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31.
Antonella Amoruso Luca Crescentini Marco Petitta Sergio Rusi Marco Tallini 《水文研究》2011,25(11):1754-1764
The Mw = 6·3 L'Aquila earthquake on 6 April 2009 produced a mainshock that caused significant changes in the hydrogeology of the Gran Sasso carbonate fractured aquifer: (i) the sudden disappearance at the time of the mainshock of some springs located exactly along the surface trace of the Paganica normal fault (PF); (ii) an immediate increase in the discharge of the Gran Sasso highway tunnel drainages and of other springs and (iii) a progressive increase of the water table elevation at the boundary of the Gran Sasso aquifer during the following months. Using the data collected since the 1990s that include aftershock monitoring as well as data regarding spring discharge, water table elevations, turbidity and rainfall events, a conceptual model of the earthquake's consequences on the Gran Sasso aquifer is proposed herein. In this model that excludes the contribution of seasonal recharge, the short‐term hydrologic effects registered immediately after the mainshock are determined to have been caused by a pore pressure increase related to aquifer deformation. Mid‐term effects observed in the months following the mainshock suggest that there was a change in groundwater hydrodynamics. Supplementary groundwater that flows towards aquifer boundaries and springs in discharge areas reflects a possible increase in hydraulic conductivity in the recharge area, nearby the earthquake fault zone. This increase can be attributed to fracture clearing and/or dilatancy. Simulations by numerical modelling, related to pore pressure and permeability changes with time, show results in accordance with observed field data, supporting the conceptual model and confirming the processes that influenced the answer of the Gran Sasso aquifer to the L'Aquila earthquake. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
32.
Claudia?D’OrianoEmail author Antonella?Bertagnini Massimo?Pompilio 《Bulletin of Volcanology》2011,73(5):471-477
Ash fallout collected during 4 days of sampling at Stromboli confirms that a crystal-rich (HP) degassed magma erupts during
the Strombolian explosions that are characteristic of the normal activity of this volcano. We identified 3 different types
of juvenile ash fragments (fluidal, spongy and dense), which formed through different mechanisms of fragmentation of the low-viscosity,
physically heterogeneous (in terms of the size and spatial distribution of bubbles) shoshonitic magma. A small amount (less
than 3 vol%) of volatile-rich magma with low porphyricity (LP), erupted as highly vesicular ash fragments, has been collected,
together with the HP magma, during normal strombolian explosions. Laboratory experiments and the morphological, textural and
compositional investigations of ash fragments reveal that the LP ash is fresh and not recycled from the last paroxysm (15
March 2007). We suggest that small droplets of LP magma are dragged to the surface by the time-variable but persistent supply
of deep derived CO2-rich gas bubbles. This coupled ascent of bubbles and LP melts is transient and does not perturb the dynamics of the HP magma
within the shallow reservoir. This finding provides a new perspective on how the Stromboli volcano works and has important
implications for monitoring strategies. 相似文献
33.
Overview of the Italian strong motion database ITACA 1.0 总被引:3,自引:2,他引:1
Francesca Pacor Roberto Paolucci Lucia Luzi Fabio Sabetta Andrea Spinelli Antonella Gorini Mario Nicoletti Sandro Marcucci Luisa Filippi Mauro Dolce 《Bulletin of Earthquake Engineering》2011,9(6):1723-1739
The Italian Strong Motion Database, ITACA, was developed within projects S6 and S4, funded in the framework of the agreements
between the Italian Department of Civil Protection (Dipartimento della Protezione Civile, DPC) and the Istituto Nazionale
di Geofisica e Vulcanologia (INGV), starting from 2005. The alpha version of the database was released in 2007 and subsequently
upgraded to version 1.0 after: (i) including the most recent strong motion data (from 2005 to 2007) recorded in Italy, in
addition to the 2008 Parma earthquake, M 5.4, and the M ≥ 4.0, 2009 Abruzzo seismic events; (ii) processing the raw strong
motion data using an updated procedure; (iii) increasing the number of stations with a measured shear wave velocity profile;
(iv) improving the utilities to retrieve time series and ground motion parameters; (v) implementing a tool for selecting time
series in agreement with design-response spectra; (vi) compiling detailed station reports containing miscellaneous information
such as photo, maps and site parameters; (vii) developing procedures for the automatic generation of station reports and for
the updating of the header files. After such improvements, ITACA 1.0 was published at the web site , in 2010. It presently contains 3,955 three-component waveforms, comprising the most complete catalogue of the Italian accelerometric
records in the period 1972–2007 (3,562 records) and the strongest events in the period 2008–2009. Records were mainly acquired
by DPC through its Accelerometric National Network (RAN) and, in few cases, by local networks and temporary stations or networks.
