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211.
Niklas Leicher Biagio Giaccio Alison Pereira Sebastien Nomade Lorenzo Monaco Giorgio Mannella Paolo Galli Edoardo Peronance Danilo Mauro Palladino Gianluca Sottili Giovanni Zanchetta Bernd Wagner 《Boreas: An International Journal of Quaternary Research》2023,52(2):240-271
Thirty-two tephra layers were identified in the time-interval 313–366 ka (Marine Isotope Stages 9–10) of the Quaternary lacustrine succession of the Fucino Basin, central Italy. Twenty-seven of these tephra layers yielded suitable geochemical material to explore their volcanic origins. Investigations also included the acquisition of geochemical data of some relevant, chronologically compatible proximal units from Italian volcanoes. The record contains tephra from some well-known eruptions and eruptive sequences of Roman and Roccamonfina volcanoes, such as the Magliano Romano Plinian Fall, the Orvieto–Bagnoregio Ignimbrite, the Lower White Trachytic Tuff and the Brown Leucitic Tuff. In addition, the record documents eruptions currently undescribed in proximal (i.e. near-vent) sections, suggesting a more complex history of the major eruptions of the Colli Albani, Sabatini, Vulsini and Roccamonfina volcanoes between 313 and 366 ka. Six of the investigated tephra layers were directly dated by single-crystal-fusion 40Ar/39Ar dating, providing the basis for a Bayesian age–depth model and a reassessment of the chronologies for both already known and dated eruptive units and for so far undated eruptions. The results provide a significant contribution for improving knowledge on the peri-Tyrrhenian explosive activity as well as for extending the Mediterranean tephrostratigraphical framework, which was previously based on limited proximal and distal archives for that time interval. 相似文献
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213.
On 29 August, 2003, an intense convective storm system affected the Fella River basin, in the eastern Italian Alps, producing rainfall peaks of approximately 390 mm in 12 h. The storm triggered an unusually large debris flow in the ungauged Rio Cucco basin (0·65 km2), with a volume of approximately 78 000 m3. The analysis of the time evolution of the rainstorm over the basin has been based on rainfall estimates from radar observations and data recorded by a raingauge network. Detailed geomorphological field surveys, carried out both before and after the flood of August 2003, and the application of a distributed hydrological model have enabled assessment of flood response, estimation of erosion volumes and sediment supply to the channel network. The accounts of two eyewitnesses have provided useful elements for reconstructing the time evolution and the flow processes involved in the event. Liquid peak discharge estimates cluster around 20 m3 s?1 km?2, placing this event on the flood envelope curve for the eastern Italian Alps. The hydrological analysis has shown that the major controls of the flood response were the exceptional cumulated rainfall amount, required to exceed the large initial losses, and the large rainfall intensities at hourly temporal scales, required to generate high flood response at the considered basin scale. Observations on the deposits accumulated on the alluvial fan indicate that, although the dominant flow process was a debris flow, sheetflood also contributed to fan aggradation and fluvial reworking had an important role in winnowing debris‐flow lobes and redistributing sediment on the fan surface. This points out to the large discharge values during the recession phase of the flood, implying an important role for subsurface flow on runoff generation of this extreme flash flood event. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
214.
Stefania Pinna Antonio Pais Lorenzo Chessa Nicola Sechi Giulia Ceccherelli 《Estuarine, Coastal and Shelf Science》2009
In the Mediterranean region, herbivory appears to be a factor controlling the production of the endemic species Posidonia oceanica, which is mainly due to two main macroherbivores: the sea urchin Paracentrotus lividus, and the sparid fish Sarpa salpa. In this context the present study is a contribution in clarifying herbivory on P. oceanica by testing: 1) whether the abundance of grazing marks of the two herbivores is variable across different spatial scales, 2) whether spatial variation of P. lividus grazing marks and its density is consistent, 3) whether there is a dependence of the number of P. lividus grazing marks on its density, 4) whether the grazing of both macroherbivores, P. lividus and S. salpa, involves the entire leaf length, and 5) whether there is a dependence of the number of P. lividus grazing marks on the number of S. salpa grazing bites. 相似文献
215.
