ALBERT

Beschreibung: In questo lavoro si presentano i risultati di uno studio sulle caratteristiche del rumore sismico in prossimità del rilevatore di onde gravitazionali VIRGO (Cascina, Pisa), con particolare riferimento alle vibrazioni associate all’azione di un vicino parco eolico. La valutazione delle componenti spettrali del rumore verosimilmente indotte dagli aerogeneratori è stata effettuata mediante (i) Misure dirette alla base di una turbina, (ii) Correlazione fra le ampiezze spettrali del rumore e la velocità del vento; (iii) Determinazione delle proprietà direzionali da misure multicanale, (iv) Misura dell’attenuazione del segnale con la distanza dal parco eolico. Il disturbo provocato dagli aerogeneratori è particolarmente energetico alla frequenza di 1.7 Hz e, in particolari condizioni, è stato osservato fino a distanze di 11 km dal Parco Eolico. Il decadimento spaziale delle ampiezze ha un andamento complesso, che può essere interpretato in termini di una combinazione fra onde superficiali e onde di volume rifratte ad un’interfaccia profonda (~800 m) fra i sedimenti plio-pleistocenici ed i calcari Miocenici. La risposta locale nei dintorni dell’interferometro è stata investigata utilizzando la tecnica dei rapporti spettrali H/V. Si sono così evidenziate due bande di amplificazione imputabili ad effetti di risonanza legati alla geologia a scala locale: il primo intorno alla frequenza di 0.35 Hz, il secondo fra 0.7 e 2.0 Hz. Entrambi i picchi risultano essere essenzialmente omogenei in tutta l’area di studio, a conferma della sostanziale uniformità della struttura geologica.

Beschreibung: Published

Beschreibung: 1-30

Beschreibung: 1.1. TTC - Monitoraggio sismico del territorio nazionale

Beschreibung: N/A or not JCR

Beschreibung: open

Beschreibung: BREVIA

Beschreibung: We report on the discovery in southern Egypt of an impact crater 45 m in diameter with a pristine rayed structure. Such pristine structures have been previously observed only on atmosphereless rocky or icy planetary bodies in the Solar System. This feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small-scale hypervelocity impacts on the Earth's crust. Contrary to current geophysical models, ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without significant fragmentation.

Beschreibung: Published

Beschreibung: 804

Beschreibung: 1.8. Osservazioni di geofisica ambientale

Beschreibung: 3.8. Geofisica per l'ambiente

Beschreibung: JCR Journal

Beschreibung: open

Beschreibung: Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after carbon dioxide. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former (IPCC, 2007). It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere (Etiope, 2004). Active or recent volcanic/geothermal areas represent one of these sources of geological methane. But due to the fact that methane flux measurements are laboratory intensive, very few data have been collected until now and the contribution of this source has been generally indirectly estimated (Etiope et al., 2007). The Greek territory is geodynamically very active and has many volcanic and geothermal areas. Here we report on methane flux measurements made at two volcanic/geothermal systems along the South Aegean volcanic arc: Sousaki and Nisyros. The former is an extinct volcanic area of Plio-Pleistocene age hosting nowadays a low enthalpy geothermal field. The latter is a currently quiescent active volcanic system with strong fumarolic activity due to the presence of a high enthalpy geothermal system. Both systems have gas manifestations that emit significant amounts of hydrothermal methane and display important diffuse carbon dioxide emissions from the soils. New data on methane isotopic composition and higher hydrocarbon contents point to an abiogenic origin of the hydrothermal methane in the studied systems. Measured methane flux values range from –48 to 29,000 (38 sites) and from –20 to 1100 mg/mˆ2/d (35 sites) at Sousaki and Nisyros respectively. At Sousaki measurement sites covered almost all the degassing area and the diffuse methane output can be estimated in about 20 t/a from a surface of about 10,000 mˆ2. At Nisyros measurements covered the Stephanos and Kaminakia areas, which represent only a part of the entire degassing area. The two areas show very different methane degassing pattern with latter showing much higher flux values. Methane output can be estimated in about 0.25 t/a from an area of about 30,000 mˆ2 at Stephanos and about 1 t/a from an area of about 20,000 mˆ2 at Kaminakia. The total output from the entire geothermal system of Nisyros probably should not exceed 2 t/a.

