http://hdl.handle.net/2122/260 Mon, 20 May 2013 22:47:23 GMT 2013-05-20T22:47:23Z http://hdl.handle.net/2122/8697 Title: Sulphur-gas concentrations in volcanic and geothermal areas in Italy and Greece: Characterising potential human exposures and risks Authors: D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Aiuppa, A.; Università di Palermo, Dipartimento DiSTeM; Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Calabrese, S.; Università di Palermo, Dipartimento DiSTeM; Kyriakopoulos, K.; University of Athens, Dept. Geology and Geoenvironment, Greece; Liotta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Longo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: Passive samplers were used to measure the atmospheric concentrations of SO2 naturally emitted at three volcanoes in Italy (Etna, Vulcano and Stromboli) and of H2S naturally emitted at three volcanic/geothermal areas in Greece (Milos, Santorini and Nisyros). The measured concentrations and dispersion patterns varied with the strength of the source (open conduits or fumaroles), the meteorological conditions and the area topography. At Etna, Vulcano and Stromboli, SO2 concentrations reach values that are dangerous to people affected by bronchial asthma or lung diseases (>1000 μg m−3). H2S values measured at Nisyros also exceed the limit considered safe for the same group of people (>3000 μg m−3). The data obtained using passive samplers represent time-averaged values over periods from a few days up to 1 month, and hence concentrations probably reached much higher peak values that were potentially also dangerous to healthy people. The present study provides evidence of a peculiar volcanic risk associated with tourist exploitation of active volcanic areas. This risk is particularly high at Mt. Etna, where the elderly and people in less-than-perfect health can easily reach areas with dangerous SO2 concentrations via a cableway and off-road vehicles Wed, 31 Jul 2013 22:00:00 GMT http://hdl.handle.net/2122/8697 2013-07-31T22:00:00Z http://hdl.handle.net/2122/8696 Title: The 4D imaging of the source of ground deformation at Campi Flegrei caldera (southern Italy) Authors: D'Auria, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Giudicepietro, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Martini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Lanari, R.; Istituto per il Rilevamento Elettromagnetico dell’Ambiente, Consiglio Abstract: We have applied a tomographic imaging technique to the inversion of a DInSAR data set at Campi Flegrei caldera. This technique allowed us to determine the temporal and spatial distribution of volumetric strain sources up to 5 km depth. Results have shown complex spatial and temporal patterns, identifying important features that were not noticed before. The first result is the observation of positive strain sources (expansion) migrating upward (in 2000 and 2006). We have interpreted them as hot fluid batches injected at the bottom of the geothermal reservoir, migrating upward and reaching the surface. Furthermore we have identified an injection episode (in 1997), which was not recognized before. This batch did not reach the surface and probably dissipated by diffusion and lateral advection without producing significant ground uplift. The injection of fluid batches does not occur at the center of the caldera, but along its borders. The three identified injection episodes (in 1997, 2000 and 2006) occur in different points. In 2000 and 2006, the injected fluids migrated, subsequently, toward the center of the caldera. Our findings agrees with results of other geophysical and geochemical studies. These results suggest a new framework for the modeling of Campi Flegrei geothermal system and for the interpretation of data recorded by the multiparametric monitoring networks on the caldera. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8696 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8692 Title: Waveform Variation of the Explosion-Quakes as a function of the eruptive activity at Stromboli Volcano Authors: Esposito, A. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; D'Auria, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Giudicepietro, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Martini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Editors: Apolloni, B.; Bassis, S.; Esposito, A.; Morabito, F.C. Abstract: In the period from June to September 2011, the Stromboli volcano was affected by an activity characterized by an increase of the volcanic tremor amplitude, in the magnitude of explosions and with some lava overflows. In order to examine and understand in more detail this particular phase of the volcano, we present here an unsupervised investigation of the waveform variation of the explosion-quakes recorded during this period. The aim is to identify a possible relationship between the temporal changes of these events and the volcano seismic activity. The analysis is performed on a dataset of about 8400 explosion-quakes by using a SOM neural network. This technique works well with large datasets allowing to find out unpredicted characteristics among them. The SOM clustering highlights sudden changes occurring at the end of July and of August and a permanent variation between June and September reflecting a modification in the volcano activity. These results could be interesting for focusing the analysis of the seismological dataset in these intervals in order to evidence minor, but important variations, which were previously undetected and to improve the knowledge on the explosive dynamics of the volcano. