http://hdl.handle.net/2122/237 2013-05-20T23:53:35Z http://hdl.handle.net/2122/8700 Title: Magnetic anomalies of steel drums: a review of the literature and research results of the INGV Authors: Marchetti, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sapia, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The detection and evaluation of the status of disposal sites that contain hazardous waste materials is becoming an increasingly important element in environmental investigations. Close cooperation between the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Volcanology and Geophysics) in Rome and the Italian environmental police has resulted in numerous underground investigations of different buried materials. Among the geophysical investigation tools, magnetometry is the most effective, rapid and precise of all of the geophysical methods for localizing buried steel drums. Analysis of magnetic map anomalies can provide a variety of information about buried materials, including extension, distribution and depth, with processing of the acquired magnetic data. This information is also very useful in case of excavations that are aimed at the recovery of hazardous waste. This study determines the most relevant analyses reported in the literature, with modeling of magnetometric methods for environmental applications both theoretically and experimentally. Some studies and research results achieved by the INGV in relation to magnetic anomalies produced by buried steel drums are also reported, as found in field operations and as achieved from test sites. 2013-04-18T22:00:00Z http://hdl.handle.net/2122/8683 Title: Repeat-station surveys: implications from chaos and ergodicity of the recent geomagnetic field Authors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Qamili, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cianchini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The present geomagnetic field is chaotic and ergodic: chaotic because it can no longer be predicted beyond around 6 years; and ergodic in the sense that time averages correspond to phase-space averages. These properties have already been deduced from complex analyses of observatory time series in a reconstructed phase space [Barraclough and De Santis 1997] and from global predicted and definitive models of differences in the time domain [De Santis et al. 2011]. These results imply that there is a strong necessity to make repeat-station magnetic surveys more frequently than every 5 years. This, in turn, will also improve the geomagnetic field secular variation models. This report provides practical examples and case studies. 2013-04-17T22:00:00Z http://hdl.handle.net/2122/8620 Title: Italian Magnetic Network and Geomagnetic Field Maps of Italy at year 2010.0 Authors: Dominici, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sperti, M.; Istituto Geografico Militare, Firenze; Manzo, G.; Istituto Geografico Militare, Firenze; Maseroli, R.; Istituto Geografico Militare, Firenze Abstract: In the frame of a long-time collaboration between INGV (Istituto Nazionale di Geofisica e Vulcanologia) and IGMI (Istituto Geografico Militare Italiano), also in the years 2009 and 2010 a survey of 131 repeat stations of the Italian Magnetic Network (including 2 observatories, 11 stations in Albania and 3 in Corsica and 1 in Malta) was carried out. In this paper the procedures for magnetic measurements and data elaboration are described. Furthermore, for all the repeat stations data reduced at of the measurement day, at the epoch 2010.0; are presented. At the same epoch the coefficients for normal fields were determined for all the data, in order to draw the new maps of the geomagnetic field elements (D, H, Z and total field F) at the year 2010.0, at 1: 2 000 000 scale. All these maps were created by mean of interpolation procedures on GIS platform. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8591 Title: Italian Magnetic Network and magnetic reference fields at 2010.0 Authors: Dominici, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Di Ponzio, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Miconi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The Istituto Nazionale di Geofisica e Vulcanologia (INGV) has systematically undertaken the task of making measurements of the Earth's magnetic field in Italy. By tradition and because of the elongated geometric shape of our peninsula and islands, in Italy, a grid of more than 110 points, called the first order repeat stations, with an average spacing around 55-60 km, is in operation. Over this grid the measurements are repeated regularly, every 5 years. A survey of 131 repeat stations of the Italian Magnetic Network (including 2 observatories, 11 stations in Albania, 3 stations in Corsica and 1 in Malta) was carried out between 2009 and 2010 with the main purpose of updating our magnetic cartography. We describe the characteristics of magnetic first and second order networks, the magnetic measurements and the data reduction procedure. In agreement with the recommendations of MagNetE Committee, we report new repeat station data measured and reduced at 2010.0. An analytical expression, a second order polynomial, in latitude and longitude for the field elements, was determined, and coefficients for 2010.0 and average secular variation over the period 2005-2010, were obtained. The new maps for Italy, for D, F, H and Z at the epoch 2010.0, are shown. A selection of stations from the Italian Magnetic Network, based on their low values of anomaly with respect to a 'normal' field, is also proposed for future surveys. