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04. Solid Earth
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- PublicationOpen AccessGeoelectrical investigation for the assessment of groundwater conditions: a case study(2005-12)
; ; ;Lashkaripour, G. R.; Department of Geology, University of Sistan and Baluchestan, Zahedan, Iran ;Nakhaei, M.; Department of Geology, University of Tarbiat Moallem, Tehran, Iran; An electrical resistivity survey involving Vertical Electrical Soundings (VES) was carried out in the Shooro Basin in Southeast Iran in order to study groundwater conditions such as depth, thickness and aquifer boundaries. Vertical electrical soundings by Schlumberger array were conducted in this area. The resistivity Schlumberger soundings which have a maximum current electrode spacing (AB) ranging from 200 m to 600 m were carried out at 207 positions in 19 profiles. Interpretation of these soundings indicates the presence of an alluvial aquifer. This aquifer is divided into eastern and western parts by the Shooro River, which comprises a variable thickness and resistivity of deposits. The average permeability coefficient and resistivity in the western part, especially southwest is higher than the eastern part of the aquifer. Therefore, it seems that Shooro River follows a fault zone in the region. The high resistivity of west part is due to the water quality and the existence of alluvial fan with coarse grain materials. Low aquifer resistivities in the east are associated with finer materials and also brackish water infiltration from the adjacent basin mainly in the central part of the aquifer. Furthermore, zones with high yield potential have been determined in this research based on the resistivity data. - PublicationOpen AccessEvidence for a geomagnetic jerk in 1990 across Europe(1995-09)
; ; ;Cafarella, L.; Istituto Nazionale di Geofisica, Roma, Italy ;Meloni, A.; Istituto Nazionale di Geofisica, Roma, Italy; The analysis of geomagnetic data from magnetic observatories demonstrated the existence of very rapid changes, or jerks, in the secular variation, especially the occurrence of the well known geomagnetic jerks of 1969 and 1978. A new geomagnetic jerk seems to have appeared around 1990 and is clearly visible at a selec- tion of European magnetic observatories as a rapid and sudden change in the secular variation pattern. The comparison between all day and quiet day means for two different observatories, respectively at high and middle latitude, suggests that this phenomenon, as stated by many authors for the other jerks, could be generated by an internal source. - PublicationRestrictedLong-term multi-hazard assessment for El Misti volcano (Peru)(2014)
; ; ; ; ; ;Sandri, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Thouret, J.; PRES Clermont, Université Blaise Pascal, Laboratoire Magmas et Volcans ;Constantinescu, R.; Faculty of Geography, Babeş-Bolyai University ;Biass, S.; Section des sciences de la Terre et de l’environnement, Université de Genève ;Tonini, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; ; ; We propose a long-term probabilistic multi-hazard assessment for El Misti Volcano, a composite cone located <20 km from Arequipa. The second largest Peruvian city is a rapidly expanding economic centre and is classified by UNESCO as World Heritage. We apply the Bayesian Event Tree code for Volcanic Hazard (BET_VH) to produce probabi- listic hazard maps for the predominant volcanic phenomena that may affect c.900,000 people living around the volcano. The methodology accounts for the natural variability displayed by volcanoes in their eruptive behaviour, such as different types/sizes of eruptions and possible vent locations. For this purpose, we treat probabilistically several model runs for some of the main hazardous phenomena (lahars, pyroclastic density currents (PDCs), tephra fall and ballistic ejecta) and data from past eruptions at El Misti (tephra fall, PDCs and lahars) and at other volcanoes (PDCs). The hazard maps, although neglecting possible interactions among phenomena or cascade effects, have been produced with a homogeneous method and refer to a common time window of 1 year. The probability maps reveal that only the north and east suburbs of Arequipa are exposed to all volcanic threats except for ballistic ejecta, which are limited to the uninhabited but touristic summit cone. The probability for pyroclastic density currents reaching recently expanding urban areas and the city along ravines is around 0.05 %/year, similar to the probability obtained for roof-critical tephra load- ing during the rainy season. Lahars represent by far the most probable threat (around 10 %/year) because at least four radial drainage channels can convey them approximately 20 km away from the volcano across the entire city area in heavy rain episodes, even without eruption. The Río Chili Valley repre- sents the major concern to city safety owing to the probable cascading effect of combined threats: PDCs and rockslides, dammed lake break-outs and subsequent lahars or floods. Although this study does not intend to replace the current El Misti hazard map, the quantitative results of this probabilistic multi-hazard assessment can be incorporated into a multi-risk analysis, to support decision makers in any future improvement of the current hazard evaluation, such as further land-use planning and possible emergency management.353 64 - PublicationRestrictedA paleoclimate record with tephrochronological age control for the last glacial-interglacial cycle from Lake Ohrid, Albania and Macedonia(2010)