4DVAR data assimilation in the Intra-Americas Sea with the Regional Ocean Modeling System (ROMS) 总被引:2,自引:0,他引:2
B.S. Powell H.G. Arango A.M. Moore E. Di Lorenzo R.F. Milliff D. Foley 《Ocean Modelling》2008,23(3-4):130-145
We present the background, development, and preparation of a state-of-the-art 4D variational (4DVAR) data assimilation system in the Regional Ocean Modeling System (ROMS) with an application in the Intra-Americas Sea (IAS). This initial application with a coarse model shows the efficacy of the 4DVAR methodology for use within complex ocean environments, and serves as preparation for deploying an operational, real-time assimilation system onboard the Royal Caribbean Cruise Lines ship Explorer of the Seas. Assimilating satellite sea surface height and temperature observations with in situ data from the ship in 14 day cycles over 2 years from January 2005 through March 2007, reduces the observation-model misfit by over 75%. Using measures of the Loop Current dynamics, we show that the assimilated solution is consistent with observed statistics. 相似文献
216.
Angelo Camerlenghi Anna Del Ben Christian Hübscher Edy Forlin Riccardo Geletti Giuseppe Brancatelli Aaron Micallef Marco Saule Lorenzo Facchin 《Basin Research》2020,32(4):716-738
We conduct the seismic signal analysis on vintage and recently collected multichannel seismic reflection profiles from the Ionian Basin to characterize the deep basin Messinian evaporites. These evaporites were deposited in deep and marginal Mediterranean sedimentary basins as a consequence of the “salinity crisis” between 5.97 and 5.33 Ma, a basin-wide oceanographic and ecological crisis whose origin remains poorly understood. The seismic markers of the Messinian evaporites in the deep Mediterranean basins can be divided in two end-members, one of which is the typical “trilogy” of gypsum and clastics (Lower Unit – LU), halite (Mobile Unit – MU) and upper anhydrite and marl layers (Upper Unit – UU) traced in the Western Mediterranean Basins. The other end-member is a single MU unit subdivided in seven sub-units by clastic interlayers located in the Levant Basin. The causes of these different seismic expressions of the Messinian salinity crisis (MSC) appear to be related to a morphological separation between the two basins by the structural regional sill of the Sicily Channel. With the aid of velocity analyses and seismic imaging via prestack migration in time and depth domains, we define for the first time the seismic signature of the Messinian evaporites in the deep Ionian Basin, which differs from the known end-members. In addition, we identify different evaporitic depositional settings suggesting a laterally discontinuous deposition. With the information gathered we quantify the volume of evaporitic deposits in the deep Ionian Basin as 500,000 km3 ± 10%. This figure allows us to speculate that the total volume of salts in the Mediterranean basin is larger than commonly assumed. Different depositional units in the Ionian Basin suggest that during the MSC it was separated from the Western Mediterranean by physical thresholds, from the Po Plain/Northern Adriatic Basin, and the Levant Basin, likely reflecting different hydrological and climatic conditions. Finally, the evidence of erosional surfaces and V-shaped valleys at the top of the MSC unit, together with sharp evaporites pinch out on evaporite-free pre-Messinian structural highs, suggest an extreme Messinian Stage 3 base level draw down in the Ionian Basin. Such evidence should be carefully evaluated in the light of Messinian and post-Messinian vertical crustal movements in the area. The results of this study demonstrates the importance of extracting from seismic data the Messinian paleotopography, the paleomorphology and the detailed stratal architecture in the in order to advance in the understanding of the deep basins Messinian depositional environments. 相似文献
217.