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8692 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8691 Title: Intersection of exogenous, endogenous and anthropogenic factors in the Holocene landscape: A study of the Naples coastline during the last 6000 years Authors: Romano, P.; Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, Largo S. Marcellino 10, 80138 Naples, Italy; Di Vito, M. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Giampaola, D.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Cinque, A.; Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, Largo S. Marcellino 10, 80138 Naples, Italy; Bartoli, C.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Boenzi, G.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Detta, F.; Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, Largo S. Marcellino 10, 80138 Naples, Italy; Di Marco, M.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Giglio, M.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Iodice, S.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy; Liuzza, V.; Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, Largo S. Marcellino 10, 80138 Naples, Italy; Ruello, M. R.; Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università di Napoli Federico II, Largo S. Marcellino 10, 80138 Naples, Italy; Schiano di Cola, C.; Soprintendenza Speciale ai Beni Archeologici di Napoli e Pompei, Museo Archeologico Nazionale, Naples, Italy Abstract: New data on the ancient landscape of Naples (southern Italy) during the middle and late Holocene from geo-archaeological excavations associated with public transport works were used to reconstruct the hill and coastal environment to the west of the ancient Graeco-Roman polis, where remains of human settlements date to the late Neolithic. The rich stratigraphic and archaeological records that emerged from the digs and from previous boreholes were measured and analysed by combining sedimentary facies analysis, tephrostratigraphy and archaeological data. Between the 5th and 4th millennia BP, a rocky profile with a wave-cut platform cutting across pyroclastites emplaced from the surrounding volcanoes was predominant in the coastal landscape. During the 3rd millennium BP, this rocky coast was progressively replaced by a sandy littoral environment primarily due to marine deposition, with a coastline located some hundred meters inland with respect to the modern one. The sedimentary record of the Greek and Roman periods indicates short-term fluctuations of the coastline, leading to the establishment of a backshore environment towards the end of the 6th century AD, when prograding river mouths and lobes of debris flows contributed to the advancing trend of the shoreline. The frequent archaeological remains from these periods indicate a stable settled area since Roman times. The shoreline was still subject to short-lived fluctuations between the 12th and 16th centuries, and attained its present position during the modern era with man-made reshaping of its profile. The construction of Relative Sea Level curves for two coastal sites reveals that the persistence of the foreshore environment in the Naples coastal strip during the 5th and 4th millennia BP was controlled by the counterbalancing effect of either the concurrent eustatic sea level rise or subsidence. On the other hand, the morpho-stratigraphic record for the last two millennia shows a significant correlation between sedimentation rate and settlement history, accounting for the dominant role of the anthropogenic forcing-factor in late Holocene landscape history. In particular, land mismanagement during Late Antiquity seems to have triggered a slope disequilibrium phase, exacerbating soil erosion and increasing the sediment accumulation rate in both foothill and coastal areas. Nonetheless, the environmental changes of the Chiaia coast during the last 2000 years clearly show volcanicetectonic perturbations influencing coastline development up to the modern era. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8691 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8689 Title: Automatic recognition of landslide seismic signals based on neural network analysis of seismic signals: an application to the monitoring of Stromboli volcano (Southern Italy) Authors: Esposito, A. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; D'Auria, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Giudicepietro, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Peluso, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Martini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: In the last 9 years, the amount and the quality of geophysical and volcanological observations of Stromboli's' activity have undergone a marked increase. This new information highlighted that the landslides on the Sciara del Fuoco flank are tightly linked to the volcanic activity. Actually, at the beginning of the December 28, 2002, effusive eruption, the seismic monitoring network was less dense than now, and therefore it is not known if there was an increase in the landslide rate before the eruption. Despite this, it is known that a big landslide occurred 2 days after the beginning of the eruption which caused a tsunami (December 30, 2002). More recently, the effusive eruption in February 2007 was preceded by an increase in landslides on the Sciara del Fuoco flank, which were recorded by the seismological monitoring system