Beschreibung: Published

Beschreibung: Vienna, Austria

Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi

Beschreibung: open

Beschreibung: A biomonitoring survey, above tree line level, using two endemic species (Senecio aethnensis and Rumex aethnensis) was performed on Mt. Etna, in order to evaluate the dispersion and the impact of volcanic atmospheric emissions. Samples of leaves were collected in summer 2008 from 30 sites in the upper part of the volcano (1500- 3000 m a.s.l). Acid digestion of samples was carried out with a microwave oven, and 44 elements were analyzed by using plasma spectrometry (ICP-MS and ICP-OES). The highest concentrations of all investigated elements were found in the samples collected closest to the degassing craters, and in the downwind sector, confirming that the eastern flank of Mt. Etna is the most impacted by volcanic emissions. Leaves collected along two radial transects from the active vents on the eastern flank, highlight that the levels of metals decrease one or two orders of magnitude with increasing distance from the source. This variability is higher for volatile elements (As, Bi, Cd, Cs, Pb, Sb, Tl) than for more refractory elements (Al, Ba, Sc, Si, Sr, Th, U). The two different species of plants do not show significant differences in the bioaccumulation of most of the analyzed elements, except for lanthanides, which are systematically enriched in Rumex leaves. The high concentrations of many toxic elements in the leaves allow us to consider these plants as highly tolerant species to the volcanic emissions, and suitable for biomonitoring researches in the Mt. Etna area.

Beschreibung: Published

Beschreibung: Vienna, Austria

Beschreibung: 4.4. Scenari e mitigazione del rischio ambientale

Beschreibung: open

Beschreibung: Etna volcano, Italy, hosts one of the major groundwater systems of the island of Sicily. Waters circulate within highly permeable fractured, mainly hawaiitic, volcanic rocks. Aquifers are limited downwards by the underlying impermeable sedimentary terrains. Thickness of the volcanic rocks generally does not exceed some 300 m, preventing the waters to reach great depths. This is faced by short travel times (years to tens of years) and low thermalisation of the Etnean groundwaters. Measured temperatures are, in fact, generally lower than 25 °C. But the huge annual meteoric recharge (about 0.97 kmˆ3) with a high actual infiltration coefficient (0.75) implies a great underground circulation. During their travel from the summit area to the periphery of the volcano, waters acquire magmatic heat together with volcanic gases and solutes through water-rock interaction processes. In the last 20 years the Etnean aquifers has been extensively studied. Their waters were analysed for dissolved major, minor and trace element, O, H, C, S, B, Sr and He isotopes, and dissolved gas composition. These data have been published in several articles. Here, after a summary of the obtained results, the estimation of the magmatic heat flux through the aquifer will be discussed. To calculate heat uptake during subsurface circulation, for each sampling point (spring, well or drainage gallery) the following data have been considered: flow rate, water temperature, and oxygen isotopic composition. The latter was used to calculate the mean recharge altitude through the measured local isotopic lapse rate. Mean recharge temperatures, weighted for rain amount throughout the year, were obtained from the local weather station network. Calculations were made for a representative number of sampling points (216) including all major issues and corresponding to a total water flow of about 0.315 kmˆ3/a, which is 40% of the effective meteoric recharge. Results gave a total energy output of about 140 MW/a the half of which is ascribable to only 13 sampling points. These correspond to the highest flow drainage galleries with fluxes ranging from 50 to 1000 l/s and wells with pumping rates from 70 to 250 l/s. Geographical distribution indicates that, like magmatic gas leakage, heat flow is influenced by structural features of the volcanic edifice. The major heat discharge through groundwater are all tightly connected either to the major regional tectonic systems or to the major volcanic rift zones along which the most important flank eruptions take place. But rift zones are much more important for heat upraise due to the frequent dikes injection than for gas escape because generally when dikes have been emplaced the structure is no more permeable to gases because it becomes sealed by the cooling magma.

Beschreibung: Published

Beschreibung: Vienna, Austria

Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Beschreibung: open

Beschreibung: Questo lavoro illustra lo stato della Rete Sismica Nazionale Italiana e descrive la sismicità italiana nell’anno 2009. Vengono evidenziate le principali sequenze sismiche occorse durante l’anno, con particolare riguardo alla sequenza sismica dell’aquilano-reatino. Nel 2009 la Rete Sismica Nazionale dell’INGV ha registrato circa 26000 terremoti avvenuti sul territorio nazionale e nelle aree limitrofe, che sono stati analizzati e localizzati dal gruppo di analisti sismologi che si occupano della redazione del Bollettino Sismico Italiano (BSI). La magnitudo minima di completezza Mc del BSI 2009, ovvero la soglia di magnitudo minima media calcolata su tutto il territorio nazionale, è risultata pari a ML 1.6 (il dato del BSI 2008 si attestava sul valore di ML 2.1). Il numero di stazioni sismiche attive (Rete Nazionale e reti locali) nel corso del 2009 è stato di 305 (279 nel 2008). Viene fornita infine una stima del numero e della magnitudo di eventi di origine antropica (esplosioni) presenti nel BSI 2009. This paper describes the status of the Italian National Seismic Network and the Italian seismicity in year 2009. We outline the main seismic sequences that occurred during the year, with particular emphasis on the L’Aquila-Rieti seismic period. The INGV National Seismic Network recorded about 26000 earthquakes in Italy and neighboring areas during 2009, which were analyzed and localized by the seismology group of analysts involved in the publication of the Italian Seismic Bulletin (BSI). The minimum magnitude of completeness Mc of the BSI 2009 is ML 1.6 (ML 2.1 in the BSI 2008). The number of active seismic stations during 2009 was 305 (279 in 2008). We provide an estimate of the number and magnitude of anthropic events (quarry-blasts) included in the BSI 2009.

