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31.
Pietro Mosca Riccardo Polino Sergio Rogledi Massimo Rossi 《International Journal of Earth Sciences》2010,99(4):833-849
Alps and Apennines are juxtaposed within an approximately 100 km-wide area covered by the Upper Eocene to Miocene successions
of the Tertiary Piedmont Basin. The Upper Eocene–Oligocene evolution of this area was characterized to the north and west
by the propagation of the SE-verging Southalpine thrust-fold belt that can be traced from the Po Plain subsurface until the
Torino Hill-Saluzzese area, and to the south by a high-angle, broadly E–W oriented megashear zone that led to the juxtaposition
of different crustal levels and controlled the development of a mosaic of partly independent sub-basins. Since the latest
Oligocene the N-verging Apenninic tectonics prevailed in the collisional system and the Tertiary Piedmont Basin evolved as
a wide thrust-top basin, bounded to the north by the N-verging Monferrato arc and characterized by a tectono-sedimentary evolution
recording changes of subsidence and shift of depocentres in relation to crustal structures. 相似文献
32.
Franco Mantovani Francisco Javier Gracia Pietro Domenico de Cosmo Andrea Suma 《Landslides》2010,7(1):69-74
This paper presents the preliminary results of a geomorphological survey of the Olvera area (Cadiz province, Betic Ranges,
Spain) and the use of the Geographic Information System (GIS) Open Source (OS) software plus Database Management System (DBMS)
for making available and distributing the landslide data over the Web. In the geomorphologic survey, different landforms have
been identified in the area, including structural, anthropogenic, fluvial, karst, and slope forms. In particular, the majority
of the slope forms are complex (from topple to rotational slides and falls), but there are also minor forms like debris flows
and mudslides. To manage geomorphological data, an Open Source GIS was used, which contained the following components: QuantumGIS,
System for Automated Geoscientific Analyses (SAGA), GIS and Geographic Resources Analysis Support System (GRASS), GIS for
Digital Elevation Model (DEM) generation. A key aim was to make the project-derived data available over the Web. This was
achieved using MapServer which allows for the representation of the derived geospatial data with pMapper providing the graphical
Web interface. Our study highlights the process dynamics of run-off erosion in Olvera derived through the use of advanced
computer-based mapping tools. The resulting map products and interpretations are available via the Internet. To date, derivative
maps have been produced to improve maintenance of roads and transport and of the construction of new infrastructure. 相似文献
33.
Antonio Bucci Gino Naclerio Vincenzo Allocca Pietro Celico Fulvio Celico 《水文研究》2011,25(12):1866-1873
The Ischia hydrothermal system was analysed through hydrogeological and microbial community investigations. Mesophilic communities were detected in two cold springs, suggesting a negligible influence of thermal circuits in freshwater sub‐systems which are mainly or only fed by local precipitations. Thermophilic and extremely thermophilic bacteria were detected in two wells, according to higher water temperatures (61 and 85 °C), even if the two communities show significant differences. In one well, thermophilic and extremely thermophilic bacteria are associated with strains belonging to ε‐Proteobacteria isolated in different sulphur‐rich carbonate environments. This association suggests a greater influence on ascending hot fluids that interact with the carbonate basement of volcanic rocks. In the other well, thermophilic and extremely thermophilic bacteria are associated with strains isolated in cold hypersaline environments or in aquatic habitats where terrestrial and marine components are coupled. This association supports the fact that seawater intrusion can affect this part of Ischia, according to results of hydrogeological and geochemical surveys. Differences in groundwater temperature and bacterial communities are probably mainly due to differences in permeability between volcanic rocks and differences in hydrogeologic behaviour between faults in the upper carbonate basement, above the deep magma chamber, that influence relationships between ascending hot fluids and local recharge. This study contributes to discussion of the reliability of the actual behaviour models of the Ischia system, based on the results of geochemical and isotopic investigations, and, in a wider context, it shows that microbial community investigations may be a valuable supplementary tool for analysing hydrothermal system behaviour. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
34.