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8086 Title: Influence of solar activity on magnetic network measurements Authors: Tozzi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Dominici, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The influence of solar activity on magnetic measurements taken during the Italian repeat station surveys performed in 1999/2000 and 2009/2010 has been investigated. A method to estimate the difference between the 2000.0 and 2010.0 surveys in terms of the “residual” (i.e. not completely reduced) external contribution is proposed. This method is also based on the removal of the contribution due to the magnetic field of internal origin by means of CHAOS3 model from magnetic repeat station measurements. The origin of the observed differences is interpreted in terms of the very different level of solar activity between 2000.0 and 2010.0. Indeed, results seem to suggest that differences could be attributed to the enhanced ring current intensity during a phase of solar maximum. The investigation of the spatial patterns of these differences suggests that they could be reduced by introducing a larger number of variometer stations, especially during surveys undertaken under conditions of high solar activity. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7869 Title: Correlation of welded ignimbrites on Pantelleria (Strait of Sicily) using paleomagnetism Authors: Speranza, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Di Chiara, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Rotolo, S. G.; Dipartimento di Scienze della Terra e del Mare (DISTeM), Università di Palermo, Via Archirafi 36, 90123 Palermo, Italy Abstract: Although the oldest volcanic rocks exposed at Pantelleria (Strait of Sicily) are older than 300 ka, most of the island is covered by the 45–50 ka Green Tuff ignimbrite, thought to be related to the Cinque Denti caldera, and younger lavas and scoria cones. Pre-50 ka rocks (predominantly rheomorphic ignimbrites) are exposed at isolated sea cliffs, and their stratigraphy and chronology are not completely resolved. Based on volcanic stratigraphy and K/Ar dating, it has been proposed that the older La Vecchia caldera is related to ignimbrite Q (114 ka), and that ignimbrites F, D, and Z (106, 94, and 79 ka, respectively) were erupted after caldera formation. We report here the paleomagnetic directions obtained from 23 sites in ignimbrite P (133 ka) and four younger ignimbrites, and from an uncorrelated (and loosely dated) welded lithic breccia thought to record a caldera-forming eruption. The paleosecular variation of the geomagnetic field recorded by ignimbrites is used as correlative tool, with an estimated time resolution in the order of 100 years. We find that ignimbrites D and Z correspond, in good agreement with recent Ar/Ar ages constraining the D/Z eruption to 87 ka. The welded lithic breccia correlates with a thinner breccia lying just below ignimbrite P at another locality, implying that collapse of the La Vecchia caldera took place at ~130–160 ka. This caldera was subsequently buried by ignimbrites P, Q, F, and D/Z. Paleomagnetic data also show that the northern caldera margin underwent a ~10° west–northwest (outwards) tilting after emplacement of ignimbrite P, possibly recording magma resurgence in the crust. 2012-02-29T23:00:00Z http://hdl.handle.net/2122/7261 Title: Repeat Station Activities Authors: Barraclough, D. R.; British Geological Survey, Edinburgh, U. K.; De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Editors: Mandea, M.; Institut de Physique du Globe, Paris, France; Korte, M.; GFZ German Research Centre for Geosciences Abstract: A repeat station is a site whose position is accurately known and where accurate measurements of the geomagnetic field vector are made at regular intervals in order to provide information about the secular variation of the geomagnetic field. In this chapter we begin by giving a brief history of the development of repeat station networks. We then describe the instruments used to make measurements at a repeat station. These include fixing the position of the station, finding the direction of true north and measuring the components of the geomagnetic field. Emphasis is given to techniques and instruments that are in current use. We next discuss the procedures that are used to reduce the measurements to a usable form and consider the uses to which the reduced data are put. Finally, we discuss the continued importance of such data in the present era of satellite geomagnetic surveys. 