; ; ; ;Vogel, H.; Institute of Geology and Mineralogy, University of Cologne, Köln, Germany ;Wagner, B.; Institute of Geology and Mineralogy, University of Cologne, Köln, Germany ;Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; ; Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study climatic and environmental changes during the last glacial-interglacial cycle are reconstructed using lithological, sedimentological, geochemical and physical proxy analysis of a 15-m-long sediment succession from Lake Ohrid. A chronological framework is derived from tephrochronology and radiocarbon dating, which yields a basal age of ca. 136 ka. The succession is not continuous, however, with a hiatus between ca. 97.6 and 81.7 ka. Sediment accumulation in course of the last climatic cycle is controlled by the complex interaction of a variety of climate-controlled parameters and their impact on catchment dynamics, limnology, and hydrology of the lake. Warm interglacial and cold glacial climate conditions can be clearly distinguished from organic matter, calcite, clastic detritus and lithostratigraphic data. During interglacial periods, short-term fluctuations are recorded by abrupt variations in organic matter and calcite content, indicating climatically-induced changes in lake productivity and hydrology. During glacial periods, high variability in the contents of coarse silt to fine sand sized clastic matter is probably a function of climatically-induced changes in catchment dynamics and wind activity. In some instances tephra layers provide potential stratigraphic markers for short-lived climate perturbations. Given their widespread distribution in sites across the region, tephra analysis has the potential to provide insight into variation in the impact of climate and environmental change across the Mediterranean.123 26 - PublicationRestrictedEvaluation of carbon isotope fractionation of soil CO2 under an advective–diffusive regimen: A tool for computing the isotopic composition of unfractionated deep source(2007-06-15)
; ; ; ; ;Camarda, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;De Gregorio, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Favara, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Gurrieri, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; A physical model based on the advective–diffusion theory was developed in order to describe the mixing between a deep gas source and the atmosphere. The model was used to predict the isotopic fractionation of carbon in soil CO2. Gas samples were collected at different depths in areas characterized by different geological settings and CO2 fluxes. The relative theoretical and experimental isotopic profiles were compared and a good agreement was found. These profiles show how the isotopic composition of CO2 changes through the upper few decimeters of soil and how the amount of the isotopic fractionation is strongly influenced by soil CO2 flux. Finally, the model was used to derive the carbon isotopic composition of unfractioned deep CO2 source for all the investigated sites365 40 - PublicationRestrictedThe Averno 2 fissure eruption: a recent small-size explosive event at the Campi Flegrei Caldera (Italy)(2011)
; ; ; ; ; ; ; ;Di Vito, M. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Arienzo, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Braia, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Civetta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;D’Antonio, M.; Università di Napoli ;Di Renzo, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Orsi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ;; ; ; The Averno 2 eruption (3,700 ± 50 a B.P.) was an explosive low-magnitude event characterized by magmatic and phreatomagmatic explosions, generating mainly fall and surge beds, respectively. It occurred in the Western sector of the Campi Flegrei caldera (Campanian Region, South Italy) at the intersection of two active fault systems, oriented NE and NW. The morphologically complex crater area, largely filled by the Averno lake, resulted from vent activation and migration along the NE-trending fault system. The eruption generated a complex sequence of pyroclastic deposits, including pumice fall deposits in the lower portion, and prevailing surge beds in the intermediate-upper portion. The pyroclastic sequence has been studied through stratigraphical, morphostructural and petrological investigations, and sub- divided into three members named A through C. Member A was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km. During this phase the eruption reached its climax with a mass discharge rate of 3.2 106 kg/s. Intense fracturing and fault activation favored entry of a significant amount of water into the system, which produced explosions driven by variably efficient water-magma inter- action. These explosions generated wet to dry surge deposits that emplaced Member B and C, respectively. Isopachs and isopleths maps, as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a NE oriented, 2 km long fissure. The total volume of magma extruded during the eruption has been estimated at about 0.07 km3 (DRE). The erupted products range in composition from initial, weakly peralkaline alkali-trachyte, to last-emplaced alkali-trachyte. Isotopic data and modeling suggest that mixing occurred during the Averno 2 eruption between a more evolved, less radiogenic stored magma, and a less206 18 - PublicationOpen AccessAmbient vibration analysis as a proxy for the detection of buried geological structures(2016)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In this work we tested the capability of single station ambient noise spectral ratios (HVNSR) technique to be used as a proxy for detecting sharp variations in the subsoil characteristics in sedimentary basins. In sites characterized by 1D response HVNSR is able to detect the resonance frequency of sediments (f0) to be related with their thickness and velocity. In quasi-1D geological situation, a smooth variation in the resonance frequency suggests some variation in the thickness of the soft sedimentary layers or in their velocity. In the case of sharp lateral variation of the subsoil, as in presence of morphological steps or buried faults in the bedrock, the noise wave-field becomes more complex and spectral ratios show some directional effect strictly related to the presence of the lateral heterogeneity (Matsushima et al. 2014). In this work we focus our attention on the detection of