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61.
Alessandro Bonforte Salvatore Gambino Francesco Guglielmino Francesco Obrizzo Mimmo Palano Giuseppe Puglisi 《Bulletin of Volcanology》2007,69(7):757-768
On 22 September 2002, 1 month before the beginning of the flank eruption on the NE Rift, an M-3.7 earthquake struck the northeastern
part of Mt. Etna, on the westernmost part of the Pernicana fault. In order to investigate the ground deformation pattern associated
with this event, a multi-disciplinary approach is presented here. Just after the earthquake, specific GPS surveys were carried
out on two small sub-networks, aimed at monitoring the eastern part of the Pernicana fault, and some baselines belonging to
the northeastern EDM monitoring network of Mt. Etna were measured. The leveling route on the northeastern flank of the volcano
was also surveyed. Furthermore, an investigation using SAR interferometry was performed and also the continuous tilt data
recorded at a high precision sensor close to the epicenter were analyzed to constrain the coseismic deformation. The results
of the geodetic surveys show a ground deformation pattern that affects the entire northeastern flank of the volcano, clearly
shaped by the Pernicana fault, but too strong and wide to be related only to an M-3.7 earthquake. Leveling and DInSAR data
highlight a local strong subsidence, up to 7 cm, close to the Pernicana fault. Significant displacements, up to 2 cm, were
also detected on the upper part of the NE Rift and in the summit craters area, while the displacements decrease at lower altitude,
suggesting that the dislocation did not continue further eastward. Three-dimensional GPS data inversions have been attempted
in order to model the ground deformation source and its relationship with the volcano plumbing system. The model has also
been constrained by vertical displacements measured by the leveling survey and by the deformation map obtained by SAR interferometry. 相似文献
62.
Salvatore Giammanco Massimo Ottaviani Enrico Veschetti 《Pure and Applied Geophysics》2007,164(12):2523-2547
Data for major, minor and trace elements in groundwaters from Mt. Etna volcano collected in 1994, 1995 and 1997 were analyzed
using Cluster Analysis (CA). Two groups of sampling sites were identified (named clusters A and B), mainly on the basis of
their different salinity and content of dissolved CO2. The highest levels of both of these parameters were observed in the sites of cluster A, located in the lower south-western
and central eastern flanks of the volcano. For both of the statistical groups CA was repeated, taking into account the mean
values of each parameter in time, and the results allowed us to recognize four distinct groups of parameters for each group
of sites on the basis of their temporal patterns. Four different types of temporal patterns were recognized: concave, convex,
increasing, decreasing. The observed changes were basically interpreted as a result of the different response of dissolved
chemical elements to changes in the aqueous environment and/or in their solubility/mobility in water due to different rates
of input of magmatic gases to Etna’s aquifers. The main changes occurred in 1995, when Etna’s volcanic activity resumed after
a two-year period of rest. The temporal changes of the majority of the studied parameters (water temperature, water conductivity,
Eh, pH, Al, Mg, B, Ca, Cl−, Hg, Mn, Mo, Na, Ni, Se, Si, Sr, Cr Zn and pCO2) were not cluster-dependent, therefore they were not apparently affected by differences in water salinity between the two
groups of sampling sites. A limited number of parameters (Ti, K, Li, HCO3−, As, Fe, SO42−, Cu and V), however, manifested different behaviors, depending on the cluster of sites to which they belonged, thus suggesting
their apparent dependency on water salinity. 相似文献
63.
