http://hdl.handle.net/2122/268 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/6062 Titolo: The source of infrasound associated with long-period events at Mount<br/><br/>Autori: Matoza, R. S.; Laboratory for Atmospheric Acoustics, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California; Garcés, M. A.; Infrasound Laboratory, Hawai’i Institute of Geophysics andPlanetology, University of Hawai’i at Manoa; Chouet, B. A.; U.S. Geological Survey, Menlo Park, California; D' Auria, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Hedlin, M. A. H.; Laboratory for Atmospheric Acoustics, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California; De Groot-Hedlin, E.; Laboratory for Atmospheric Acoustics, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California; Waite, G. P.; U.S. Geological Survey, Menlo Park, California<br/><br/>Abstract: During the early stages of the 2004–2008 Mount St. Helens eruption, the sourceprocess that produced a sustained sequence of repetitive long-period (LP) seismic eventsalso produced impulsive broadband infrasonic signals in the atmosphere. To assesswhether the signals could be generated simply by seismic-acoustic coupling from theshallow LP events, we perform finite difference simulation of the seismo-acousticwavefield using a single numerical scheme for the elastic ground and atmosphere. Theeffects of topography, velocity structure, wind, and source configuration are considered.The simulations show that a shallow source buried in a homogeneous elastic solidproduces a complex wave train in the atmosphere consisting of P/SV and Rayleigh waveenergy converted locally along the propagation path, and acoustic energy originating fromthe source epicenter. Although the horizontal acoustic velocity of the latter isconsistent with our data, the modeled amplitude ratios of pressure to vertical seismicvelocity are too low in comparison with observations, and the characteristic differences inseismic and acoustic waveforms and spectra cannot be reproduced from a commonpoint source. The observations therefore require a more complex source process in whichthe infrasonic signals are a record of only the broadband pressure excitation mechanism ofthe seismic LP events. The observations and numerical results can be explained by amodel involving the repeated rapid pressure loss from a hydrothermal crack by ventinginto a shallow layer of loosely consolidated, highly permeable material. Heating bymagmatic activity causes pressure to rise, periodically reaching the pressure threshold forrupture of the ‘‘valve’’ sealing the crack. Sudden opening of the valve generates thebroadband infrasonic signal and simultaneously triggers the collapse of the crack,initiating resonance of the remaining fluid. Subtle waveform and amplitude variability ofthe infrasonic signals as recorded at an array 13.4 km to the NW of the volcano areattributed primarily to atmospheric boundary layer propagation effects, superimposedupon amplitude changes at the source. http://hdl.handle.net/2122/6058 Titolo: SeismNet Manager: A Web Application to Manage Hardware and Data of a Seismic Network<br/><br/>Autori: Elia, L.; AMRA Scarl; Satriano, C.; AMRA Scarl; Iannaccone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Modern seismic networks have grown to become increasinglycomplex infrastructures, composed of hundreds of devices anddata streams scattered over wide geographic regions. Amongthe components of such networks are heterogeneous seismicand environmental sensors, digitizers, data loggers, data collectionservers, wired and wireless communication hardware,and other devices and software subsystems charged with differentdata handling tasks, such as continuous data storage oranalysis. In order to be effectively managed, a seismic networktherefore needs a tiered software application. This applicationencompasses tasks that range from the low-level (hardwaremonitoring for failure detection) to the mid-level (data qualitycontrol) to the high-level (managing the final output of thenetwork: recorded events, waveforms, and parametric data). Atthe same time such an application should provide a centralizedand easy-to-use graphical user interface (GUI).Over the past two decades, several institutions and commercialcompanies have devoted great efforts to the developmentof software tools to manage and centralize the dataacquisition and analysis for regional to global seismic networks.Among the most valuable products worth mentioningare: Earthworm, an open-source real-time seismic managementsystem developed by the U.S. Geological Survey (Johnson etal. 1995); Antelope, a commercial real-time system for environmentaldata collection, developed by Boulder Real TimeTechnologies (BRTT 2008); and the more recent SeisComP(Hanka et al. 2000), an open-source tool for real-time dataacquisition and analysis developed by the German ResearchCentre for Geosciences (GFZ-Potsdam).Although well-suited for real-time data collection andanalysis, these systems do not currently provide advanced featuresfor managing the infrastructure of a seismic network,such as state-of-health monitoring of the instrumentation ortracking all the network appliances.Trying to fill this gap, Instrumental Software Technologies(ISTI 2008) has recently developed SeisNetWatch(SeisNetWatch 2008), a tool for monitoring and controllingthe data quality and the status of