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41.
G. De Luca R. Scarpa L. Filippi A. Gorini S. Marcucci P. Marsan G. Milana E. Zambonelli 《Journal of Seismology》2000,4(1):1-21
A three-component digital seismic network has been installed along central Apennines since the end of 1991. Two seismic sequences having main shocks of magnitudes 3.9 and 3.7 were recorded in August 1992 and June 1994, respectively. A detailed analysis of these sequences, including multiplet relocation, fault-plane solutions and source parameter estimation, is performed in the present paper. A correlation analysis allowed us to recognize a number of correlated events in the two sequences which were used for relative locations using a master event technique. This analysis allowed to obtain a better alignment of epicentral data along two almost orthogonal directions, following an Apenninic and an anti-Apenninic trend. For the two sequences, fault-plane solutions were evaluated by using a first arrival technique, resulting in mechanisms with predominant normal faulting for the 1992 and 1994 swarms. S-wave polarization analysis allowed to check the stability of the previous solutions and to reduce their range of uncertainty. The same technique was also applied to derive the composite fault-plane solutions from the aftershocks, resulting in solutions which are in good agreement with those derived from the main shocks of both sequences. Source parameters were then derived from the three-component records of 28 well-recorded events with seismic moment in the range 8.5 × 1010–1.0 × 1014 Nm. Stress drops ranged in the interval 0.3–52.3 bar and source radii were of the order of 100 m. Their scaling relations are in good agreement with other results derived from the analysis of other Italian earthquakes that occurred in regions of predominantly normal faulting tectonics (Apennines and Calabrian arc). 相似文献
42.
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
43.
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
44.
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
45.
S��bastien Migeon Antonio Cattaneo Virginie Hassoun Christophe Larroque Nicola Corradi Francesco Fanucci Alexandre Dano Bernard Mercier de Lepinay Fran?oise Sage Christian Gorini 《Marine Geophysical Researches》2011,32(1-2):225-243
Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 108 m3 in volume: Type 1), deep scars 100?C500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are located in different environmental contexts of the margin, including the deep Var Sedimentary Ridge (VSR) and the upper part of the continental slope in the Gulf of Genova (Finale Slide and Portofino Slide), with volumes of missing sediment reaching up to 1.5 × 109 m3. High sedimentation rates related to hyperpycnal flows, faults and earthquake activity, together with sea-level fluctuations are the main factors invoked to explain the distribution and sizes of these different failure types. 相似文献
46.
Ferran Estrada Gemma Ercilla Christian Gorini Bel��n Alonso Juan Tom��s V��zquez Daniel Garc��a-Castellanos Carmen Juan Andr��s Maldonado Abdellah Ammar Mohammed Elabbassi 《Geo-Marine Letters》2011,31(5-6):361-376
The study of more than 500 single- and multichannel seismic records enabled the generation of a detailed palaeo-bathymetric map of the Messinian surface over most of the Alboran Basin, Western Mediterranean. This regional surface is characterized by several erosional features (channels, terraces and canyons) and topographic highs (structural, volcanic and diapiric in origin). The most prominent feature is the incised Zanclean Channel crossing the entire basin, its entrenchment having been associated with the opening of the Strait of Gibraltar and subsequent inflow of Atlantic waters. The incision depth of the channel is variable, suggesting local variations in the erosive capacity of the Atlantic inflow, conditioned mainly by the regional basin topography and the local presence of topographic highs. Adjacent to this channel along the Spanish and Moroccan margins, and near the Strait of Gibraltar, several submarine terraces developed at different depths suggest a pulsed flooding of the Alboran Basin. There could have been two major inflow phases of Atlantic water, one shortly before and another during the Zanclean flooding, the latter accompanied by periods of relative sea-level stillstands that enabled terrace development. Alternatively, these features were all generated during the main flooding evident and subsequent pulsed infilling of the basin. 相似文献
47.
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
48.
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
49.
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
50.
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