Antonino D’Andrea Salvatore Cafiso Antonio Condorelli 《Pure and Applied Geophysics》2005,162(4):767-782
The recent earthquakes in California and Japan have shown the fundamental role that the road infrastructure plays in emergencies. In fact, only the maintenance of a sufficient level of efficiency can help to quickly reach the affected areas and thus avoid further serious consequences. The necessity of guaranteeing the functionality of the transport network during seismic events therefore requires seismic risk planning extended also to the road infrastructures in order to support the management of post-earthquake emergencies. Analogously it is fundamentally important to have analysis instruments of the road system able to preventatively evaluate the effects of earthquakes in order to identify possible emergencies, therefore preparing a program of intervention to reduce seismic risk on road networks. This paper proposes a methodology for the evaluation of seismic risk of road infrastructures according to the following points:Study of seismic hazard of the site for the definition of a seismic scenario using attenuation models in relation to historical seismology and the geological and tectonic characteristics of the territory;Analysis of the direct exposure connected to the probability of the presence of road users on the different parts of the network directly exposed to the seismic event;Analysis of the indirect exposure relative to the distribution of the population and the infrastructures for which post-earthquake accessibility must be guaranteed;Evaluation of the functional vulnerability in relation to the potential replaceability of damaged stretches considering network configuration and geometrical characteristics;Evaluation of structural vulnerability of the stretch correlated to the characteristics (structural, mechanical, technological, etc.) of the different components (bridges, embankments, trenches, tunnels) that make up the stretches obtained by the use of correctly elaborated tables for each component.The determination of global risk indexes of the single stretches and of the network, evaluated by means of a relationship between the ascertained parameters derived from the investigation of the previous points, provides the necessary information for the definition of mitigation measures to reduce the risk and for management planning before and after disaster. The proposed methodology, which has already been applied to a restricted area, is currently being applied to the province of Catania (Sicily, Italy), which is one of the geographical regions of highest seismic risk in Europe, and its future extension to all of eastern Sicily is foreseeable. 相似文献
64.
65.
Salvatore de Lorenzo Elisabetta Giampiccolo Carmen Martinez-Arevalo Domenico Patanè Annalisa Romeo 《Journal of Volcanology and Geothermal Research》2010,189(3-4):247-256
A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 low-magnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002–2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the “true” fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies. 相似文献
66.
We extend the analysis of the thermodynamics of the climate system by investigating the role played by processes taking place at various spatial and temporal scales through a procedure of coarse graining. We show that the coarser is the graining of the climatic fields, the lower is the resulting estimate of the material entropy production. In other terms, all the spatial and temporal scales of variability of the thermodynamic fields provide a positive contribution to the material entropy production. This may be interpreted also as that, at all scales, the temperature fields and the heating fields resulting from the convergence of turbulent fluxes have a negative correlation, while the opposite holds between the temperature fields and the radiative heating fields. Moreover, we obtain that the latter correlations are stronger, which confirms that radiation acts as primary driver for the climatic processes, while the material fluxes dampen the resulting fluctuations through dissipative processes. We also show, using specific coarse-graining procedures, how one can separate the various contributions to the material entropy production coming from the dissipation of kinetic energy, the vertical sensible and latent heat fluxes, and the large scale horizontal fluxes, without resorting to the full three-dimensional time dependent fields. We find that most of the entropy production is associated to irreversible exchanges occurring along the vertical direction, and that neglecting the horizontal and time variability of the fields has a relatively small impact on the estimate of the material entropy production. The approach presented here seems promising for testing climate models, for assessing the impact of changing their parametrizations and their resolution, as well as for investigating the atmosphere of exoplanets, because it allows for evaluating the error in the estimate of their thermodynamical properties due to the lack of high-resolution data. The findings on the impact of coarse graining on the thermodynamic fields on the estimate of the material entropy production deserve to be explored in a more general context, because they provide a way for understanding the relationship between forced fluctuations and dissipative processes in continuum systems. 相似文献
67.
