Erosion and morphology of a debris flow caused by a glacial lake outburst flood,Western Norway   总被引：5，自引：2，他引：3  

Hedda Breien  Fabio V. De Blasio  Anders Elverhøi  Kaare Høeg 《Landslides》2008,5(3):271-280

This article documents a 240,000-m³ debris flow resulting from a glacial lake outburst flood in Fjærland, Western Norway, May 8, 2004. The event started when a glacial lake breached a moraine ridge. The ensuing debris flow was able to erode material along its path, increasing in volume from about 25,000 to 240,000 m³ before depositing about 3 km from its starting point. Field investigations, pre- and post-flow aerial photographs as well as airborne laser scanning (LIDAR) were used to describe and investigate the flow. The most striking and unusual feature of this case study is the very pronounced erosion and bulking. We have made a detailed study of this aspect. Erosion and entrainment is quantified and the final volume of the debris flow is determined. We also present geometrical and sedimentological features of the final deposit. Based on the Fjærland data, we suggest that a self-sustaining mechanism might partly explain the extreme growth of debris flows traversing soft terrain.  相似文献   

Spatial analysis of clay content in soils using neurocomputing and pedological support: a case study of Valle Telesina (South Italy)     

Giuliano Langella  Angelo Basile  Antonello Bonfante  Florindo Antonio Mileti  Fabio Terribile 《Environmental Earth Sciences》2016,75(20):1357

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Characteristics of the strong ground motions from the 6 April 2009 L’Aquila earthquake,Italy     

Aybige Akinci  Luca Malagnini  Fabio Sabetta 《Soil Dynamics and Earthquake Engineering》2010,30(5):320-335

An M_w 6.25 earthquake occurred on April 6, 2009 at 03:33 a.m. local time, in the Abruzzo region (Central Italy), close to the city of L’Aquila. The earthquake ruptured a North-West (NW)–South-East (SE) oriented normal fault dipping toward the South-West (SW), with the city of L’Aquila lying a few kilometers away on the hanging wall.The main shock has been recorded by fifty-eight accelerometric stations: the highest number of digital recordings ever obtained in Italy for a single earthquake, one of the best-recorded earthquakes with a normal fault mechanism. Very high values of peak ground acceleration (0.3–0.65 g) were observed close to the center of L’Aquila (6 stations at zero JB distance from the fault). The earthquake caused severe loss of lives (299 victims and 1500 injured) and damage (about 18000 unusable buildings) in the epicentral area.In this study we analyze the ground motion characteristics of both the main shock in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo-acceleration response spectra (5% of damping ratio). In particular, we compare the pseudo-acceleration response spectra for horizontal directions with the EC8 design spectrum and the new Italian building code (NTC08). In order to understand the characteristics of the ground motions induced by L’Aquila earthquake, we also study the source-related effects and site response of the strong motion stations that recorded the seismic sequence. A novel method is used for the analysis of inter-station and site-specific H/V spectral ratios for the main event and for 12 aftershocks.  相似文献   

An innovative application of the Kinect in Earth sciences: quantifying deformation in analogue modelling of volcanoes     

Riccardo Tortini  Fabio L. Bonali  Claudia Corazzato  Simon A. Carn  Alessandro Tibaldi 《地学学报》2014,26(4):273-281

Measuring surface deformation is critical in analogue modelling of Earth science phenomena. Here, we present a novel application of the Microsoft Kinect sensor to measure vertical deformation in a scaled analogue model of Nisyros volcano (Greece), simulating two magmatic sources and related surface deformation. The Kinect permits capture of real time, 640 × 480 pixel, true‐colour images (RGB) and a grid of distances to the modelled surface with a horizontal and vertical resolution of ±1 mm. Using recorded distances permits quantification of vertical deformation in terms of maximum and average down‐ and uplift during deflation and inflation phases respectively, which is of crucial importance for defining the kinematics of faults formed during the modelling, determined from interpretation of the RGB images. Although other techniques have demonstrated similar or higher accuracy, our study demonstrates the cost‐effectiveness of the Kinect in analogue modelling of volcanoes.  相似文献   

