256 research outputs found
Considerations on geomorphological maps for territorial planning in the Modena Apennines (Northern Italy)
This contribution shows, through some examples, that the current instability processes sometimes do not completely correspond (concerning presence, location, state of activity and/or extent) with those mapped by PTCP Hydrogeological Hazard Maps, which is the document used by the Province Administration for its territorial planning. <br><br> The differences highlighted are due to different causes. One of them is the fact that the PTCP Hydrogeological Hazard Maps are practically derived from the Regional Geological maps in which superficial deposits have secondary importance, while bedrock and structural-tectonic aspects are given the highest relevance. Another cause is represented by the very active and intense geomorphological dynamics of the Apennines which may produce or reactivate instability conditions. <br><br> An important aspect to underline is that the PTCP Hydrogeological Hazard Maps identify areas with planning constraints, which have effects at a municipal scale; it does so by starting from a cartographical basis whose primary aim is not the definition of instability processes and whose updating is not homogeneous. <br><br> Taking into account this aspect, the PTCP Hydrogeological Hazard Maps should be updated not only on the base of traditional geological mapping, but also following the criteria of detailed geomorphological mapping which can precisely define the genesis, dynamics and morphometry of instability phenomena. <br><br> An important consideration, in relation to territorial planning, is that the PTCP Hydrogeological Hazard Maps should be used just as a "base document", which requires more necessary detailed deepening at the municipal scale, accomplished through accurate geomorphological mapping, at least for the areas that are going to be urbanized. <br><br> The geomorphological mapping should also update those elements of the landscape which could have changed from the official topographic base map. <br><br> Detailed geomorphological mapping, possibly undertaken with the methodology proposed in this paper, could be given in charge also to professional geologists in accordance with standard procedures set in collaboration with the Provincial Administration
The survey and mapping of sand-boil landforms related to the Emilia 2012 earthquakes: preliminary results.
Sand boils, which are also known as sand blows or sand volcanoes, are among the most common superficial effects induced by high-magnitude earthquakes. These generally occur in or close to alluvial plains when a strong earthquake (M >5) strikes on a lens of saturated and unconsolidated sand deposits that are constrained between silt-clay layers, where the sediments are converted into a fluid suspension. The liquefaction phenomena requires the presence of saturated and uncompacted sand, and a groundwater table near the ground surface. This geological\u2013geomorphological setting is common and widespread for the Po Plain (Italy). The Po Plain (ca. 46,000 km2) represents 15% of the Italian territory. It hosts a population of about 20 million people (mean density of 450 people/km2) and many infrastructures. Thus, the Po Plain is an area of high vulnerability when considering the liquefaction potential in the case of a strong earthquake. Despite the potential, such phenomena are rarely observed in northern Italy, because strong earthquakes are not frequent in this region; e.g., historical data report soil liquefaction near Ferrara in 1570 (M 5.3) and in Argenta 1624 (M 5.5). In the Emilia quakes of May 20 and 29, 2012, the most widespread coseismic effects were soil liquefaction and ground cracks, which occurred over wide areas in the Provinces of Modena, Ferrara, Bologna, Reggio Emilia and Mantov
The survey and mapping of sand-boil landforms related to the Emilia 2012 earthquakes: preliminary results.
Sand boils, which are also known as sand blows or sand volcanoes, are among the most common superficial effects induced by high-magnitude earthquakes. These generally occur in or close to alluvial plains when a strong earthquake (M >5) strikes on a lens of saturated and unconsolidated sand deposits that are constrained between silt-clay layers, where the sediments are converted into a fluid suspension. The liquefaction phenomena requires the presence of saturated and uncompacted sand, and a groundwater table near the ground surface. This geological–geomorphological setting is common and widespread for the Po Plain (Italy). The Po Plain (ca. 46,000 km2) represents 15% of the Italian territory. It hosts a population of about 20 million people (mean density of 450 people/km2) and many infrastructures. Thus, the Po Plain is an area of high vulnerability when considering the liquefaction potential in the case of a strong earthquake. Despite the potential, such phenomena are rarely observed in northern Italy, because strong earthquakes are not frequent in this region; e.g., historical data report soil liquefaction near Ferrara in 1570 (M 5.3) and in Argenta 1624 (M 5.5). In the Emilia quakes of May 20 and 29, 2012, the most widespread coseismic effects were soil liquefaction and ground cracks, which occurred over wide areas in the Provinces of Modena, Ferrara, Bologna, Reggio Emilia and Mantov
Spatial-distribution of recombination centers in gaaste - effects of the doping level
The distribution in liquid-encapsulated-Czochralski (LEC) GaAs:Te wafers of point and complex defects has been investigated together with their influence on the minority-carrier diffusion length L. Three wafers with different Te-doping concentration (2.2 X 10(17), 4.5 X 10(17), and 1.5 X 10(18) cm-3) have been studied by means of the electron-beam-induced-current (EBIC) mode of scanning electron microscopy and of the surface photovoltage (SPV) method. The morphology and electrical activity of the defects observed across each wafer have been correlated to the formation and distribution of deep electronic levels, which are significantly affected by the tellurium concentration. The diffusion length has been found to be mainly controlled by deep levels associated with dislocations. EBIC localized measurements of L and of the net ionized free-carrier concentration provide evidence for the influence of Te concentration on impurity segregation at complex defects
Soil functionality assessment in degraded plots of vineyards
Land transformation to adapt fields to mechanization in perennial crop farming is a common practice which includes land levelling, deep ploughing, stone-breakage and clearing, application of fertilizers and amendments. Manipulation of the natural soil profile along its entire depth can severely disturb the naturally existing chemical physical,biological and hydrological equilibrium (Costantini and Barbetti, 2008; Costantini et al., 2013). The most common effects of the land transformation are mixing of soil horizons and soil truncation, which result in reduction of soil depth and available water, organic matter depletion, enrichment of calcium carbonate content in the topsoil,imbalance of some element ratio, and decline in the activity and diversity of soil biological communities involved in nutrient cycles. A decline in the capacity of soil to accommodate the soil-dwelling organisms causes a strong impact on several ecosystem services, in particular, the growth of the vine, the quality and quantity of the grapes,the production costs and the risk of erosion.