several types of data loggersand real-time seismic management systems. This desktop- andWeb-accessible tool features a core system and a user interfacewritten in Java, plus several “agents” each interacting with aparticular piece of hardware or system.During the development of the Irpinia Seismic Network(ISNet) in southern Italy (Weber et al. 2007), we decided toaddress our needs of hardware monitoring and data managementby developing our own solution, a Web-based applicationcalled SeismNet Manager. The application is designed asa graphical front-end to ISNet for internal and external usersof the network, as well as its administrators, with an interfacethat is simple to use.SeismNet Manager leverages an instrument database anda seismic database to keep track of the hardware componentsthat comprise the network (such as stations, servers, devices)and the data they produce (such as recorded waveforms andevents). The application, universally accessible through a Webbrowser, fulfills the following needs:• to keep a detailed inventory of the multiple componentsthat constitute a seismic network, including stations, sensors,data loggers, network hardware, generic hardware,data servers, and communication links;• to maintain a historical record of the installations and ofthe configuration details, as well as of the mutual connectionsof said components;• to perform real-time monitoring of some of the devices(hardware state and “health” problems, quality of theoutput) for alerting network operators of problems andcomplementing the seismic data;• to manage the seismic data produced by the network,obtained either through automatic data retrieval proceduresor manual insertion by administrators (detected events, seismic recordings, parametric information) andto perform some routine tasks on returned data, includinginspection, filtering, picking, and flagging.• to offer a Web-based interface that lets data consumers ornetwork operators insert, edit, search, download and visualizeall the available information (as tables, graphs, maps,waveform plots, and 3D renderings).To accomplish these goals, which are not specific to ISNet butare shared by most seismic networks, we made use of opensourcetechnological solutions such as Linux (Debian 2008),PostgreSQL (PostgreSQL 2008), and Tomcat (Tomcat 2008).Flexibility and configurability was a priority, so that we couldtailor SeismNet Manager to the specific needs and actual hardwareof different networks and could manage multiple networks.At the same time, SeismNet Manager is not designedas a “be-all do-all” system performing every task needed in aseismic network, some of which are better left to specializedand standard software packages. For instance, in ISNet thecontinuous data acquisition and storage from the stations andthe real-time seismic data processing for seismic early warningare implemented elsewhere, as discussed below. SeismNetManager is thus built on top of the various elements and subsystemsalready operating in a network. http://hdl.handle.net/2122/6048 Titolo: SeismNet Manager - A web application to manage hardware and data of a seismic network<br/><br/>Autori: Elia, L.; AMRA Scarl; Satriano, C.; AMRA Scarl; Iannaccone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: The paper gives a review of the open source and commercial seismic network monitoring tools currently available, and discusses in detail the development of SeismNet Manager used for the Irpinia Seismic Network (ISNet). An overview of the network is also given, with the flow of data from station to data center. The SeismNet Manager features are discussed in relation to the operation of this network, before going into specifics about how the application actually works. The paper gives a description of the application and its use in data acquisition of the Irpinia Seismic Network. http://hdl.handle.net/2122/6035 Titolo: Insights into fluid circulation across the Pernicana Fault (Mt. Etna, Italy) and implications for flank instability<br/><br/>Autori: Siniscalchi, A.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Tripaldi, S.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Piscitelli, S.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy; Balasco, M.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy; Behncke, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Magri, C.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Naudet, V.; Université Bordeaux 1, Geosciences Hydrosciences Material and Constructions, GHYMAC-EA 4134, Talence, F-33405, France; Rizzo, E.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy<br/><br/>Abstract: We conducted geophysical–geochemical measurements on a ∼2 kmN–S profile cutting across the PernicanaFault, one of the most active tectonic features on the NE flank of Mt. Etna. The profile passes from theunstable E flank of the volcano (to the south) to the stable N flank and significant fluctuations in electricalresistivity, self-potential, and soil gas emissions (CO2, Rn and Th) are found. The detailed multidisciplinaryanalysis reveals a complex interplay between the structural setting, uprising hydrothermal fluids, meteoricfluids percolating downwards, ground permeability, and surface topography. In particular, the recoveredfluid circulation model highlights that the southern sector is heavily fractured and faulted, allowing theformation of convective hydrothermal