Salvatore de Lorenzo Maddalena Michele Antonio Emolo Andrea Tallarico 《Journal of Seismology》2017,21(4):909-919
We investigate the elastic properties of the crust in the Gargano promontory, located in the northern part of the Apulia region (Southeastern Italy). Starting on April, 2013, a local-scale seismic network, composed of 12 short-period (1 Hz) seismic stations, was deployed on the Gargano promontory. Starting on October, 2013, the network was integrated with the recordings of nine seismic stations managed by the Italian Institute of Geophysics and Volcanology (INGV). The network recorded more than 1200 seismic events in about 15 months of data acquisition, with more than 700 small magnitude events localized in the Gargano promontory and surrounding areas. A Wadati-modified method allowed us to infer VP/VS = 1.73 for the area. A subset of about 400 events having a relatively smaller azimuthal gap (<200°) was selected to calibrate a 1D P-wave velocity model of the area, using the VELEST inversion code. The preferred model was obtained from the average of ten velocity models, each of them representing the inversion result from given initial velocity models, calibrated on previous geological and geophysical studies in the area. The results obtained under the assumption that VP could decrease with depth are unstable, with very different depths of the top of low-velocity layers. Therefore, the velocity model was obtained from the average of the results obtained under the assumption that VP cannot decrease with depth. A strong reduction of both RMS (about 58%) and errors on the location of the events was obtained with respect to the starting model. The final velocity model shows a strong velocity gradient in the upper 5 km of the crust and a small increase (from 6.7 to 7 km) at 30 km of depth. The epicenters of relocated events do not show clear correlations with the surface projection of known seismic faults. A cluster of the epicenters of the relocated events intersects almost perpendicularly the Candelaro fault trace at the surface. 相似文献
218.
Among the main invasive species, the wild boar (Sus scrofa) is the most responsible for soil degradation in Europe and many Italian regions. At the same time, the stable presence of this species in agricultural areas has induced a conflict with humans, causing economic losses, environmental degradation and also social issues. A clear quantification of the potential damages (in terms of soil bioturbation) of this species at large scale is, however, still obscure. The purpose of this research is to analyse the role of wild boars as a geomorphologic agent, presenting a general diagnostic framework regarding the geomorphic impact of this species, classifying and mapping potential sediment hotspots and their likely connection to rivers and road networks. Accordingly, a record of wild boar damage types is first presented, and their possible interaction with hydrological and geomorphological processes is described. Then, a pilot case study is discussed on mapping and quantifying wild boar damages in a hilly agricultural landscape located in northeast Italy. The wild boar damages were geolocalized using a geographical positioning system (GPS) in two years of intensive field campaigns among agricultural fields involved in wild boar damaging activities. For each damaged area (total 406), several measures of soil erosion depth were taken and the degradation surface of interest mapped for a total of 10 150 measures. The volume of removed soil was then estimated, considering the average depth of damages previously recorded. Finally, the Index of Connectivity was applied to provide a classification of the considered damages based on their connection to both river and road networks. The results indicate that the ongoing uncontrolled wild boar expansion may not affect crops only or be a risk for people, but can also increase soil erosion, with a potential connection to hydrographic networks and human infrastructures. © 2019 John Wiley & Sons, Ltd. 相似文献
219.
Andrés Iroumé Manuel Cartagena Luisa Villablanca Daniel Sanhueza Bruno Mazzorana Lorenzo Picco 《地球表面变化过程与地形》2020,45(9):1959-1973
The eco-hydrogeomorphic significance of large wood (LW) and its potential for increasing downstream hazards during extreme floods have been widely recognized. We used LW data collected for a 10-year period from the two low-order streams of Pichún (Pi) and Vuelta de Zorra (VZ) in Southern Chile to (a) determine if the abundance and dimensions of individual LW pieces change with time, (b) quantify wood load fluctuations during the 10-year period, and (c) assess the role of LW recruitment from the riparian forests to explain wood load fluctuations during the study period. Nine years after the first survey, the number of LW pieces in Pi and VZ diminished by 60 and 40%, respectively. Despite the reduction in these numbers, in Pi, the LW dimensions did not change significantly during the study. In VZ, the dimensions exhibited statistically significant differences, despite being within the same class. In both catchments, the LW load fluctuated during a 10-year period, but the drivers of change differed. Although tree toppling was the recruitment mechanism responsible for LW in both stream cases, the high wood load measured in Pi at the beginning of the study suggested massive tree recruitments before the first survey, followed by wood exports which were higher than inputs in the subsequent 10-year period. In VZ, LW load decreased during the first 9 years (mean annual rate of ~9.2 m3 year−1) and then increased by ~12.1 m3 year−1 in year 10. At VZ, the inputs consisted of single trees that were recruited from the riparian area and by upstream flotation, while exports occurred by downstream fluvial transport. Wood inputs and exports occurred asynchronously and led to LW load fluctuations at decadal and annual intervals. Land management and tree species thus exert a major influence on wood inventory and budget in streams. © 2020 John Wiley & Sons, Ltd. 相似文献
220.