that had been improved after the 2002–2003 crisis. These episodes led us to believe that monitoring the Sciara del Fuoco flank instability is an important topic, and that landslides might be significant short-term precursors of effusive eruptions at the Stromboli volcano. To automatically detect landslide signals, we have developed a specialized neural algorithm. This can distinguish between landslides and the other types of seismic signals usually recorded at the Stromboli volcano (i.e., explosion quakes and volcanic tremor). The discrimination results show an average performance of 98.67 %. According to the experience of the crisis of 2007, to identify changes that can be considered as precursors of effusive eruptions, we set up an automatic decision-making method based on the neural network responses. This method can operate on a continuous data stream. It calculates a landslide percentage index (LPI) that depends on the number of records that are classified by the net as landslides over a given time interval. We tested the method on February 27, 2007, including the beginning of the effusive phase. The index showed an increase as early as at 09:00 UTC on that day and reached its maximum value (100 %) at 12:00, about 40 min before the onset of the eruption. After the beginning of the effusive phase, the index remains high due to the blocks that roll down along the slope from the front of the lava flow. On the basis of these tests, we propose a decision-making method that is able to recognize a trend in the LPI similar to that of 2007 eruption, allowing the identification of precursors of effusive phases at the Stromboli volcano. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8689 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8687 Title: Automatic analysis of seismic data by using Neural Networks: applications to Italian volcanoes Authors: Giudicepietro, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Esposito, A; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; D'Auria, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Martini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Scarpetta, S.; Università di Salerno Editors: Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Zollo, A.; Università di Napoli Federico II Abstract: The availability of the new computing techniques allows to perform advanced analysis in near real time, improving the seismological monitoring systems, which can extract more significant information from the raw data in a really short time. However, the correct identification of the events remains a critical aspect for the reliability of near real time automatic analysis. We approach this problem by using Neural Networks (NN) for discriminating among the seismic signals recorded in the Neapolitan volcanic area (Vesuvius, Phlegraean Fields). The proposed neural techniques have been also applied to other sets of seismic data recorded in Stromboli volcano. The obtained results are very encouraging, giving 100% of correct classification for some transient signals recorded at Vesuvius and allowing the clustering of the large dataset of VLP events recorded at Stromboli volcano. Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2122/8687 2007-12-31T23:00:00Z http://hdl.handle.net/2122/8685 Title: Studio di fattibilità per il monitoraggio delle deformazioni del fondo marino tramite GPS su una meda elastica (Golfo di Pozzuoli – Campi Flegrei) Authors: De Martino, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Guardato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Tammaro, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Iannaccone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: The continuous measurement of ground deformations is an important contribution to the monitoring of volcanic areas. When the volcano is totally or partially submerged, the traditional geodetic methods cannot be applied and the measures of seafloor deformation are extremely difficult and expensive. This paper describes the installation of a continuous GPS station on an elastic beacon. The measurements were conducted in the Campi Flegrei Caldera (Gulf of Pozzuoli, Naples), whose vertical displacements are related to the bradyseismic phenomenon. Experimental observations show that it’s possible to monitor vertical displacement of seafloor with a resolution of a few centimeters, also taking into account for measurement errors (due to weather and sea conditions acting on the elastic beacon). This non expensive technique is relevant at Campi Flegrei area, because it extends the ground deformation monitoring at sea, contributing to a better modeling of the deformation field. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8685 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8669 Title: Curie isotherm depth from aeromagnetic data constraining shallow heat source depths in the central Aeolian Ridge (Southern Tyrrhenian Sea, Italy) Authors: De Ritis, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Ravat, D.; Department of Earth and Environmental Sciences, University of Kentucky; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The Salina, Lipari, and Vulcano volcanic ridge and the surrounding sea sectors (Aeolian Archipelago, Southern Tyrrhenian Sea, Italy) are characterized by vents responsible for a recent (<40 ka—1889/1890 AD) effusive and explosive subareal activity and repeated, 56 to 7 ka in age, submarine explosive eruptions from source areas located between Lipari and Vulcano. A spectral depth estimation of