
to reduce damages from rising sea levels. If a prescribed margin of safety does
not properly account for sea-level rise and its uncertainties, the
effectiveness of flood protection will decrease over time, potentially putting
lives and property at greater risk. We develop a flood damage allowance
framework for calculating the height of a flood protection strategy needed to
ensure that a given level of financial risk is maintained (i.e., the average
flood damage in a given year). The damage allowance framework considers
decision-maker preferences such as planning horizons, preferred protection
strategies (storm surge barrier, levee, elevation, and coastal retreat), and
subjective views of AIS stability. We use Manhattan (New York City)\textemdash
with the distribution of buildings, populations, and infrastructure fixed in
time\textemdash as an example to show how our framework could be used to
calculate a range of damage allowances based on multiple plausible AIS
outcomes. Assumptions regarding future AIS stability more strongly influence
damage allowances under high greenhouse gas emissions (Representative
Concentration Pathway [RCP] 8.5) compared to those that assume strong emissions
reductions (RCP2.6). Design tools that specify financial risk targets, such as
the average flood damage in a given year, allow for the calculation of avoided
flood damages (i.e., benefits) that can be combined with estimates of
construction cost and then integrated into existing financial decision-making
tools, like benefit-cost or cost-effectiveness analyses
Flood Protection in Venice under Conditions of Sea-Level Rise: An Analysis of Institutional and Technical Measures
It is widely acknowledged that in times of climate change loss of coastal resources and risk for human life can be minimized by implementing adaptation strategies. Such strategies need to encompass a balanced mix of non-structural (institutional) and structural (technical) measures based on sound scientific knowledge. This article discusses measures carried out to protect the city of Venice, Italy from flooding (locally known as âhigh waterâ), and reflects on their ability to anticipate a possible acceleration of sea-level rise as induced by climate change. It is based on scientific literature, legislative and policy documents of key institutions, reports and documents of organizations working on Venice issues, newspaper articles, and interviews. Our analysis shows that the synergic action of the hydraulic defense infrastructure under construction is in principle adequate to withstand a broad range of sea-level rise scenarios for the next 100 years. However, when the goal is to use these investments effectively major changes in the existing institutional arrangements will be required in the years to come. The Venice findings point out the difficulties and yet the importance of identifying and implementing both non-structural and structural measures to adapt to climate change
Tell formation processes as indicated from geoarchaeological and geochemical investigations at Xeropolis, Euboea, Greece
Xeropolis is a tell site on the island of Euboea, Greece just to the east of the village of Lefkandi, and was occupied from the Early Bronze Age to the Early Iron Age. Excavations in recent years have provided an opportunity to investigate site formation processes using geoarchaeological and geochemical techniques. Sediments derived from the tell on the southern side have been lost by coastal erosion whilst those on the north mantle the flanking slope. Of particular interest is a homogeneous and unstratified deposit of over 2 m which overlies the archaeology near the southern perimeter of the summit area. The soil structure as evident in thin sections indicates a high degree of bioturbation, probably stimulated by recent manuring and cultivation. The implication is that tillage erosion has had a major impact on the morphology as well as on the surface soils of the tell. Despite such reworking and redeposition of near surface materials, it is still possible from multi-element analysis to identify the geochemical distinctiveness of six archaeological contexts (pit, house, plaster floor, alley, road and yard); pits and floors have high loadings of all elements except Pb; in contrast pits and floors have the lowest elemental concentrations
Nomenclature for renal replacement therapy and blood purification techniques in critically ill patients: practical applications
This article reports the conclusions of the second part of a consensus expert conference on the nomenclature of renal replacement therapy (RRT) techniques currently utilized to manage acute kidney injury and other organ dysfunction syndromes in critically ill patients. A multidisciplinary approach was taken to achieve harmonization of definitions, components, techniques, and operations of the extracorporeal therapies. The article describes the RRT techniques in detail with the relevant technology, procedures, and phases of treatment and key aspects of volume management/fluid balance in critically ill patients. In addition, the article describes recent developments in other extracorporeal therapies, including therapeutic plasma exchange, multiple organ support therapy, liver support, lung support, and blood purification in sepsis. This is a consensus report on nomenclature harmonization in extracorporeal blood purification therapies, such as hemofiltration, plasma exchange, multiple organ support therapies, and blood purification in sepsis
Recommendations for motion correction of infant fNIRS data applicable to multiple data sets and acquisition systems
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