Adjustments in channel morphology due to land‐use changes and check dam installation in mountain torrents of Calabria (southern Italy) 下载免费PDF全文
Diego Fortugno Carolina Boix‐Fayos Giuseppe Bombino Pietro Denisi Juan Manuel Quiñonero Rubio Vincenzo Tamburino Demetrio Antonio Zema 《地球表面变化过程与地形》2017,42(14):2469-2483
In Mediterranean semi‐arid conditions, the availability of studies monitoring channel adjustments as a response to reforestation and check dams over representative observation periods, could help develop new management strategies. This investigation is an integrated approach assessing the adjustments of channel morphology in a typical torrent of southern Italy after land‐use changes and check dam construction across a period of about 60 years. A statistical analysis of historical rainfall records, an analysis of land‐use changes in the catchment area and a geomorphological mapping of channel adjustments were carried out and combined with field surveys of bed surface grain‐size over a 5‐km reach including 14 check dams. The analysis of the historical rainfall records showed a slight decrease in the amount and erosivity of precipitation. Mapping of land‐use changes highlighted a general increase of vegetal coverage on the slopes adjacent to the monitored reaches. Together with the check dam network installation, this increase could have induced a reduction in water and sediment supply. The different erosional and depositional forms and adjustments showed a general narrowing between consecutive check dams together with local modifications detected upstream (bed aggradation and cross‐section expansion together with low‐flow realignments) and downstream (local incision) of the installed check dams. Changes in the torrent bends were also detected as a response to erosional and depositional processes with different intensities. The study highlighted: the efficiency of check dams against the disrupting power of intense floods by stabilizing the active channel and the influence of reforestation in increasing hillslope protection from erosion and disconnectivity of water and sediment flows towards the active channel. Only slight management interventions (for instance, the conversion of the existing check dams into open structures) are suggested, in order to mobilize the residual sediment avoiding further generalized incision of the active channel and coast line erosion. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
35.
Luigi Tosi Pietro Teatini Laura Carbognin Jane Frankenfield 《Environmental Geology》2007,52(5):889-898
The paper deals with the implementation of a levelling and Global Positioning System (GPS) network to control land subsidence
in the coastal area north of the Venice Lagoon. About 480 km of levelling lines with 527 benchmarks, 45 of which suited for
Differential GPS measurements, were established in 2004. A complete survey of the net was carried out in 2004 soon after its
establishment. The 2004 records have been compared with previous scattered data obtained by the use of levelling surveys,
DGPS and SAR interferometry. The results show a trend in land settlement that increases from the lagoon margin to the north
and jeopardize the Venice coastland. Groundwater withdrawals for domestic, agricultural, and health spas uses, peat oxidation
of reclaimed marshlands for farming, natural consolidation of the Holocene deposits, and tectonics of the pre-Quaternary basement
are the causes of land subsidence in the study area. Since most of the area lies below the mean sea level and on account of
the expected sea level rise due to global change, a detailed monitoring of land displacements in the near future will be of
paramount importance to plan necessary works for coastland protection. 相似文献
36.
Modeling regional initiation of rainfall-induced shallow landslides in the eastern Umbria Region of central Italy 总被引:3,自引:6,他引:3
Diana Salciarini Jonathan W. Godt William Z. Savage Pietro Conversini Rex L. Baum John A. Michael 《Landslides》2006,3(3):181-194
We model the rainfall-induced initiation of shallow landslides over a broad region using a deterministic approach, the Transient Rainfall Infiltration and Grid-based Slope-stability (TRIGRS) model that couples an infinite-slope stability analysis with a one-dimensional analytical solution for transient pore pressure response to rainfall infiltration. This model permits the evaluation of regional shallow landslide susceptibility in a Geographic Information System framework, and we use it to analyze susceptibility to shallow landslides in an area in the eastern Umbria Region of central Italy. As shown on a landslide inventory map produced by the Italian National Research Council, the area has been affected in the past by shallow landslides, many of which have transformed into debris flows. Input data for the TRIGRS model include time-varying rainfall, topographic slope, colluvial thickness, initial water table depth, and material strength and hydraulic properties. Because of a paucity of input data, we focus on parametric analyses to calibrate and test the model and show the effect of variation in material properties and initial water table conditions on the distribution of simulated instability in the study area in response to realistic rainfall. Comparing the results with the shallow landslide inventory map, we find more than 80% agreement between predicted shallow landslide susceptibility and the inventory, despite the paucity of input data. 相似文献
37.