These negative effects of a pre-planting mismanagement can occur simultaneously and interact to decrease soil fertility and grapevine performance (Lanyon et al., 2004; Tagliavini and Rombolà, 2001; Martínez-Casasnovas and Ramos, 2009).Since soil spatial variability is usually high, soil manipulations frequently result into reduced
soil functionality and decline of soil ecosystem services in defined plots of the vineyards. Sometimes soil degradation in these areas is very high and compromises not
only vine performance and crop yield, but also disease resistance of plants to diseases and their survival. The impact of improper soil manipulations in vineyards may be of
particular concern, because vineyards are frequently located on marginal hillsides, which are sensitive to soil erosion and characterized by shallow soil depth (Ramos, 2006). This paper wants to show the assessment of soil functionality in degraded areas within two farms in Tuscany. This work reports the results of the first activities in Italian sites of the ReSolVe Core-organic+ project, aimed at restoring optimal Soil functionality in
degraded areas within organic European vineyards
The survey and mapping of sand-boil landformsrelated to the Emilia 2012 earthquakes: preliminary results
In this report, we present preliminary results using methods to map the detailed micro-morphology of some representative liquefaction features that normally disappear for the aforementioned reasons, or that are recorded only in qualitative terms.
Field surveys and activities were conducted a few days
after the May 20 and 29, 2012, mainshocks (M 5.9, M 5.8, respectively).
The surveys were carried out using global position
system (GPS) and reflex digital cameras. GPS acquisition
(tracklog) was used to record the topographic positions of the
features and to automatically geolocate/geotag the numerous
digital photos acquired. The field data, geomorphological features,
and sand-boil location were loaded into a geodatabase
and mapped using geographic information systems (GIS).
Photogrammetric surveys were carried out on several
sand boils using digital reflex cameras with calibrated 20-mm
fixed lenses. To build high resolution digital elevation models
(DEMs), images were taken from multiple angles to cover the
entire areas of the features of interest
VLBI Observations of a Complete Sample of Radio Galaxies. VI. The Two FR-I Radio Galaxies B2 0836+29 and 3C465
We present 5 GHz global VLBI observations of the two Fanaroff Riley Type I
radio galaxies B2 0836+29 and 3C465 (2335+26). For 3C465 we present also 1.7
GHz and 8.4 GHz global VLBI data. In addition VLA observations were used to
obtain arsecond resolution continuum and polarization maps at 5 GHz. Both
sources are very asymmetric on the parsec-scale, with a core and a one-sided
jet, aligned with the main arcsecond scale jet. We place a limit on the
milliarcsecond jet to counterjet brightness ratio B/B \gtsim
20 and \gtsim 30 for B2 0836+29 and 3C465 respectively. For 3C465 the strong
asymmetry holds to the kiloparsec scale. The brightness asymmetry and the ratio
between the core radio power and total radio power allow us to constrain the
jet velocity close to the core and the orientation of the radio structure with
respect to the line of sight. The results suggest that the plasma speed is
relativistic on the parsec scale for both sources, i.e. v \gtsim 0.75c
for B2 0836+29 and v \gtsim 0.6c for 3C465. While v decreases
from the parsec to the kiloparsec scale in B2 0836+29, in 3C465 the very high
v holds all the way to the kiloparsec-scale {\t bright spot}. Our
results are in agreement with the unification scheme suggestion that FR-I radio
galaxies are the unbeamed poulation of BL-Lac objects. Furthermore, they
reinforce the idea that the central engine in FR-I and FR-II radio galaxies
must be qualitatively similar. The different radio morphology could then be due
either to an intrinsically different nuclear power, which affects the torus
geometry or to different conditions in the region beyond the parsec scale,
where a significant deceleration in the FR-I jets occurs.Comment: 28 pages, 4 tables, 8 figures all available under request from
[email protected]
3D Engineering Geological Modeling to Investigate a Liquefaction Site: An Example in Alluvial Holocene Sediments in the Po Plain, Italy
Liquefaction-induced surface manifestations are the result of a complex geological–geotechnical phenomenon, driven by several controlling factors. We propose a multidisciplinary methodological approach, involving engineering geologists, geomorphologists, sedimentologists, and geotechnical engineers, to build a 3D engineering geological model for liquefaction assessment studies. The study area is Cavezzo (Po Plain, Italy), which is a municipality hit by superficial liquefaction manifestations during the Emilia seismic crisis of May–June 2012. The site is characterized by a Holocene alluvial sequence of the floodplain, fluvial channel, and crevasse splay deposits prone to liquefaction. The integration of different geotechnical investigations, such as boreholes, CPTm, CPTu, and laboratory tests, allowed us to recognize potentially liquefiable lithological units, crucial for hazard assessment studies. The resulting 3D engineering geological model reveals a strict correlation of co-seismic surface manifestations with buried silty sands and sandy silts within the shallow 10 m in fluvial channel setting, which is capped and laterally confined by clayey and silty deposits
- …
