Displacement patterns of a landslide affected by human activities: insights from ground-based InSAR monitoring   总被引：2，自引：0，他引：2  

Francesca Bozzano  Ivan Cipriani  Paolo Mazzanti  Alberto Prestininzi 《Natural Hazards》2011,59(3):1377-1396

Landslides interacting with large infrastructures represent a major problem for the economy, society as a whole, and the safety of workers. Continuous monitoring for 23 months using an integrated platform with a ground-based SAR interferometer (GB-InSAR), a weather station, and an automatic camera gave us the opportunity to analyze the response of an unstable slope to the different phases of work. The deformational behavior of both the natural slope and the man-made structures was recorded and interpreted in relation to the working stages and the rainfall conditions during the whole monitoring period. A typical pattern of displacement was identified for shallow landslides, debris produced by the excavation and gabions, metallic walls, and anchored bulkheads. Furthermore, insights into the dynamics and behavior of the slope and the man-made structures that interact with the landslide were obtained. Extreme rainfall is the main trigger of shallow landslides and gabion deformations, while anchored bulkheads are less influenced by rainfalls. Movement of debris that is produced by excavations and temporary metallic barrier deformation are closely related to each other. The herein proposed monitoring platform is very efficient in monitoring unstable slopes that are affected by human activities. Moreover, the recorded patterns of displacement in the slope and the man-made structures can be used as reference data for similar studies and engineering designs.  相似文献   

Time and duration of Variscan high-temperature metamorphic processes in the south European Variscides: constraints from U-Pb chronology and trace element chemistry of zircon   总被引：1，自引：0，他引：1  

Annamaria Fornelli  Antonio Langone  Francesca Micheletti  Giuseppe Piccarreta 《Mineralogy and Petrology》2011,103(1-4):101-122

The lower crust of the Serre massif (Calabria, southern Italy) provides a window into the mid- to lower crust of the south European Variscan orogenic belt. Previously, zircon U-Pb ages were employed to date high-temperature processes affecting this portion of the Variscan crust. The present paper reports new LA-ICP-MS U-Pb data on the zircon of a deformed quartz-monzodiorite dike and of three mafic granulites sampled at the base of the lower crust section. Determination of trace elements on zircon, including rare earth elements (REE), has been also performed. The end of the Variscan exhumation, dated by anatectic zircon from migmatitic metapelites, and the growth-modification of zircon with respect to the growth of Variscan metamorphic garnet have been assumed as ??time markers??. The concordant zircon ages of the metamorphic basic rocks cover a range from 744?±?20 Ma to 231?±?10 Ma with high age density from 357?±?11?Ma to 279?±?10 Ma, a few ages comprised between 418?±?14 Ma and 483?±?12 Ma and between 505?±?11 Ma and 593?±?14 Ma. Zircon from the deformed quartz-monzodiorite dike evidences a minimum age of emplacement of 323?±?5 Ma. Most of the analysed zircon domains dated between 357?±?11 Ma to 279?±?10 Ma from garnet-bearing metabasic rocks show flat patterns of heavy rare earth elements (HREE), as expected in the case of their simultaneous growth with garnet. This allows to consider (1) zircon domains giving Variscan ages as ??metamorphic?? with specific geological significance, and (2) zircon domains with ages ranging from 564?±?17 Ma to 593?±?14 Ma as dating the emplacement of the magmatic protoliths as shown by internal microtextures, fractionated patterns of HREE and Th/U ratios (0.16?C0.19). The Variscan zircon ages (357?C279?Ma) reflect effects of crustal thickening, peak metamorphism and subsequent multistage Variscan decompression documented by the statistically significant clusters of ages around 347?C340?Ma, 323?C318?Ma, 300?C294?Ma and 279?Ma. The U-Pb zircon ages of the metabasic rocks suggest a period of about 60?C70?Ma for granulite facies metamorphism and anatectic conditions. Literature data indicate that the migmatitic metapelites of the upper part of the Serre crust section also underwent a long period, about 40?Ma, of granulite facies metamorphism and anatectic conditions. A diachronism emerges through the time comparison of the Variscan evolution between the upper and the lower portions of the Serre deep crust. The duration of the Variscan processes defined in Calabria is comparable to that of other south European Variscan blocks.  相似文献   

