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101.
102.
Francesco?PerriEmail author Salvatore?Critelli Giovanni?Mongelli Robert?L.?Cullers 《International Journal of Earth Sciences》2011,100(7):1569-1587
The continental redbeds from the Internal Domains of the central-western Mediterranean Chains have an important role in the
palaeogeographic and palaeotectonic reconstructions of the Alpine circum-Mediterranean orogen evolution since these redbeds
mark the Triassic-Jurassic rift-valley stage of Tethyan rifting. The composition and the sedimentary evolution of the Middle
Triassic to Lowermost Jurassic continental redbeds of the San Marco d’Alunzio Unit (Peloritani Mountains, Southern Italy),
based on mineralogical and chemical analyses, suggests that the studied mudrock sediments share common features with continental
redbeds that constitute the Internal Domains of the Alpine Mediterranean Chains. Phyllosilicates are the main components in
the mudrocks. The 10 Å-minerals (illite and micas), the I–S mixed layers, and kaolinite are the most abundant phyllosilicates.
The amount of illitic layers in I–S mixed layers coupled with the illite crystallinity values (IC) are typical of high degree
of diagenesis, corresponding to a lithostatic/tectonic loading of about 4–5 km. The mineralogical assemblage coupled with
the A-CN-K plot suggest post-depositional K-enrichments. Palaeoweathering proxies (PIA and CIW) record intense weathering
at the source area. Further, the studied sediments are affected by reworking and recycling processes and, as consequence,
it is likely these proxies monitor cumulative effect of weathering. The climate in the early Jurassic favoured recycling and
weathering occurred under hot, episodically humid climate with a prolonged dry season. The source-area is the low-grade Paleozoic
metasedimentary basement. Mafic supply is minor but not negligible as suggested by provenance proxies. 相似文献
103.
F. Bozzano L. Lenti Salvatore Martino A. Paciello G. Scarascia Mugnozza 《International Journal of Earth Sciences》2011,100(4):861-879
The basin-like setting of stiff bedrock combined with pre-existing landslide masses can contribute to seismic amplifications
in a wide frequency range (0–10 Hz) and induce a self-excitation process responsible for earthquake-triggered landsliding.
Here, the self-excitation process is proposed to justify the far-field seismic trigger of the Cerda landslide (Sicily, Italy)
which was reactivated by the 6th September 2002 Palermo earthquake (M
s = 5.4), about 50 km far from the epicentre. The landslide caused damage to farm houses, roads and aqueducts, close to the
village of Cerda, and involved about 40 × 106 m3 of clay shales; the first ground cracks due to the landslide movement formed about 30 min after the main shock. A stress–strain
dynamic numerical modelling, performed by FDM code FLAC 5.0, supports the notion that the combination of local geological
setting and earthquake frequency content played a fundamental role in the landslide reactivation. Since accelerometric records
of the triggering event are not available, dynamic equivalent inputs have been used for the numerical modelling. These inputs
can be regarded as representative for the local ground shaking, having a PGA value up to 0.2 m/s2, which is the maximum expected in 475 years, according to the Italian seismic hazard maps. A 2D numerical modelling of the
seismic wave propagation in the Cerda landslide area was also performed; it pointed out amplification effects due to both
the structural setting of the stiff bedrock (at about 1 Hz) and the pre-existing landslide mass (in the range 3–6 Hz). The
frequency peaks of the resulting amplification functions (A(f)) fit well the H/V spectral ratios from ambient noise and the H/H spectral ratios to a reference station from earthquake records, obtained by in situ velocimetric measurements. Moreover,
the Fourier spectra of earthquake accelerometric records, whose source and magnitude are consistent with the triggering event,
show a main peak at about 1 Hz. This frequency value well fits the one amplified by the geological setting of the bedrock
in correspondence with the landslide area, which is constituted of marly limestones and characterised by a basin-like geometry. 相似文献
104.
105.
Restoration of the eutrophic Orbetello lagoon (Tyrrhenian Sea, Italy): water quality management 总被引:2,自引:0,他引:2
The Orbetello lagoon (Tyrrhenian coast, Italy) receives treated urban and land based fishfarms wastewater. The development of severe eutrophication imposed the three main activity adoption focuses on (1) macroalgae harvesting; (2) pumping of water from the sea; (3) confining wastewater to phytotreatment ponds. The responses to these interventions were rapid and macroalgal reduction growth and seagrass return were recorded. Since 1999, a new macroalgal development was recorded. The aim of this research was to discover whether the recent macroalgal growth can be attributed to the continuing wastewater influx from the remaining persistent anthropic sources (PAS) or from the sediment nutrient release. A monitoring programme was carried out between August 1999 and July 2000 in order to measure dissolved inorganic nitrogen and phosphorus in the wastewaters entering into the lagoon and in central lagoon areas, seaweed and seagrass distribution and lagoon N, P annual budgets. The results showed higher N and P values close to PAS. The distribution of the macroalgal species confirms that the available P comes almost entirely from these remaining PAS. In conclusion, the environmental measures adopted produced a significant reduction in algal biomass development in the lagoon; the macroalgal harvesting activities produced a sediment disturbance with following oxidize conditions, which make P unavailable in the lagoon water, excepting close the PAS. 相似文献
106.