This paper introduces the published version of the Italian Strong Motion database (ITACA version 1.0) together with main improvements
and new functionalities. 相似文献
34.
Belskaya Irina N. Barucci Antonella M. Shkuratov Yurij G. 《Earth, Moon, and Planets》2003,92(1-4):201-206
Information on the surface structure of the Kuiper Belt objectscan be obtained from studies of their opposition brightening.Although KBOs are observed at a very limited phase angle rangethey represent a unique opportunity to study the backscatteringphenomenon down almost to zero phase angle. Preliminaryestimations of the opposition effect amplitude and width based oncomposite phase curves of four KBOs and two Centaurs showed theexistence of a very narrow opposition surge of about 0.1–0.2 mag at phase angles less than 0.1–0.2 deg. It may indicate a highporosity of the KBOs regoliths. Further observations are needed toconfirm this phenomenon. 相似文献
35.
Boehnhardt Hermann Barucci Antonella Delsanti Audrey De Bergh Catherine Doressoundiram Alain Romon Jennifer Dotto Elisabetta Tozzi Gianpaolo Lazzarin Monica Fornasier Sonia Peixinho Nuno Hainaut Olivier Davies John Rousselot Philippe Barrera Luis Birkle Kurt Meech Karen Ortiz JoseLuis Sekiguchi Tomohiko Watanabe Jun-ichi Thomas Nick West Richard 《Earth, Moon, and Planets》2003,92(1-4):145-156
BVRI photometry of 107 TNOs and Centaurs establishes the range of spectral gradients to be between –5 to 55%/100 nm (with one exception). A cluster of very red Cubewanos is firmly identified in orbits of low inclination and eccentricity beyond 40 AU from the Sun. Further correlations between surface colours and dynamical parameters (inclination and perihelion distance) are suggested for Cubewanos and scattered disk objects, but lack complete confidence for their reality. Plutinos and Centaurs do not show any clear correlation between surface colours and orbital parameters. We present in this paper 12 spectra obtained in the visible region and nine of them for which we obtained also near infrared spectra up to 2.4 microns. A few other objects have been observed, but the data are still under reduction and analysis. The principal reported results obtained are: (i) a wide range of visible slopes; (ii) evidence for surface variations on 2001 PT13; and (iii) possible detection of few percent of water ice (1999 TC36}, 2000 EB173, 1999 DE9, 2001 PT13, 2000 QC243, 1998 SG35). 相似文献
36.
Ilian T. Iliev Benedetta Ciardi Marcelo A. Alvarez Antonella Maselli rea Ferrara Nickolay Y. Gnedin Garrelt Mellema Taishi Nakamoto Michael L. Norman Alexei O. Razoumov Erik-Jan Rijkhorst Jelle Ritzerveld Paul R. Shapiro Hajime Susa Masayuki Umemura Daniel J. Whalen 《Monthly notices of the Royal Astronomical Society》2006,371(3):1057-1086
Radiative transfer (RT) simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time their computational cost has come within reach of currently available computational power. Further progress is retarded by the considerable number of different algorithms (including various flavours of ray tracing and moment schemes) developed, which makes the selection of the most suitable technique for a given problem a non-trivial task. Assessing the validity ranges, accuracy and performances of these schemes is the main aim of this paper, for which we have compared 11 independent RT codes on five test problems: (0) basic physics; (1) isothermal H ii region expansion; (2) H ii region expansion with evolving temperature; (3) I-front trapping and shadowing by a dense clump and (4) multiple sources in a cosmological density field. The outputs of these tests have been compared and differences analysed. The agreement between the various codes is satisfactory although not perfect. The main source of discrepancy appears to reside in the multifrequency treatment approach, resulting in different thicknesses of the ionized-neutral transition regions and the temperature structure. The present results and tests represent the most complete benchmark available for the development of new codes and improvement of existing ones. To further this aim all test inputs and outputs are made publicly available in digital form. 相似文献
37.
