Search results for "Pact"
showing 10 items of 2355 documents
Geochemistry of gases and waters discharged by the mud volcanoes at Paternò, Mt. Etna (Italy)
1996
Approximately 20 km south of Mt. Etna craters, at the contact between volcanic and sedimentary formations, three mud volcanoes discharge CO2-rich gases and Na–Cl brines. The compositions of gas and liquid phases indicate that they are fed by a hydrothermal system for which temperatures of 100–150 °C were estimated by means of both gas and solute geothermometry. The hydrothermal system may be associated with CO2-rich groundwaters over a large area extending from the central part of Etna to the mud volcanoes. Numerous data on the He, CH4, CO2 composition of the gases of the three manifestations, sampled over the past 5 years, indicate clearly that variations are due to separation processes of…
The Status of Romanogobio uranoscopus (Agassiz, 1828) Species, in Maramureş Mountains Nature Park (Romania)
2017
Abstract The condition of aquatic habitats typically occupied by Romanogobio uranoscopus within the Maramureş Mountains Natural Park fluctuates, in the best cases, between reduced to average. Good or excellent conservation status is now absent for populations of this species in the researched area. The identified human impact types (poaching, minor riverbeds morphodynamic changes, solid and liquid natural flow changes, destruction of the riparian vegetation and bush vegetation, habitat fragmentation/isolation of population, organic and mining pollution and displaced fish that are washed away during the periodic flooding in the lotic sectors uniformized by humans) are contributing to the dim…
Three-dimensional kernel-based coda attenuation imaging of caldera structures controlling the 1982-84 Campi Flegrei unrest
2019
Abstract Coda-wave attenuation imaging has risen as a state-of-the-art technique to depict volcanic structures using their dispersion effects. The 1982–84 seismic and deformation unrest at Campi Flegrei caldera (Italy) is a unique example of non-eruptive volcanic activity in a structured caldera. Here, we propose the first application of 3D coda-attenuation kernels to image caldera structures at multiple frequencies during unrest. Using sensitivity kernels is necessary to assess the effective resolution of coda imaging in highly heterogeneous volcanoes. The technique relies on the solution of Paasschens' equations in the framework of radiative transfer theory. The results map coda attenuati…
A new approach for the measurement of gaseous elemental mercury (GEM) and H2S in air from anthropogenic and natural sources: Examples from Mt. Amiata…
2017
Real-time measurements of GEM and H2S discharged from natural and anthropogenic sources are a valuable tool to investigate the dispersion dynamics of these contaminants in air. In this study, a new approach to measure GEM and H2S concentrations in air, carried out by coupling a portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) and a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i), was applied to two distinct areas: (i) in the surroundings of Piancastagnaio (Siena, Central Italy), located in the eastern flanks of Mt. Amiata (a 200,000Â years old volcano), where three geothermal plants are operating and whose ex…
Hydraulic properties of fault zones in porous carbonates, examples from central and southern Italy
2016
We present the results of in situ permeability measurements performed, using a portable field permeameter, on normal and strike-slip fault zones that crosscut high-porosity carbonate grainstones. The measurement sites expose in the Cretaceous Orfento Formation of the Majella Mountain (Abruzzo, Italy), and the Lower Pleistocene deposits of the Favignana Island (Sicily, Italy). Nine small-displacement, compactive shear banding-based fault zones have been tested in the field. The fault offset ranges between 10 and 200 centimeters. The acquired permeability data indicate a two orders of magnitude decrease of porosity and permeability from the host rock to the cataclastic fault cores. A clear de…
Chlorine isotope composition of volcanic rocks and gases at Stromboli volcano (Aeolian Islands, Italy): Inferences on magmatic degassing prior to 201…
2017
Abstract Among the magmatic volatiles, chlorine (Cl) is degassed at shallow depths offering the opportunity to investigate the behavior of magmatic degassing close to the surface, and the possible occurrence of chemical and isotopic fractionation related to gas/melt partitioning. However, it is still unclear if the isotopic composition of Cl (δ 37 Cl) can be used as a proxy of magmatic degassing. In this work, we investigate the concentrations of chlorine and sulfur, and the Cl isotope composition of rocks and plume gases collected at Stromboli volcano, Aeolian Islands, Italy. This volcano was chosen because it is characterized by persistent eruptive activity (i.e., Strombolian explosions) …
Fluid circulation at Stromboli volcano (Aeolian Islands, Italy) from self-potential and CO2 surveys
2002
This work addresses the study of fluid circulation of the Stromboli island using a dense coverage of self-potential (SP) and soil CO2 data. A marked difference exists between the northern flank and the other flanks of the island. The northern flank exhibits (1) a typical negative SP/altitude gradient not observed on the other flanks, and (2) higher levels of CO2. The general SP pattern suggests that the northern flank is composed of porous layers through which vadose water flows down to a basal water table, in contrast to the other flanks where impermeable layers impede the vertical flow of vadose water. In the Sciara del Fuoco and Rina Grande–Le Schicciole landslide complexes, breccias of …
Insights into magma and fluid transfer at Mount Etna by a multiparametric approach: A model of the events leading to the 2011 eruptive cycle
2013
[1] Since the second half of the 1990s, the eruptive activity of Mount Etna has provided evidence that both explosive and effusive eruptions display periodic variations in discharge and eruption style. In this work, a multiparametric approach, consisting of comparing volcanological, geophysical, and geochemical data, was applied to explore the volcano's dynamics during 2009–2011. In particular, temporal and/or spatial variations of seismicity (volcano-tectonic earthquakes, volcanic tremor, and long-period and very long period events), ground deformation (GPS and tiltmeter data), and geochemistry (SO2 flux, CO2 flux, CO2/SO2 ratio) were studied to understand the volcanic activity, as well as…
The summit hydrothermal system of Stromboli: New insights from self-potential, temperature, CO2 and fumarolic fluids measurements, with structural an…
2003
International audience; Accurate and precisely located self-potential (SP), temperature (T) and COi measurements were carried out in the summit area of Stromboli along 72 straight profiles. SP data were acquired every metre and T data every 2.5 m. CO2 concentrations were acquired with the same density as T, but only along seven profiles. The high density of data and the diversity of the measured parameters allows us to study structures and phenomena at a scale rarely investigated. The shallow summit hydrothermal activity (Pizzo-Fossa area) is indicated by large positive SP, T and COi anomalies. These anomalies are focused on crater faults, suggesting that the fracture zones are more permeab…
Pathways and fate of REE in the shallow hydrothermal aquifer of Vulcano island (Italy)
2019
Abstract We investigated the geochemical behaviour of major and Rare Earth Elements (REE), together with oxygen and deuterium isotopic composition in the aquifer of Vulcano, the southernmost island of the Aeolian archipelago (Italy). Studied wells, located at different distances from the crater, are characterised by different contributions of the rising volcanic fluids. In particular, those located in the proximity of La Fossa crater are affected by a strong interaction with volcanic-hydrothermal fluids and show REE behaviour similar to that of fresh rocks, suggesting a congruent dissolution of the solid matrix. Samples from the other wells, located in an area where the volcanic deposits ar…