2011-07-31T22:00:00Z http://hdl.handle.net/2122/7207 Title: Computational Intelligence Methods for Underwater Magnetic-based Protection Systems Authors: Decherchi, S.; Dept. Drug Discovery and Development- Italian Institute of Technology, Morego, Genova, Italy; Leoncini, D.; Dept. Biophysical and Electronic Eng., University of Genoa, Genova, ITALY; Gastaldo, P.; Dept. Biophysical and Electronic Eng., University of Genoa, Genova, ITALY; Zunino, R.; Dept. Biophysical and Electronic Eng., University of Genoa, Genova, ITALY; Faggioni, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Soldani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Magnetic-based detection technologies for undersea protection systems are very effective in monitoring critical areas where weak signal sources are difficult to identify (e.g. diver intrusion in proximity of the seafloor). The complexity of the involved geomagnetic phenomena and the nature of the target detection strategy require the use of adaptive methods for signal processing. The paper shows that Computational Intelligence (CI) models can be integrated with those magnetic-based technologies, and presents an effective, reliable system for adaptive undersea protection. Two different CI paradigms are successfully tested for the specific application task: Circular BackPropagation (CBP) and Support Vector Machines (SVMs). Experimental results on real data prove the advantage of the integrated approach over existing conventional methods. Individual CI components and the overall detection system have been verified in real experiments. 2011-07-30T22:00:00Z http://hdl.handle.net/2122/7206 Title: Un nuovo sistema di alimentazione per l'Osservatorio Geomagnetico di Lampedusa Authors: Fois, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Biasini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Benedetti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Scopo di questa monografia è quello di fornire una descrizione delle attività svolte per realizzare e perfezionare la funzionalità dell’osservatorio geomagnetico di Lampedusa. A tal fine saranno descritte brevemente le finalità scientifiche di questo osservatorio geomagnetico remoto, le modifiche e le migliorie apportate alla strumentazione dell’osservatorio per risolvere gli iniziali problemi di funzionamento del sistema di misura. Tali modifiche e migliorie hanno riguardato: il software di gestione del sistema di acquisizione, che controlla gli strumenti di misura del campo magnetico; il regolatore di tensione per pannelli solari che fornisce energia a tutti gli apparati. Il modello commerciale di regolatore è stato sostituito da un prototipo progettato e realizzato nei laboratori INGV, che pur meno sofisticato dei tanti modelli in commercio, garantisce il buon funzionamento dei magnetometri scalari ad effetto Overhauser (prodotti dalla GEM System) e quindi la corretta misura assoluta dell’intensità totale del campo magnetico terrestre. 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7115 Title: CO2 and He degassing at El Chichón volcano, Chiapas, Mexico: gas flux, origin and relationship with local and regional tectonics Authors: Mazot, A.; Instituto de Geofisica UNAm Mexico City Mexico; Rouwet, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Taran, Y.; Instituto de Geofisica UNAM Mexico City Mexico; Inguaggiato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Varley, N.; Universidad de Colima, Colima Mexico Abstract: During 2007–2008, three CO2 flux surveys were performed on El Chichón volcanic lake, Chiapas, Mexico, with an additional survey in April 2008 covering the entire crater floor (including the lake). The mean CO2 flux calculated by sequential Gaussian simulation from the lake was 1,190 (March 2007), 730 (December 2007) and 1,134 g m−2 day−1 (April 2008) with total emission rates of 164±9.5 (March 2007), 59±2.5 (December 2007) and 109±6.6 t day−1 (April 2008). The mean CO2 flux estimated from the entire crater floor area was 1,102 g m−2 day−1 for April 2008 with a total emission rate of 144±5.9 t day−1. Significant change in CO2 flux was not detected during the period of survey, and the mapping of the CO2 flux highlighted lineaments reflecting the main local and regional tectonic patterns. The 3He/4He ratio (as high as 8.1 RA) for gases in the El Chichón crater is generally higher than those observed at the neighbouring Transmexican Volcanic Belt and the Central American Volcanic Arc. The CO2/3He ratios for the high 3He/4He gases tend to have the MORB-like values (1.41×109), and the CO2/3He ratios for the lower 3He/4He gases fall within the range for the arc-type gases. The high 3He/4He ratios, the MORB-like CO2/3He ratios for the high 3He/4He gases and high proportion of MORB-CO2 (M=25 ±15%) at El Chichón indicate a greater depth for the generation of magma when compared to typical arc volcanoes. 2011-05-16T22:00:00Z