Preliminary Discrete Particle Model in a Computer Simulation of Cohesive Debris Flows     

Fabio V. De Blasio 《Geotechnical and Geological Engineering》2012,30(1):269-276

The paper presents a numerical method to simulate the dynamics of a cohesive debris flow. The model is based on a molecular dynamics algorithm where the equation of motion is calculated for an ensemble of interacting particles. In addition to the hard-core repulsion and to the other forces commonly introduced to simulate granular media, in this work an attractive force between particles is added as a model for cohesion. The model is computationally straightforward and devoid of a series of cumbersome problems affecting fluid mechanical codes. Preliminary simulations presented here look promising, and indicate directions of study for a better comparison and test against field data.  相似文献   

Landslides in Valles Marineris (Mars): A possible role of basal lubrication by sub-surface ice   总被引：1，自引：0，他引：1  

Fabio Vittorio De Blasio 《Planetary and Space Science》2011,59(13):1384-1392

There is much interest on the occurrence of water and ice in the past history of Mars. Because landslides on Mars are much better conserved than their terrestrial counterparts, a physical examination and morphological analysis can reveal significant details on the depositional environment at the instant of failure. A study of the landslides in Valles Marineris based on their physical aspect is presented and the velocity of the landslides is calculated with a stretching block model. The results show that the landslides were subject to strong basal lubrication that made them travel at high speed and to long distances. We use physical analysis to explore the four alternative possibilities that the natural lubricant of the landslides in Valles Marineris was either ice, deep water, a shallow carpet of water, or evaporites. Examination of the furrows present on the surface of the landslide deposits shows that either sub-surface ice or evaporites were likely present on the floor of Valles Marineris during the mass failures.  相似文献   

Variability of the health effects of crystalline silica: Fe speciation in industrial quartz reagents and suspended dusts—insights from XAS spectroscopy     

Francesco Di Benedetto  Francesco D’Acapito  Fabio Capacci  Gabriele Fornaciai  Massimo Innocenti  Giordano Montegrossi  Werner Oberhauser  Luca A. Pardi  Maurizio Romanelli 《Physics and Chemistry of Minerals》2014,41(3):215-225

We investigated the speciation of Fe in bulk and in suspended respirable quartz dusts coming from ceramic and iron-casting industrial processes via X-ray absorption spectroscopy, with the aim of contributing to a better understanding of the variability of crystalline silica toxicity. Four different bulk industrial quartz powders, nominally pure quartz samples with Fe contents below 200 ppm, and three respirable dusts filters were selected. Fe speciation was determined in all samples through a coupled study of the X-ray absorption near-edge structure and extended X-ray absorption fine structure regions, operating at the Fe–K edge. Fe speciation revealed common features at the beginning of the different production processes, whereas significant differences were observed on both respirable dusts and bulk dusts exiting from the production process. Namely, a common pollution of the raw quartz dusts by elemental Fe was evidenced and attributed to residuals of the industrial production of quartz materials. Moreover, the respirable samples indicated that reactivity occurs after the suspension of the powders in air. The gravitational selection during the particle suspension consistently allowed us to clearly discriminate between suspended and bulk dusts. On the basis of the obtained results, we provide an apparent spectroscopic discrimination between the raw materials used in the considered industrial processes, and those that are effectively inhaled by workers. In particular, an amorphous Fe^III oxide, with an unsaturated coordination sphere, can be related to silica reactivity (and health consequences).  相似文献   

Wind-induced salt-wedge intrusion in the Tiber river mouth (Rome–Central Italy)     

Fabio Manca  Giuseppe Capelli  Francesco La Vigna  Roberto Mazza  Annalisa Pascarella 《Environmental Earth Sciences》2014,72(4):1083-1095

