http://hdl.handle.net/2122/260 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/6069 Titolo: BET_VH: exploring the influence of natural uncertainties on long-term hazard from tephra fallout at Campi Flegrei (Italy)<br/><br/>Autori: Selva, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Costa, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Sandri, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: In this paper, we explore the effects of theintrinsic uncertainties upon long-term volcanic hazardby analyzing tephra fall hazard at Campi Flegrei, Italy,using the BET_VH model described in Marzocchi et al.(Bull Volcanol, 2010). The results obtained show thatvolcanic hazard based on the weighted average of allpossible eruptive settings (i.e. size classes and vent locations)is significantly different from an analysis basedon a single reference setting, as commonly used involcanic hazard practice. The long-term hazard mapfor tephra fall at Campi Flegrei obtained here accountsfor a wide spectrum of uncertainties which are usuallyneglected, largely reducing the bias intrinsicallyintroduced by the choice of a specific reference setting.We formally develop and apply a general method torecursively integrate simulations from different modelswhich have different characteristics in terms of spatial coverage, resolution and physical details. This outcomeof simulations will be eventually merged with field datathrough the use of the BET_VH model. http://hdl.handle.net/2122/6068 Titolo: Volcanological and structural evolution of the Ischia resurgent caldera (Italy) over the past 10 k.y.<br/><br/>Autori: De Vita, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Sansivero, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Orsi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Marotta, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Piochi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Curatori: Groppelli, G.; Viereck-Goette, L.<br/><br/>Abstract: Volcanic activity on the island of Ischia in the past 10 k.y. has included botheffusive and explosive eruptions, mainly in the eastern sector of the island. Vent location,eruption dynamics, transport mechanisms, and depositional processes have beenreconstructed for each recognized lithostratigraphic unit. Periods of quiescence havealternated with periods of very intense volcanism, mainly concentrated at ca. 5.5 kaand over the past 2.9 k.y. Volcanism has not been continuous, but it has been stronglyinfl uenced by the mechanism of a resurgence phenomenon that has affected theisland since ca. 33 ka. Therefore, it has been hypothesized that magma intrusion anduplift events have occurred intermittently. In the past 5.5 k.y., volcanic activity hasbeen invariably accompanied by the emplacement of slope instability–related deposits,illustrating that the slope instability was also induced by reactivation of verticalmovements, likely related to resurgence. http://hdl.handle.net/2122/6066 Titolo: Carbon dioxide diffuse emission from the soil: ten years of observations at Vesuvio and Campi Flegrei (Pozzuoli), and linkages with volcanic activity<br/><br/>Autori: Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Carbon dioxide flux from the soil is regularlymonitored in selected areas of Vesuvio and Solfatara(Campi Flegrei, Pozzuoli) with the twofold aim of i)monitoring spatial and temporal variations of the degassingprocess and ii) investigating if the surface phenomena couldprovide information about the processes occurring at depth.At present, the surveyed areas include 15 fixed pointsaround the rim of Vesuvio and 71 fixed points in the floorof Solfatara crater. Soil CO2 flux has been measured since1998, at least once a month, in both areas. In addition, twoautomatic permanent stations, located at Vesuvio andSolfatara, measure the CO2 flux and some environmentalparameters that can potentially influence the CO2 diffusedegassing. Series acquired by continuous stations arecharacterized by an annual periodicity that is related tothe typical periodicities of some meteorological parameters.Conversely, series of CO2 flux data arising from periodicmeasurements over the arrays of Vesuvio and Solfatara areless dependent on external factors such as meteorologicalparameters, local soil properties (porosity, hydraulic conductivity)and topographic effects (high or low ground).Therefore we argue that the long-term trend of this signalcontains the “best” possible representation of the endogenoussignal related to the upflow of deep hydrothermalfluids. http://hdl.handle.net/2122/6065 Titolo: Long term variations of the Campi Flegrei (Italy) volcanic system as revealed by the monitoring of hydrothermal activity<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Cardellini, C.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Baldini, A.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Donnini, M.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Minopoli, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Long duration time-series of the chemical composition of fumaroles and of soil CO2 flux revealthat important variations in the activity of the Solfatara fumarolic field, the most importanthydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of theCO2 concentrations, and a general decrease of the CH4 concentrations are interpreted as theconsequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor inCH4, hosted by the hydrothermal system. Contemporaneously, the H2O-CO2-He-N2 gas systemshows remarkable compositional variations in the samples collected after July 2000 with respect tothe previous ones, indicating the progressive arrival at the surface of a magmatic componentdifferent from that involved in the 1983-84 episode of volcanic unrest (1983-1984 bradyseism).The change starts in 2000 concurrently with the occurrence of relatively deep, long-period seismicevents which were the indicator of the opening of an easy-ascent pathway for the transfer ofmagmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000,this magmatic gas source is active and causes ground deformations, seismicity as well as theexpansion of the area affected by soil degassing of deeply derived CO2. Even though the activitywill most probably be limited to the expulsion of large amounts of gases and thermal energy, asobserved in other volcanoes and in the past activity of Campi Flegrei, the behavior of the system inthe future is, at the moment, unpredictable. 