Beschreibung: Published

Beschreibung: 1-52

Beschreibung: 5.2. TTC - Banche dati di sismologia strumentale

Beschreibung: N/A or not JCR

Beschreibung: open

Beschreibung: Volcanic emissions are considered one of the major natural sources of several trace metals (e.g. As, Cd, Cu, Pb, and Zn) to the atmosphere [Nriagu, 1989], and the geochemical cycles of these elements have to be considered strongly influenced by volcanic input. However, the accurate estimation of the global volcanic emissions of volatile trace metals into the atmosphere is still affected by a high level of uncertainty. The latter depends on the large variability in the emission of the different volcanoes, and on their changing stage of activity. Moreover, only few of the potential sources in the world have been directly measured [Hinkley et al. 1999]. Atmospheric deposition processes (wet and dry) are the pathways through which volcanic emissions return to the ground (soils, plants, aquifers), resulting in both harmful and beneficial effects [Baxter et al. 1982; Aiuppa et al. 2000; Brusca et al. 2001; Delmelle, 2003; Bellomo et al. 2007; Martin et al. 2009; Floor et al. 2011; Calabrese et al. 2011]. In the first part of this study we present the results of a literature review on trace metals emissions from active volcanoes around the world. In the second part, we present new data on the fluxes of the trace metals from Etna (Italy) and four active volcanoes in the world: Turrialba (Costarica), Nyiragongo (DRC), Mutnovsky and Gorely (Kamchatka). We found 27 publications (the first dating back to the 70’s), 13 of which relate to the Etna and the other include some of the world’s most active volcanoes: Mt. St. Helens, Erebus, Merapi, White Island, Kilauea, Popocatepetl, Galeras, Indonesian arc, Satasuma and Masaya. The review shows that currently there are very few data available, and that the most studied volcano is Mt. Etna. Using these data, we defined a range of fluxes for As, Ba, Bi, Cd, Cu, Fe, Mn, Pb, Se, V and Zn (Figure 1). To obtain new data we sampled particulate filters at the five above mentioned volcanoes. Filters were mineralized (acid digestion) and analyzed by ICP-MS. Sulphur to trace element ratios were related to sulphur fluxes to indirectly estimate trace elements fluxes. Etna confirms to be one of the greatest point sources in the world. The Nyiragongo results to be also a significant source of metals to the atmosphere, especially considering its persistent state of degassing from the lava lake. Also Turrialba and Gorely have high emission rates of trace metals considering the global range. Only Mutnovsky Volcano show values which are sometimes lower than the range obtained from the review, consistent with the fact that it is mainly a fumarolic field. This work highlights the need to expand the current dataset including many other active volcanoes for a better constraint of global trace metal fluxes from active volcanoes.

Beschreibung: Published

Beschreibung: Nicolosi (Catania)

Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Beschreibung: open

Beschreibung: Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere, both during and between eruptions. Due to their potential toxicity they may have important environmental impacts from the local to the global scale. Mount Etna, the largest European volcano and one of the most active volcano in the world, covers an area of about 1250 km2 and reaches an altitude of about 3340 m. It has been persistently active during historical time, with frequent paroxysmal episodes separated by passive degassing periods. Atmospheric precipitation was collected approximately every two weeks, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of Etna Volcano. The collected samples were analysed for major (Ca, Mg, K, Na, F, SO4, Cl, NO3) and a large suite of trace elements (Ag, Al, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Si, Sb, Sc, Se, Sr, Th, Ti, Tl, U, V, Zn) by using different techniques (IC, SPEC, ICP-MS and CV-AFS). The monitoring of atmospheric deposition gave the opportunity to occasionally sample volcanic fresh ashes emitted by the volcano during the paroxysmal events. This was possible because the network of five rain gauges were equipped with a filter-system to block the coarse material. In this way, more than twenty events of ashfall were collected. Unfortunately, only half of these samples were suitable for a complete chemical analysis, because of the small amount of sample. In order to obtain elemental chemical composition of ashes, powdered samples were analysed by a combination of methods, including X-ray Fluorescence Spectroscopy (XRF), total digestion followed by Inductively Coupled Plasma Emission Mass Spectrometry (ICP-MS), Instrumental Neutron Activation Analysis (INAA), and infrared detection (IR). The chemistry of rainwater reveals that most of the investigated elements have higher concentrations close to the emission vent of the volcano, confirming the prevailing volcanic contribution. Rainwater composition clearly reflects the volcanic plume input. Ash-normalised rainwater composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/ash concentration ratios. The degree of interaction between collected ash and rainwater was variable, depending on several factors: (i) the length of the period in which tephra was present in the sampler (the ash fall may have occurred any day from the first to the last day of the rain collecting period); (ii) the amount of rainwater fallen on the collectors after the ash-fall event, and its acidity; (iii) the granulometry of the ash samples that was widely variable (from few centimetres to micrometric particles) increasing the interaction with decreasing dimensions of the grains; (iv) the distance of collector with respect to the craters. In order to investigate the role of volcanic ash on the evolution of the rainwater chemistry, absolute concentrations of rain and ash were plotted in binary plot diagrams (Figure 1). Each diagram corresponds to a single event, and pH and TDS of the solution collected is reported. The diagonal bars in the diagrams represent the rain/ash ratios (1:1 and 1:10000). The results confirm that sulphate and halide salt aerosols are adsorbed onto ash particles, and their rate of dissolution in rainwater depends on solubility. Moreover, rapid chemical weathering of the silicate glass by volcanic acid (SO2, HCl and HF) can also explain the enrichment of several refractory elements (Na, K, Ca, Mg, Si, Al, Fe, Ti, Sc). Our observations highlight how explosive activity can increase enormously the deposition rate of several chemical elements, up to several km away from the emission vents.

Beschreibung: Published

Beschreibung: Nicolosi (Catania)

Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Beschreibung: open

Beschreibung: This paper describes the status of the Italian National Seismic Network and the main feautures of the Italian seismicity in 2010. In that year the network counted 313 velocimeters and 107 accelerometers. More than 14500 earthquakes were located in Italy and surrounding areas and seas, with an average minimum magnitude of completeness MC = 1.6. Most of that seismicity appears in cluster (a spatio-temporal concentration of seismic events): in 2010 more than 70% of the located Italian earthquakes belongs to about 430 cluster. We selected all the cluster with at least 20 events of any magnitudes, and all the cluster with at least 10 events and at least one event of magnitude 2.5 or greater, and cluster with at least two events and one of magnitude 3.5 or greater, ending up with a list of 48 significant cluster. The Italian Seismic Bulletin contains also seismic events originated by anthropic activities (quarry explosions). Through the analysis of the last 7 years of data from the bulletin, we pinpointed 16 areas with extended extractive activities. Nevertheless the presence of quarries in Italy is so widespread that our list can be considered by no means complete. Extraction areas frequently coincide with regions affected by high seismicity rate. Records due to explosion quakes can show distinguishing characteristics (compressive first onset and a low frequency secondary phase). However, these markers are not present in all the artificial events, and are not sufficient to exclude the totality of the explosions from the bulletin. Nowadays the BSI incorporates, together with true tectonic earthquakes, a significant portion of low magnitude events due to explosions, evaluated about 5% in 2010.

Beschreibung: Published

Beschreibung: 1-52

Beschreibung: 5.2. TTC - Banche dati di sismologia strumentale

Beschreibung: N/A or not JCR

Beschreibung: open

Beschreibung: A seismic noise recording experiment has been carried out in the Campi Flegrei volcanic area from March 9 to 26, 2009 in the framework of the INGV-DPC 2007-2009 agreement (Project V1 – UNREST). The project aimed at the realization of an integrated method for the definition of the unrest phases at Campi Flegrei. 21 digital three-component seismic stations equipped with broad band seismometers have been added to the existing 11 digital stations already deployed in the area. The preliminary results show a correlation between the seismic noise level and the anthropic activity, whereas the meteorological conditions seem affecting the low frequency seismic noise. These results are important to define the detection thresholds of the seismic signals generated during a possible renewal phase of the volcanic activity.

Beschreibung: Published

Beschreibung: 1-21

Beschreibung: N/A or not JCR

Beschreibung: open