The Bulgheria canyon-fan: a small-scale proximal system in the eastern Tyrrhenian Sea (Italy)     

Francesca Budillon  Alessandro Conforti  Renato Tonielli  Giovanni De Falco  Gabriella Di Martino  Sara Innangi  Ennio Marsella 《Marine Geophysical Researches》2011,32(1-2):83-97

The Bulgheria canyon-fan system in the eastern Tyrrhenian Sea displays well-developed, small-scale, fluvial-like features and has formed alongside the northern slope of the Sapri peri-Tyrrhenian basin. This study reveals, for the first time, the morphology and course of the present-day system as well as the buried elements based on a Digital Terrain Model and high-resolution seismic profiles interpretation. Two adjacent canyons (Infreschi and Luna) originate in the Cilento outer shelf at a short distance from each other and feed an intraslope basin fan through two main sub-parallel channels that run about 12 and 8 km, respectively. Channel and levee development seems to be controlled primarily by the local slope gradient and by Coriolis forces that induce a faster vertical growth of the right-side features, as is often observed in the Northern Hemisphere. Centrifugal forces, on the other hand, have induced episodic flow-stripping at the meander loops and bends, causing local destruction of the main channel levees rather than new levee growth at the outer bends. Overbank deposits are associated with overspill turbidite deposition in the mid fan where a topographic constraint occurs, whereas large-sediment, low-angle wave fields are mainly developed on the outer fan. Buried features and relict morphologies suggest that the Infreschi channel experienced at least two phases of re-incision since the final stages of the middle Pleistocene. Local re-adjustment of outer lobe growth due to channel avulsion and meander abandonment is possibly a consequence of relative base-level fluctuations. The sedimentary record of the mid and outer fan includes outrun mass wasting deposits from extensive failures of the Sapri slope. Indeed, a marked scar is present on the eastern side of the modern outer lobe that indicates the persistency of mass flow passages up to recent times. In addition to the environmental factors that are currently considered to cause canyon formation on the shelf margin, this study proposes the possibility that the head canyon branch close to the mainland was incised by massive and persistent underground freshwater flow from the adjacent aquifer when the sea-level was lower than at present.  相似文献   

Interpreting odours in hermit crabs: A comparative study     

Elena Tricarico  Thomas Breithaupt  Francesca Gherardi 《Estuarine, Coastal and Shelf Science》2011

Odours of different sources can indicate to hermit crabs the availability of empty shells, crucial resources for the life cycle of almost all of them. Here, we compared Clibanarius erythropus and Pagurus bernhardus for the intensity of investigative behaviour exhibited towards an empty, well-fitting shell in the presence of (1) plain seawater as control and seawater conditioned by (2) dead and live snails, (3) dead and live conspecifics, (4) live predators, and (5) food. During 10 min of observation, we recorded latency (the time until the first contact with the shell), and the number and duration of shell investigation bouts. The two species behaved similarly when exposed to the odours of food, live snails, and predators, while a more intense shell investigation was induced by dead snail odour in C. erythropus and by dead or live conspecific odour in P. bernhardus. Further studies should investigate the influence of phylogeny and ecology on this interspecific difference.  相似文献   

The effect of star formation on the evolution of Blue Compact Dwarf galaxies     

Simone Recchi  Francesca Matteucci  Annibale D'Ercole  Monica Tosi 《Astrophysics and Space Science》2003,284(2):623-626

We study the effect of different star formation regimes on the dynamical and chemical evolution of Blue Compact Dwarf galaxies. To do that, we adopt a 2-D hydrocode coupled with detailed chemical yields originating from SNeII, SNeIa and from intermediate-mass stars. We apply this kind of simulation to a model of galaxy resembling IZw18. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

UVES Abundances of Stars in Nearby Dwarf Spheroidal Galaxies     

Eline Tolstoy  Kim Venn  Matt Shetrone  Francesca Primas  Vanessa Hill  Andreas Kaufer  Thomas Szeifert 《Astrophysics and Space Science》2002,281(1-2):217-218