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/2122/6061 Titolo: Viscosity of crystal-bearing melts and its implication for magma ascent<br/><br/>Autori: Vetere, F.; Università della Calabria; Behrens, H.; Leibniz Universitat Hannover; Holtz, F.; Leibniz Universitat Hannover; Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: New experiments on the viscosity of partially crystallized andesite were performed high temperature using the falling sphere methods. Because experiments with partly crystallized samples are difficult to carry out (i.e. due to high sensitivity of phase equilibria to P,T and water content), we set up a new technique to control precisely the volume fraction and the size of crystals. We simply add zircon to the melt because: a) previous study suggested that the saturation of zircon in melts of andesitic composition as a function of both temperature and composition is low, and b) easy to crush in fixed size range.Zircon-bearing magmas were synthesized at 1473 K and 300 MPa using an internally heated gas pressure vessel. All the experimental samples were then analyzed using microprobe technique. Results gave an average value of ZrO2 dissolved in the melt of about 1.6 wt %. The solubility of Zr in andesitic melt is up to two-three times higher than predicted by literature model (Watson and Harrison, 1983).Falling sphere experiments were performed using as starting material composed of dry andesitic glass, zircon crystals (15, 30 and 40 vol%) and water. The water content of the andesitic melt after experiments ranged between 0.5 and 4.08 wt%. Image analyses show that the viscosity measurements are not affected by differences in crystals shape among the samples. Falling spheres results show a viscosity 10 times higher than that of andesitic melts for samples containing 15 vol% crystals and large discrepancies from previous literature models is found in the hydrous samples. At higher vol% of crystals we did not observe any movement of the sphere. This implies that such magmas show strongly Non-Newtonian viscosity, i.e. a threshold of accelerating force needs to be passed before the sphere could move. http://hdl.handle.net/2122/6059 Titolo: Changes in the VLP seismic source during the 2007 Stromboli eruption<br/><br/>Autori: Giudicepietro, F.; 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; Caputo, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Peluso, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; De Cesare, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Orazi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Scarpato, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Aim of this paper is to identify variations in Very-Long-Period (VLP) source associated with eruptive stylechanges at Stromboli volcano (Italy) and to retrieve information about the shallow plumbing system thatsustains the eruptive activity.We have considered a dataset of 74493 VLP events recorded during the period from January through August2007, when an effusive eruption occurred (February 27–April 2).We performed a polarization analysis of theentire dataset and divided the considered period into four sub-periods on the basis of polarizationcharacteristics. We then located the events and selected a subset of these events by applying a locationquality threshold. The high quality locations demonstrate that during the effusive eruption the VLP sourcesfirst moved downward and then moved southwestward.To retrieve information about the geometry of the structures where the source processes take place, wefurther consider a subset of events and estimate their source mechanisms by using a moment tensor sourcefunction (MTSF) inversion technique. Inversion of the waveforms of the VLP events that occurred onFebruary 27 allows us to obtain information about the dynamics of different source centroids distributedalong different portions of the shallow magmatic conduits. The structure defined by the locations and sourcemechanisms shows a greater complexity compared with previous studies and their time variations give aninsight into the kinematics of the eruption. 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/2122/6053 Titolo: Re-assessing volcanic hazard maps for improving volcanic risk communication: application to Stromboli Island, Italy.<br/><br/>Autori: Nave, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Isaia, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Barclay, J.; University of East Anglia, UK.<br/><br/>Abstract: Hazard and risk maps are tools for both mitigating against risk and informing and preparing the general public. Recent studies have highlighted that volcanic hazard and risk maps used during emergencies can be difficult to interpret. Our research focuses on evaluating and improving the efficacy of currently available maps of Stromboli volcano on Stromboli island (Italy) for the communication of volcanic hazard andrisk information. Stromboli is an active volcano characterised by persistent explosive activity, sporadic lava effusions and landslides on the volcanos northwestern flank, which sometimes generates tsunamis,most recently in 2002. This study used semi-structured interviews conducted with local legislators, administratorsand ‘enforcers’ to understand their perceptions of available risk information; to evaluate the respondents mental spatial maps; and to determine the most important components in encouraging risk-reducing behaviour in a hazardous situation. Respondents were asked to evaluate a contour map, an aerial photograph, a digital elevation model (DEM) and an innovative 3D tsunami risk map. These results enabled the development of different volcanic risk maps for use by ‘experts’ and ‘tourists’ using acontour map and a DEM (Scale 1:12.500). A 3D map focused on the tsunami risk (Scale 1:6.500) area was also produced.<br/><br/>Descrizione: Full resolution Stromboli Hazards map is available at the following link: http://www.journalofmaps.com 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.