cells. Although the existence of a hydrothermal system in a volcanicarea does not surprise, these results have great implications in terms of flank dynamics at Mt. Etna. Indeed,the hydrothermal activity, interacting with the Pernicana Fault activity, could enhance the flank instability.Our approach should be further extended along the full extent of the boundary between the stable andunstable sectors of Etna for a better evaluation of the geohazard in this active tectonic area. http://hdl.handle.net/2122/6032 Titolo: Theoretical study on SO2 and ash volcanic plume retrievals using ground TIR camera. Sensitivity analysis and retrieval procedure developments<br/><br/>Autori: Corradini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Tirelli, C.; Università La Sapienza Roma; Gangale, G.; Università di Modena e Reggio Emilia; Pugnaghi, Sergio; Università di Modena e Reggio Emilia; Carboni, E.; Atmospheric, Oceanic, and Planetary Physics, Atmospheric, Oceanic, and Planetary Physics, Clarendon Laboratory, University of Oxford<br/><br/>Abstract: In this paper, a sensitivity analysis and procedure development for volcanic-plume sulfur dioxide and ash retrievals using ground thermal infrared camera have been carried out. The semiconductor device camera, considered as a reference, has a spectral range of 8–14 μm with noise equivalent temperature difference that is better than 100 mK at 300 K. The camera will be used to monitor and assess the hazards of Mt. Etna volcano to mitigate the risk and impact of volcanic eruptions on the civil society and transports. A minimum number of filters have been selected for sulfur dioxide (SO2) and volcanic ash retrievals.The sensitivity study has been carried out to determine the SO2 and volcanic ash minimum concentration detectable by the system varying the camera geometry and the atmospheric profiles. Results show a meaningful sensitivity increase considering high instrument altitudes and low camera-elevation angles. For all geometry configurations and monthly profiles, the sensitivity limit varies between 0.5 and 2 g · m−2 for SO2 columnar abundance and between 0.02 and 1 for ash optical depth. Two procedures to detect SO2 and ash, based on the least square fit method and on the brightness temperature difference (BTD) algorithm, respectively, have also been proposed. Results show that high concentration of atmospheric water vapor columnar content significantly reducesthe ash-plume effect on the BTD. A water vapor-correction procedure introduced improves the ash retrievals and the cloud discrimination in every season, considering all the camera geometries. http://hdl.handle.net/2122/5806 Titolo: INTEGRATED ANALYSIS OF GROUND DISPLACEMENT DATA, SEISMIC ACTIVITY AND MORPHOMETRIC DATA OF THE CAMPI FLEGREI (CAMPANIA, SOUTHERN ITALY) 2000-2006 RECENT BRADYSEISMIC CRISES, IN GIS ENVIRONMENT.<br/><br/>Autori: Ricco, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Aquino, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Del Gaudio, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Alessio, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Nappi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: In this paper the results of an integratedanalysis of ground displacement data, localseismic activity and DEM image analysis, in GISenvironment, which has been performed for theCampi Flegrei volcanic area, are presented anddiscussed. The study has been carried out for therecent bradyseismic crises of 2000-2006, with theaim of working out a preliminary interpretation ofthe recent dynamics of the area. http://hdl.handle.net/2122/5766 Titolo: The contribution of synchrotron X-ray computed microtomography to understanding volcanic processes<br/><br/>Autori: Polacci, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Mancini, L.; SYRMEP Group, Sincrotrone Trieste SCpA, Basovizza (Trieste), Italy; Baker, D. R.; Earth and Planetary Sciences, McGill University, GEOTOP-UQUAM-McGill Research Centre, Montreal, QC H3A2A7, Canada; Sincrotrone Trieste SCpA, Basovizza (Trieste), Italy.<br/><br/>Abstract: A series of computer microtomography experiments are reported which were performed by using a third-generation synchrotron radiation source on volcanic rocks from various active hazardous volcanoes in Italy and other volcanic areas in the world. The applied technique allowed the internal structure of the investigated material to be accurately imaged at the micrometer scale and three-dimensional views of the investigated samples to be produced as well as three-dimensional quantitative measurements of textural features. Thegeometryof thevesicle (gas-filledvoid) network in volcanic products of both basaltic and trachytic compositions were particularly focused on, as vesicle textures are directly linked to the dynamics of volcano degassing. This investigation provided novel insights into modes of gas exsolution, transport and loss in magmas that were not recognized in previous studies using solely conventional two- dimensional imaging techniques. The results of this study are important to understanding the behaviour of volcanoes and can be combined with other geosciences disciplines to forecast their future activity. http://hdl.handle.net/2122/5745 Titolo: Dissolution/crystallization kinetics recorded in the 2002–2003 lavas of Stromboli (Italy)<br/><br/>Autori: Fornaciai, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Landi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Armenti, P.; Dipartimento di Scienze della Terra, University of Pisa, Pisa, Italy<br/><br/>Abstract: On 28 December 2002, new vents opened on the flanks of Stromboli, just below the summit craters, interrupting the persistent activity of the volcano with a 7-month-long effusive eruption. We here report on the plagioclase size distribution (PlgSD) in lava samples collected following the chronology of the 2002–2003 eruption. Data reveal a linear PlgSD similar to that found in samples of normal Stromboli activity, indicating that the switch from Strombolian explosive to effusive activity is not associated with changes in texture. Nevertheless, the crystal size distribution slopes and intercepts exhibit slight sinusoidal temporal variations that are here ascribed to a magma supply mechanism able to induce “resonance” in the crystal size distribution, with an amplitude that depends on the supply rate. http://hdl.handle.net/2122/5737 Titolo: Morphometry of scoria cones located on a volcano flank: A case study from Mt. Etna (Italy), based on high-resolution LiDAR data<br/><br/>Autori: Favalli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Karátson, D.; Department of Physical Geography, Eötvös University, Budapest, Hungary; Geoscience Center, University of Göttingen, Göttingen, Germany; Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Pareschi, M. T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia<br/><br/>Abstract: By using new high-resolution (2 m) digital elevation model derived from the 2005 LiDAR survey of Mt. Etna volcano (Italy), our study measured the classical morphometrical parameters for scoria cones, i.e. Wco (cone width), Wcr (crater diameter), H (cone height) as well as volume, inclination of cone slope and substrate, and a number of other parameters for 135 scoria cones of Mt. Etna. Volume and age distribution of cones shows that there is no direct structural control on their emplacement in terms of Etna's rift zones. The cones are progressively smaller in size toward summit, which can be explained by the large volcano's feeding system and progressively frequent lava burial toward top.A careful analysis of H/Wco ratio (determined as 0.18 for other volcanic fields worldwide) shows that this ratio strongly depends on (1) the calculation method of H and (2) lava burial of cone. For Etnean cones, applying an improved method for calculating H relative to the dipping substrate results in a significantly lowered standard H/Wco ratio (0.137), which in turn questions the validity of the classical value of 0.18 in the case of large central volcanoes. The reduction of the ratio is not only due to methodology but also to the common lava burial. This can be expressed even better if Hmean is used instead of Hmax (Hmean/Wco = 0.098). Using this measure, at Etna, well formed cones have higher ratios than structurally deformed (e. g. double or rifted) cones.Furthermore, although the sampled scoria cones at Etna have formed in a relatively narrow time interval (< 6500 yrs BP), there is a slight decrease in H/Wco corresponding to erosional changes detected globally (H/Wco = 0.143, 0.135 and 0.115 for three age classes of Etna's scoria cones, corresponding to average slopes of 26.6, 23.9 and 23.7°). Because the morphometrical effect of position on a dipping substrate as well as lava burial exceeds the effect of erosion, we call attention to use caution in simply using the H/Wco ratio of scoria cones for detecting age, especially on large active volcanoes. http://hdl.handle.net/2122/5735 Titolo: Landsat 5 TM images and DEM in lithologic mapping of Payen Volcanic Field (Mendoza Province, Argentina)<br/><br/>Autori: Fornaciai, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Bisson, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Del Carlo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Pasquarè, G.; Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milano, Italy<br/><br/>Abstract: Satellite image such as Landsat 5 TM scene provides excellent representation of Earth and synoptic view of large geographic areas in different band combination. Landsat TM images allow automatic and semi-automatic classification of land cover, nevertheless the software frequently may have some difficulties in distinguishing between similar radiometric surfaces. In this case, the use of Digital Elevation Model (DEM) can be an important tool to identifydifferent surface covers. In this study, several False Color Composite (FCC) of Landsat 5 TM Image, DEM and the respective draped image of them, were used to delineate lithological boundaries and tectonic features of regional significance of the Payen Volcanic Field (PVF). PVF is a Quaternary fissural structure belonging to the back-arc extensional area of the Andes in the Mendoza Province (Argentina) characterized by many composite basaltic lava flow fields. The necessityto identify different lava flows with the same composition, and then with same spectral features, allows to highlight the improvement of synergic use of TM images and shaded DEM in the visual interpretation. Information obtained from Satellite data and DEM have been compared with previous geological maps and transferred into a topographical base map. Based on these data a new lithological map at 1:100.000 scale has been presented.