It is a truth universally acknowledged, that a galaxy in possession of a good quantity of gas must want to form stars. It is the details of how and why that baffle us all. The simplest theories either would have this process a carefully self-regulated affair, or one that goes completely out of control and is capable of wrecking the galaxy which hosts it. Of course the majority of galaxies seem to amble along somewhere between these two extremes, and the mean properties tend to favour a quiescent self-regulated evolutionary scenario. But there area variety of observations which require us to invoke transitory ‘bursts’ of star-formation at one time or another in most galaxy types. Several nearby dwarf spheroidal galaxies have clearly determined star-formation histories with apparent periods of zero star formation followed by periods of fairly active star formation. If we are able to understand what separated these bursts we would understand several important phenomena in galaxy evolution. Were these galaxies able to clear out their gas reservoir in a burst of star formation? How did this gas return? or did it? Have these galaxies receieved gas from the IGM instead? Could stars from these types of galaxy contribute significantly to the halo population in our Galaxy? To answer these questions we need to combine accurate stellar photometry and Colour-Magnitude Diagram interpretation with detailed metal abundances to combine a star-formation rate versus time with a range of element abundances with time. Different elements trace different evolutionary process (e.g., relative contributions of type I and II supernovae). We often aren't even sure of the abundance spread in these galaxies. We have collected detailed high resolution UVES spectra of four nearby dwarf spheroidal galaxies (Sculptor, Fornax, Leo I &; Carina) to begin to answer these questions. This is a precursor study to a more complete study with FLAMES. We presented at this meeting the initial results for the Sculptor and Fornax dwarf spheroidal galaxies which have been previously had single element (low resolution) calcium abundance studies (Tolstoy et al., 2001). See Figures 1 and 2.  相似文献   

Observations of Jet Diameter, Density and Dynamics     

Francesca Bacciotti  Thomas P. Ray  Jochen Eislöffel  Jens Woitas  Josef Solf  Reinhard Mundt  Christopher J. Davis 《Astrophysics and Space Science》2003,287(1-4):3-13

Collimated jets are believed to be an essential ingredient of the star formation process, and we are now able for the first time to test observationally the theories for their formation and propagation. The major advances achieved in recent years are reviewed, regarding the observed morphology, kinematics and excitation properties of jets, from the parsec-scale `giant outflows' down to the `microjets' from T Tauri stars. High angular resolution images and spectra have provided valuable estimates of jet diameter, space velocity, temperature, ionization fraction, electron and total density, both along and across the flow. We can thus calculate key physical quantites, as the shock excitation parameters, or the mass and momentum fluxes in the flow. The results obtained appear to validate the popular magneto-centrifugal models for jet launching, although some important issues are still under debate, as to the cause of knotty structures, observed wind thermal properties, and the dynamical relationship between jets and molecular outflows. Among the most interesting recent findings, we mention the observed indications for jet rotation, with inferred toroidal velocities consistent with the prescribed angular momentum balance between infall and outflow.  相似文献   

The evolution of cosmic star formation, metals and gas     

Francesco Calura  Francesca Matteucci 《Astrophysics and Space Science》2003,284(2):429-432

We reconstruct the history of the cosmic star formation as well as the cosmic production of metals in the universe by means of detailed chemical evolution models for galaxies of different morphological types. We consider a picture of coeval, non-interacting evolving galaxies where ellipticals experience intense and rapid starbursts within the first Gyr after their formation, and spirals and irregulars continue to form stars at lower rates up to the present time. We show that spirals are the main contributors to the decline of the luminosity density in all bands between z=1 and z=0. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

K dwarfs and the chemical evolution of the solar cylinder     

Eira Kotoneva  Chris Flynn  _&#; †  Cristina Chiappini  Francesca Matteucci 《Monthly notices of the Royal Astronomical Society》2002,336(3):879-891

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The Best Observables from the Point of View of a Model Maker     

Francesca Matteucci 《Astrophysics and Space Science》2001,277(1):17-26

We select and discuss the best observables to be used to constrain models of galactic chemical evolution. To this purpose, we discuss the observables in our Galaxy, which is the best studied system, as well as in external galaxies.  相似文献