Salvatore Alparone Graziella Barberi Alessandro Bonforte Vincenza Maiolino Andrea Ursino 《Bulletin of Volcanology》2011,73(7):869-885
We carried out a study of the seismicity and ground deformation occurring on Mt. Etna volcano after the end of the 2002–2003
eruption and before the onset of the 2004–2005 eruption. Data were recorded by the permanent local seismic network run by
Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Catania and by geodetic surveys carried out in July 2003 and July 2004 on the GPS network. Most earthquakes were grouped in two main
clusters located in the northeastern and southeastern sectors of the volcano. The areal distribution of seismic energy associated
with the recorded earthquakes allowed us to highlight the main seismogenic areas of Mt. Etna. In order to better understand
the kinematic processes of the volcano, 3D seismic locations were used to compute fault plane solutions, and a selected dataset
was inverted to determine stress and strain tensors. The focal mechanisms in the northeastern sector show clear left-lateral
kinematics along an E-W fault plane, consistent with events occurring along the Pernicana Fault system. The fault plane solutions
in the southeastern sector show mainly right-lateral kinematics along a NNE and ENE fault plane and left lateral-kinematics
along NW fault planes that together suggest roughly E-W oriented compression. Surface ground deformation affecting Mt. Etna
measured by GPS surveys highlighted a marked inflation during the same period and exceptionally strong seawards motion of
its eastern flank. The 2D geodetic strain tensor distribution was calculated and the results show mainly ENE-WSW extension
coupled with WNW-ESE contraction, indicating right-lateral shear along a NW-SE oriented fault plane. The different deformation
of the eastern sector of the volcano, as measured by seismicity and ground deformation, must be interpreted by considering
the different depths of the two signals. Seismic activity in the southeastern sector of volcano is located between 3 and 8 km b.s.l.
and can be associated with a very strong additional E-W compression induced by a pressurizing source just westwards and at
the same depth, located by inverting GPS data. Ground deformation, in contrast, is mainly affected by the shallower dynamics
of the fast moving eastern flank which produces a shallower opposing E-W extension. The entire dataset shows that two different
processes affect the eastern flank at the same time but at different depths; the boundary is clearly located at a depth of
3 km b.s.l. and could represent the décollement surface for the mobile flank. 相似文献
107.
A framework is proposed to characterize and forecast the displacement trends of slow-moving landslides, defined as the reactivation stage of phenomena in rocks or fine-grained soils, with movements localized along one or several existing shear surfaces. The framework is developed based on a thorough analysis of the scientific literature and with reference to significant reported case studies for which a consistent dataset of continuous displacement measurements is available. Three distinct trends of movement are defined to characterize the kinematic behavior of the active stages of slow-moving landslides in a velocity-time plot: a linear trend-type I, which is appropriate for stationary phenomena; a convex shaped trend-type II, which is associated with rapid increases in pore water pressure due to rainfall, followed by a slow decrease in the groundwater level with time; and a concave shaped trend-type III, which denotes a non-stationary process related to the presence of new boundary conditions such as those associated with the development of a newly formed local slip surface that connects with the main existing slip surface. Within the proposed framework, a model is developed to forecast future displacements for active stages of trend-type II based on displacement measurements at the beginning of the stage. The proposed model is validated by application to two case studies. 相似文献
108.
Louise Crochemore Charles Perrin Vazken Andréassian Uwe Ehret Simon P. Seibert Salvatore Grimaldi 《水文科学杂志》2013,58(3):402-423
AbstractThis paper investigates the relationship between expert judgement and numerical criteria when evaluating hydrological model performance by comparing simulated and observed hydrographs. Using a web-based survey, we collected the visual evaluations of 150 experts on a set of high- and low-flow hydrographs. We then compared these answers with results from 60 numerical criteria. Agreement between experts was found to be more frequent in absolute terms (when rating models) than in relative terms (when comparing models), and better for high flows than for low flows. When comparing the set of 150 expert judgements with numerical criteria, we found that most expert judgements were loosely correlated with a numerical criterion, and that the criterion that best reflects expert judgement varies from expert to expert. Overall, we identified two groups of 10 criteria yielding an equivalent match with the expertise of the 150 participants in low and high flows, respectively. A single criterion common to both groups (the Hydrograph Matching Algorithm with mean absolute error) may represent a good indicator for the overall evaluation of models based on hydrographs. We conclude that none of the numerical criteria examined here can fully replace expert judgement when rating hydrographs, and that both relative and absolute evaluations should be based on the judgement of multiple experts.
Editor D. Koutsoyiannis 相似文献
109.
110.
Andrea Cannata Iole Serena Diliberto Salvatore Alparone Salvatore Gambino Stefano Gresta Marcello Liotta Paolo Madonia Vincenzo Milluzzo Marco Aliotta Placido Montalto 《Pure and Applied Geophysics》2012,169(1-2):167-182
Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 2004–2007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took place during four “anomalous” periods (November 2004–March 2005; October 2005–February 2006; August–October 2006; July–December 2007) at the same time as an increasing number of volcano-seismic events. In particular, the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440°C and from 20 to 90°C, respectively. The maximum daily number of volcano-seismic events was 57, reached during the second anomalous period. This seismicity, characterised by focal depth generally lower than 1?km below sea level (b.s.l.) and composed of different kinds of events associated to both resonance and shear failure processes, is related to the shallow dynamics of the hydrothermal system. During the analysed period, very few volcano-tectonic earthquakes took place and tilt recordings showed no sharp or important changes. In light of such observations, the increases in both temperature and volcano-seismic events number were associated to increases in the release of gas from a deep and stable magma body, without magma intrusions within the shallow hydrothermal system. Indeed, a greater release of gas from depth leads to increased fluid circulation, that can promote increases in volcano-seismic events number by both fracturing processes and resonance and vibration in cracks and conduits. The different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body. Finally, all the observed variations, together with the changing temporal distribution of the different seismic event kinds, suggest that the hydrothermal system at Vulcano can be considered unsteady and dynamic. 相似文献