a buried shallow tectonic element known in bibliography (Galadini, Galli 1999) as the Luco dei Marsi fault, located in the western margin of the Fucino basin (central Appenines, Italy). We performed simultaneous ambient noise measurements using MarsLite digitizers equipped with Lennarts 3d-5s velocimeters along a transect, with inter-station distance between 30 and 50 meters, which crosses perpendicularly the surface projection of fault line. The collected data, analyzed with classical HVNSR technique, show some complexities in the f0 distribution compatible with the presence of the buried fault. In detail, our results highlight a 1D response with a clear resonance peak for the stations located away from the fault. Moving closer to the fault line, where the 1D condition is not verified, the resonance peak becomes broader. Directional analysis of spectral ratios suggests the dependence of the noise wave-field to the presence of the fault line. Close to the geological feature, results of directional analysis show a doubling in the resonance frequency with relative amplitudes changing for fault-parallel and fault-normal direction of polarization. To support with an independent approach our observations, an electrical resistivity tomography was performed along the transect whose results show the presence of a clear step in a high resistivity shallow layer that can be assumed as the bedrock. After this analysis we decided to extend the ambient noise transect towards the centre of the basin where no fault line is mapped and where we expected a smooth lowering of f0 values due to the deepening of the bedrock. This feature was really observed for a while but at a distance between 400 and 500 meters from the Luco fault we detected again some anomaly in HVNSR data with a doubling of resonance frequency and relative amplitudes depending from the direction of polarization. This observation suggests the presence of deeper tectonic element parallel to the Luco fault. As a conclusion of our work we believe that HVNSR and polarization analysis can represent a quick and fast method to hypothesize the presence of buried discontinuity in the subsoil and can be usefully used to guide the positioning of more sophisticated geophysical analysis aimed at mapping their geometries.78 13 - PublicationOpen AccessImplementazione di una nuova procedura per caratterizzare la forma di particelle mediante misure al CAMSIZER e algoritmi di clustering(2011)
; ; ; ; ; ;Lo Castro, M. D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cassisi, C.; Università degli Studi di Catania ;Montalto, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Prestifilippo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; In this work we present the calibration phase of a new procedure for the characterization of the shape of pyroclastic particles. This research has been granted by INGV of Catania, with funds deriving from the “Progetto Giovani”, in collaboration with Retsch Technology in Haan. The innovation of this procedure arises from the use of CAMSIZER (an instrument developed by the German leader company). This instrument permits to obtain very important information both on size and shape parameters of a high number of particles (hundreds of thousands data). Moreover, we used clustering and classification algorithms in order to group particles according to their morphologic characteristics. This calibration phase has been tested only on standard materials with regular geometries such as cubes, spheres and cylinders. In the future we will apply this methodology to volcanic ash particles that, as well-known, are characterized by irregular morphologies.593 445 - PublicationOpen AccessStefano Breventano, Trattato del Terremoto(2007-11)
; ;Albini, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, ItaliaIl 16 novembre 1570 un terremoto colpisce Ferrara ed il pavese Stefano Breventano decide di scrivere un Trattato del Terremoto. Un trattato mai pubblicato e conservato manoscritto presso la Biblioteca Ambrosiana di Milano, che viene qui proposto in una edizione critica curata da Paola Albini. In realtà, il vero trattato è contenuto integralmente nel primo dei sette libri che compongono il manoscritto e per quanto assai pochi dei concetti ivi espressi possano essere oggi condivisi, colpisce la razionalità della sequenza degli argomenti trattati, che potrebbero costituire l’indice dei contenuti di un manuale di sismologia applicata di oggi. Dal libro secondo il manoscritto diventa una sorta di storia universale, scandita da terremoti, inondazioni, pestilenze, incendi e fenomeni strani.324 864 - PublicationRestrictedThe Gravimetric Station of Brasimone: results of an intercomparison experiment between gravimeters(2000)
; ; ; ; ;Casula, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Baldi, P.; Dipartimento di Fisica - Settore Geofisica - Università di Bologna - Italy ;Hinderer, J.; Istitut de Physique du Globe, Strasbourg, France ;Amalvict, M.; Istitut de Physique du Globe, Strasbourg, France; ; ; The GWR Superconducting Gravimeter (T015) is working continuously in a laboratory of the Research Center of ENEA (Italian National Institute for Energy Development)since 1995 in the frame of Global Geodynamics Project. The data are periodically send to the ICET to be analysed and to produce a valuable tool of high precision monitoring of the global gravity field. The superconducting gravimeter is periodically calibrated by means of a moving mass system with a precision better than 0.3%. In October 1997 a campaign involving the FG5-206 of the Institut de Physique du Globe of Strasbourg was performed in order to verify and to improve the calibration constant of the superconducting gravimeter (SC). The SC calibration constant was computed with the help of absolute gravity and with the mass system. In spite of the large amount of seismic noise present in the data, a good agreement between the two methods, at the 0.1% level, was obtained, improving the calibration factor of the SC gravimeter by a factor of three.156 28