The wind effect on river water quality was illustrated by means of thermohaline measurements carried out in the Tiber River in May 2012. The survey was carried out using a boat, in stations located in the two Tiber branches: Fiumara Grande and Traiano Canal. Thermohaline variables (salinity and temperature) were used to describe the water-type patterns and to define the salt-wedge position. Although the river flow rate was rather high, saltwater intrusion happened. Wind data suggested that the more probable cause of salt-wedge intrusion was the wind action. Especially wind speeds higher than 4 m/s are able to dominate the sea current at surface layers, determining an increase in the sea level. Therefore, westerly winds determined a seawater inflow in the river mouths.  相似文献   

A stratigraphic and geophysical approach to studying the deep-circulating groundwater and thermal springs, and their recharge areas, in Cimini Mountains–Viterbo area, central Italy     

Ugo Chiocchini  Fabio Castaldi  Maurizio Barbieri  Valeria Eulilli 《Hydrogeology Journal》2010,18(6):1319-1341

The stratigraphic and structural setting of the Cimini Mountains and Viterbo area of Italy has been reconstructed. The architecture of the tectonic edifice, below the Pleistocene Cimino and Vicano volcanic districts cover, is characterized by the Mesozoic–Cenozoic Tuscan Nappe and the similar Umbria-Marche Succession; both are capped by the overthrusted Ligurian Late Cretaceous–Eocene Tolfa Flysch. A shallow unconfined volcanic aquifer is separated, by a thick aquiclude, from the deep confined carbonate aquifer consisting of the Tuscan Nappe and the Umbria-Marche Succession. The volcanic aquifer hosts cold waters, whilst the carbonate aquifer hosts hot sulphate–alkaline earth waters that emerge in the thermal area of Viterbo with a temperature of 30–60°C. The recharge area of cold waters is located in the Cimini Mountains. Thermal waters of the Viterbo hot springs are derived from a circuit of waters that emerge along the River Nera near Narni (about 34 km ENE of Viterbo), with a high salinity, a temperature of 16–18°C, a sulphate–alkaline earth composition, and a discharge of 13 m³/sec, whose recharge area is located in the central pre-Apennines reliefs.  相似文献   

A multidisciplinary approach to reveal the Sicily Climate and Environment over the last 20 000 years     

Alessandro Incarbona  Giuseppe Zarcone  Mauro Agate  Sergio Bonomo  Enrico Di Stefano  Federico Masini  Fabio Russo  Luca Sineo 《Central European Journal of Geosciences》2010,2(2):71-82

We present a thorough review of the knowledge on the climate and environment in Sicily over the last 20 000 years, taking into account results of several studies carried using terrestrial and marine records. We obtain a coherent framework of the most important changes succeeded in the island, even if some points need further investigation. All the reconstructions of surface temperatures of the seas and the air surrounding Sicily point out severe climatic conditions during the last glacial period. The steppe- and semisteppe-like vegetation pattern testifies, together with additional evidence from geochemical data of lacustrine evidence, markedly arid conditions. Fi-nally, significant episodes of sea level drop connected Sicily to the Italian Peninsula and favoured the dispersion of faunal elements from southern Italy. The transition between the last glacial and the Holocene was not characterized by a gradual warming but was punctuated by two abrupt suborbital climatic fluctuations: Bølling-Allerød (warm) and Younger Dryas (cold), as recognized in the sediments recovered close to the northern and southern coast of Sicily. A denser arboreal cover is possibly indicated by the occurrence of dormouse and Arvicola remains. Finally the sensitivity of Sicily to climate perturbations is demonstrated by the occurrence of repeated subtle climatic anomalies during the Holocene, including the Little Ice Age, also known from historical chronicles. Forests, woods and Mediterranean maquis developed in the early-middle Holocene. Thereafter was a general decline of arboreal vegetation, following a general aridification trend that seems to be a common feature in southern Europe and North Africa. Science Greek colonization (7^th century before Christ), the landscape was intensively modelled for agriculture and breeding, leading to a significant loss of vegetation cover.  相似文献