Salvatore Pascale Jonathan M. Gregory Maarten Ambaum Rémi Tailleux 《Climate Dynamics》2011,36(5-6):1189-1206
The entropy budget is calculated of the coupled atmosphere–ocean general circulation model HadCM3. Estimates of the different entropy sources and sinks of the climate system are obtained directly from the diabatic heating terms, and an approximate estimate of the planetary entropy production is also provided. The rate of material entropy production of the climate system is found to be ~50 mW m?2 K?1, a value intermediate in the range 30–70 mW m?2 K?1 previously reported from different models. The largest part of this is due to sensible and latent heat transport (~38 mW m?2 K?1). Another 13 mW m?2 K?1 is due to dissipation of kinetic energy in the atmosphere by friction and Reynolds stresses. Numerical entropy production in the atmosphere dynamical core is found to be about 0.7 mW m?2 K?1. The material entropy production within the ocean due to turbulent mixing is ~1 mW m?2 K?1, a very small contribution to the material entropy production of the climate system. The rate of change of entropy of the model climate system is about 1 mW m?2 K?1 or less, which is comparable with the typical size of the fluctuations of the entropy sources due to interannual variability, and a more accurate closure of the budget than achieved by previous analyses. Results are similar for FAMOUS, which has a lower spatial resolution but similar formulation to HadCM3, while more substantial differences are found with respect to other models, suggesting that the formulation of the model has an important influence on the climate entropy budget. Since this is the first diagnosis of the entropy budget in a climate model of the type and complexity used for projection of twenty-first century climate change, it would be valuable if similar analyses were carried out for other such models. 相似文献
68.
Agnes Mazot Dmitri Rouwet Yuri Taran Salvatore Inguaggiato Nick Varley 《Bulletin of Volcanology》2011,73(4):423-441
During 2007–2008, three CO2 flux surveys were performed on El Chichón volcanic lake, Chiapas, Mexico, with an additional survey in April 2008 covering
the entire crater floor (including the lake). The mean CO2 flux calculated by sequential Gaussian simulation from the lake was 1,190 (March 2007), 730 (December 2007) and 1,134 g m−2 day−1 (April 2008) with total emission rates of 164 ± 9.5 (March 2007), 59 ± 2.5 (December 2007) and 109 ± 6.6 t day−1 (April 2008). The mean CO2 flux estimated from the entire crater floor area was 1,102 g m−2 day−1 for April 2008 with a total emission rate of 144 ± 5.9 t day−1. Significant change in CO2 flux was not detected during the period of survey, and the mapping of the CO2 flux highlighted lineaments reflecting the main local and regional tectonic patterns. The 3He/4He ratio (as high as 8.1 R
A) for gases in the El Chichón crater is generally higher than those observed at the neighbouring Transmexican Volcanic Belt
and the Central American Volcanic Arc. The CO2/3He ratios for the high 3He/4He gases tend to have the MORB-like values (1.41 × 109), and the CO2/3He ratios for the lower 3He/4He gases fall within the range for the arc-type gases. The high 3He/4He ratios, the MORB-like CO2/3He ratios for the high 3He/4He gases and high proportion of MORB-CO2 (M = 25 ±15%) at El Chichón indicate a greater depth for the generation of magma when compared to typical arc volcanoes. 相似文献
69.
70.
Salvatore Inguaggiato Fabio Vita Dmitri Rouwet Nicole Bobrowski Sabina Morici Aldo Sollami 《Bulletin of Volcanology》2011,73(4):443-456
On 27 February 2007, a new eruption occurred on Stromboli which lasted until 2 April. It was characterized by effusive activity
on the Sciara del Fuoco and by a paroxysmal event (15 March). This crisis represented an opportunity for us to refine the
model that had been developed previously (2002–2003 eruption) and to improve our understanding of the relationship between
the magmatic dynamics of the volcano and the geochemical variations in the fluids. In particular, the evaluation of the dynamic
equilibrium between the volatiles (CO2 and SO2) released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of
criticality of the volcanic activity. One of the major accomplishments of this study is a 4-year database of summit soil CO2 flux on the basis of which we define the thresholds (low–medium–high) for this parameter that are empirically based on the
natural volcanological evolution of Stromboli. The SO2 fluxes of the degassing plume and the CO2 fluxes emitted from the soil at Pizzo Sopra la Fossa are also presented. It is noteworthy that geochemical signals of volcanic
unrest have been clearly identified before, during and after the effusive activity. These signals were found almost simultaneously
in the degassing plume (SO2 flux) and in soil degassing (CO2 flux) at the summit, although the two degassing processes are shown to be clearly different. The interpretation of the results
will be useful for future volcanic surveillance at Stromboli. 相似文献