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39.
In this paper, the distribution patterns and abundance of pelagic tunicates in the North Yellow Sea of China during the period 2006-2007 were analyzed. Zooplankton samples were obtained with vertical towing from bottom to surface using a WP2 plankton net(200 μm mesh size; mouth area: 0.25 m2). Five species belonging to two classes were identified: Oikopleura dioica, O. longicauda and Fritillaria borealis belonging to class Appendicularia; Salpa fusiformis and Doliolum denticulatum of class Thaliacea. O. dioica and O. longicauda were the dominant species, occurring in the samples of all four seasons, with different distribution patterns. Their maximum abundance were 1664.7 ind. m-3(spring) and 1031.7 ind. m-3(spring) respectively. Following Oikopleura spp. were D. denticulatum, which was found only in autumn with an average abundance of 149.6 ind. m-3, and S. fusiformis, which was detected all the year long except for autumn with low abundance(max. abundance 289.4 ind. m-3 in summer). Only a very small amount of F. borealis was detected in summer samples, with an average abundance of 2.7 ind. m-3. The relationship between tunicates abundances and the environmental factors was analyzed using the stepwise regression model for each species. The variation of appendicularian abundance showed a significant correlation with the surface water temperature and with the concentration of Chl-a. No relationship was found between tunicates abundance and salinity, likely due to the slight changes in surface salinity of the studied area during the four seasons. Salps abundance and that of doliolids were significantly correlated to bottom water temperature, indicating that these two species(S. fusiformis and D. denticulatum) migrate vertically in the water column. In particular D. denticulatum, known to be a warm water species, showed not only an important correlation with water temperature, but also a spatial distribution connected to the warm currents in the North Yellow Sea. The occurrence of D. denticulatum represents an interesting result never found in past research work. Water temperature, algal distribution and currents were the most relevant environmental factors influencing the tunicate abundance and distribution in the North Yellow Sea. Further research is needed in order to get more information on the ecology of these organisms and to better understand their role in the ecosystem including the oceanic food web. 相似文献
40.
Pietro Carveni Giuliana Mele Santo Benfatto Sebastiano Imposa Maria Salleo Puntillo 《Bulletin of Volcanology》2011,73(9):1155-1162
The row of pyroclastic cones named Mts. Sartorius, outcropping on the NE flank of Etna, formed in 1865 during a lateral eruption
that lasted about 6 months. The event was eye witnessed and described by numerous scientists and reporters. In this work,
we use their observations to reconstruct the eruption chronology and scenario, and carry out a detailed geomorphologic survey
to identify the eruptive features and pyroclastic deposits. The 1865 eruption began on 29 January along a segment of the main
system of fractures oriented ENE–WSW, radial to the central conduit. After 30 January, a secondary system of fractures trending
NNW–SSE was simultaneously active. The six larger Mts. Sartorius cones developed since 3 February along the lower extension
of the radial system. They are markedly asymmetric due to the persistent winds blowing at the time and to the pre-existing
topography formed on underlying deposits, previously unreported, that we have recognized. Now, about 150 years after the eruption,
most of the eruptive vents and fractures are no longer observable in the field, being mostly hidden by products of subsequent
phases of the eruption and by younger epiclastic deposits. 相似文献