The impact of groundwater withdrawals on the interaction between multi-layered aquifers with different water qualities in the Viterbo geothermal area (central Italy) was studied. In this area, deep thermal waters are used to supply thermal spas and public pools. A shallow overlying aquifer carries cold and fresh water, used for irrigation and the local drinking-water supply. Starting with a conceptual hydrogeological model, two simplified numerical models were implemented: a steady-state flow model of the entire groundwater system, and a steady-state flow and heat transport model of a representative area, which included complex interactions between the aquifers. The impact of increased withdrawals associated with potential future development of the thermal aquifer must be considered in terms of the water temperature of the existing thermal sources. However, withdrawals from the shallow aquifer might also influence the discharge of thermal sources and quality of the water withdrawn from the shallow wells. The exploitation of the two aquifers is dependent on the hydraulic conductivity and thickness of the intervening aquitard, which maintains the delicate hydrogeological equilibrium. Effective methods to control this equilibrium include monitoring the vertical gradient between the two aquifers and the residual discharge of natural thermal springs. 相似文献
38.
There is a need to elucidate the impact of ethanol on the subsurface environment because of the application of ethanol as automotive fuel. This study quantifies the effects of changes in surface tension, viscosity, and density induced by ethanol on the transmission and retention of water in the vadose zone. The HYDRUS‐1D model was modified to simulate two different scenarios of flow in a sandy loam involving ponding (constant head) or spillage with a subsequent rainfall event (constant flux). Solutions containing different amounts of the highly miscible ethanol (10, 50, and 100% by weight) as well as pristine water were considered. During ponding, ethanol reduced the amount of fluid entering the soil and slowed down the advancement of the wetting front. Viscosity effects were predominant for this scenario, reducing the average depth of the infiltrating liquid up to 44%. The total amount of pure ethanol that entered the soil was 11.38 vs. 17.64 cm for pure water. For the spillage scenario, the results suggest that density has little impact on the liquid movement. Surface tension effects are predominant in the upper portion of the soil. The changes in hydraulic conductivity due to ethanol‐induced modifications of solution viscosity are responsible for the slower advancement of the moisture front. The 10% ethanol solution moved 43.1% faster than pure ethanol during the first 2 d because of viscosity and surface tension effects. 相似文献
39.
We examined changes at the community and population level of sedimentary diatoms over a wide temporal and spatial gradient
of metal pollution encountered in cores from three lakes in the Abitibi mining region (Québec, Canada). Diatom communities
on the whole appeared to be very tolerant of metal contamination, as shown by diatom cell accumulation rates decreasing only
under the most severe conditions of contamination, which were found from the 1930s to the 1980s in Lac Dufault (cadmium, up
to 94 μg/g dry sediment; Cu, up to 8600 μg/g; Zn, up to 9000 μg/g). Under the moderate conditions of contamination observed
in the other two lakes and in the most recent sediment of Lac Dufault, diatom cell accumulation rates tended to increase over
values typical of the pre-mining period. However, there were increasing rearrangements of the community composition along
the contamination gradient. Under moderate metal enrichment, the diatom community of Lac Vaudray experienced only subtle changes,
with Cyclotella stelligera, albeit decreasing, remaining the dominant taxon. In the intermediately contaminated Lac Caron, several benthic taxa, noticeably
Cymbella silesiaca and several Fragilaria species, rose in taxonomic importance. The most extreme contamination observed in Lac Dufault led to a severely impoverished
community almost entirely represented by Achnanthes minutissima and Brachysira vitrea. With increasing levels of contamination, there was a shift from planktonic to benthic taxa and morphotypes and a consistent
decrease in the siliceous stomatocysts/diatom frustules ratio. These trends suggest that littoral zones may represent an
important refugium under conditions of high contamination. Responses to metal stress were in general more evident at the population
than at the community level. Cyclotella stelligera and B. vitrea had a consistent negative and positive response, respectively, along the gradient and are the most promising indicators of
metal pollution for this region. 相似文献
40.