the magnetic bottom using a fractal method on aeromagnetic data from Vulcano, Lipari, and Salina volcanic ridge allows us to constrain the Curie isotherm depth. The elevated portion of the isotherm is between 2 and 3 km below Salina and Vulcano and about 1 km below Lipari. The Curie depth results in the context of other geological and geophysical evidence suggest that the rise of the Curie isotherm is mainly due to the occurrence of shallow heat sources such as magma ponds and associated hydrothermal systems. The short-wavelength magnetic anomaly field reflects magnetic contrasts from highly magnetized volcanic bodies, low-magnetization sediments, and hydrothermally altered rocks. Borehole temperature data verify the Curie temperature derived from the magnetic methods on the island of Vulcano.We conclude that the whole Vulcano, Lipari, and Salina volcanic ridge is active and should be monitored. Tue, 19 Mar 2013 23:00:00 GMT http://hdl.handle.net/2122/8669 2013-03-19T23:00:00Z http://hdl.handle.net/2122/8667 Title: Terrain characterization and structural control of the Auca Mahuida volcanism (Neuquén Basin, Argentina) Authors: Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; De Ritis, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Longo, M.; Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, La Plata, Argentina; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Geomorphometric parameters (slope, aspect, valley depth, and areal density of cones) derived from a moderate resolution digital elevation model with a grid spacing of 100 m are used in an attempt to interpret the tectonic/structural features related to surface deformation in the Auca Mahuida volcanic terrain (Neuquén Basin, Argentina). The Auca Mahuida (2.03–0.88 Ma) is the southernmost volcanic field of the Payenia volcanic province, in the Andean foreland. The foreland is subjected to an E–W compression related to the eastward migration of the N–S striking thrust front of the Andes. The geomorphometric analysis indicates that the Auca Mahuida consists of a basal, E–W elongated lava field with monogenic vents and a summit, polygenic, also E–W elongated, cone. A N100◦E striking fault controls the southern flank of the field, which is also affected by scarps related to erosional and gravity-controlled processes. The drainage network shows a pseudo-radial pattern around the summit cone, and the Auca Mahuida’s deepest valley is structurally controlled by a NNW–SSE striking fault affecting the sedimentary basement. The volcanic field lies on a NE to E dipping substratum. The areal distribution of the monogenic cones is consistent with ascent of magmas along E–W striking fractures, and with elastic models of a pressurized hole (magma chamber) subjected to an E–W compression. At Auca Mahuida, the ascent of melts from the mantle is controlled, in the overriding crust, by tectonic structures formed in response to the E–W compression of the Andes. Wed, 31 Oct 2012 23:00:00 GMT http://hdl.handle.net/2122/8667 2012-10-31T23:00:00Z http://hdl.handle.net/2122/8654 Title: A second order accurate numerical model for multiphase underexpanded volcanic jets Authors: Carcano, S.; MOX – Modelling and Scientific Computing, Dipartimento di Matematica F. Brioschi, Politecnico di Milano, Milano, Italy; Bonaventura, L.; MOX – Modelling and Scientific Computing, Dipartimento di Matematica F. Brioschi, Politecnico di Milano, Milano, Italy; Neri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Esposti Ongaro, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia Abstract: An improved version of the PDAC (Pyroclastic Dispersal Analysis Code) numerical model for the simulation of multiphase volcanic flows is presented and validated for the simulation of multiphase volcanic jets in supersonic regimes. The present version of PDAC includes second-order time and space discretizations and fully multidimensional advection discretizations, in order to reduce numerical diffusion and enhance the accuracy of the original model. The resulting numerical model is tested against the problem of jet decompression in both two and three dimensions. For homogeneous jets, numerical results show a good quantitative agreement with experimental results on the laboratory scale in terms of Mach disk location (Lewis and Carlson, 1964). For multiphase jets, we consider monodisperse and polydisperse mixtures of particles with different diameter. For fine particles, for which the pseudogas limit is valid, the multiphase model correctly reproduces predictions of the pseudogas model. We obtain that particles are in mechanical and thermal equilibrium with the gas phase and the jet decompression structure is in quantitative agreement with pseudogas results (Ogden et al., 2008b). For both fine and coarse particles, we measure the importance of multiphase effects with relation to the characteristic time scales of multiphase jets and we quantify how particles affect the average jet dynamics in terms of pressure, mixture density, vertical velocity and temperature. Furthermore, time dependent vent conditions are introduced, in order to achieve numerical simulation of eruption regimes characterized by transient jet behaviour. We show how in case of rapid change in vent conditions, volcanic jet structures do not evolve through a succession of steady state configurations and the transition between different flow conditions can result in the collapse of the volcanic column. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8654 2011-12-31T23:00:00Z