http://hdl.handle.net/2122/274 2013-05-20T13:56:22Z http://hdl.handle.net/2122/8701 Title: Testing the IONORT-ISP system: A comparison between synthesized and measured oblique ionograms Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Makris, J.; Technological Educational Institute of Crete, P.O. Box 1939 Chania, Crete, Greece Abstract: The three-dimensional (3-D) electron density representation of the ionosphere computed by the assimilative IRI-SIRMUP-P (ISP) model was tested using IONORT (IONOspheric Ray-Tracing), a software application for calculating a 3-D ray-tracing for high frequency (HF) waves in the ionospheric medium. A radio link was established between Rome (41.8°N, 12.5°E) in Italy, and Chania (35.7°N, 24.0°E) in Greece, within the ISP validity area, and for which oblique soundings are conducted. The ionospheric reference stations, from which the autoscaled foF2 and M(3000)F2 data and real-time vertical electron density profiles were assimilated by the ISP model, were Rome (41.8°N, 12.5°E) and Gibilmanna (37.9°N, 14.0°E) in Italy, and Athens (38.0°N, 23.5°E) in Greece. IONORT was used, in conjunction with the ISP and the International Reference Ionosphere (IRI) 3-D electron density grids, to synthesize oblique ionograms. The comparison between synthesized and measured oblique ionograms, both in terms of the ionogram shape and the maximum usable frequency characterizing the radio path, demonstrates both that the ISP model can more accurately represent real conditions in the ionosphere than the IRI, and that the ray-tracing results computed by IONORT are reasonably reliable. 2013-05-02T22:00:00Z 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/2122/8652 Title: A Multidisciplinary Study of the DPRK Nuclear Tests Authors: Carluccio, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Giuntini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Materni, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Chiappini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bignami, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Ajello Caracciolo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pignatelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Stramondo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Console, R.; Chiappini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The Democratic People Republic of Korea announced two underground nuclear tests carried out in their territory respectively on October 9th, 2006 and May 25th, 2009. The scarce information on the precise location and the size of those explosions has stimulated various kinds of studies,mostly based on seismological observations, by several national agencies concerned with theNuclear Test Ban Treaty verification.Weanalysed the available seismological data collected through a global high-quality network for the two tests. After picking up the arrival times at the various stations, a standard location program has been applied to the observed data. If we use all the available data for each single event, due to the different magnitude and different number of available stations, the locations appear quite different. On the contrary, if we use only the common stations, they happen to be only few km apart from each other and within their respective error ellipses. A more accurate relative location has been carried out by the application of algorithms such as double difference joint hypocenter determination (DDJHD) and waveform alignment. The epicentral distance between the two events obtained by these methods is 2 km, with the 2006 event shifted to the ESE with respect to that of 2009. We then used a dataset of VHR TerraSAR-X satellite images to detect possible surface effects of the underground tests. This is the first ever case where these highly performing SAR data have been used to such aim. We applied InSAR processing technique to fully exploit the capabilities of SAR data to measure very short displacements over large areas. Two interferograms have been computed, one co-event and one post-event, to remove possible residual topographic signals. A clear displacement pattern has been highlighted over a mountainous area within the investigated region, measuring a maximum displacement of about 45 mm overall the relief. Hypothesizing that the 2009 nuclear test had been carried out close to the area where the displacement has been observed through the DInSAR technique, its relation with the epicenter location obtained through seismological processing has been discussed as a possible alternative hypothesis with respect to the preferred solutions reported by the nuclear explosion database (NEDB). The distance of about 10 km between the two places can be considered acceptable in light of the possible systematic location shifts commonly observed in the seismological practice over a global scale. The difference between the mb magnitudes of the two tests could reflect differences in geological conditions of the two test sites, even if the yield of the two explosions had been the same. 2012-12-28T23:00:00Z http://hdl.handle.net/2122/8496 Title: Are the source models of the M7.1 1908 Messina Straits earthquake reliable? Insights from a novel inversion and a sensitivity analysis of levelling data Authors: Aloisi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Bruno, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Cannavo', F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Ferranti, L.; Dipartimento di Scienze della Terra, Universita' di Napoli; Mattia, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Monaco, C.; Dipartimento di Scienze Geologiche, Universita' di Catania; Palano, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: For decades, many authors have attempted to define the location, geometry and kinematics of the causative fault for the 1908 December 28, M 7.1 earthquake that struck the Messina Straits between Sicily and Calabria (southern Italy). The coseismic displacement caused a predominant downwarping of the Straits and small land uplift away from it, which were documented by levelling surveys performed 1 yr before and immediately after the earthquake. Most of the source models based on inversion of levelling data suggested that the earthquake was caused by a low angle, east-dipping blind normal fault, whose upper projection intersects the Earth surface on the Sicilian (west) side of the Messina Straits.An alternative interpretation holds that the causative fault is one of the high-angle, west-dipping faults located in southern Calabria, on the eastern side of the Straits, and may in large part coincide with the mapped Armo Fault. Here, we critically review the levelling data with the aim of defining both their usefulness and limits in modelling the seismogenic fault. We demonstrate that the levelling data alone are not capable of discriminating between the two oppositely dipping fault models, and thus their role as a keystone for modellers is untenable. However, new morphotectonic and geodetic data indicate that the Armo Fault has very recent activity and is accumulating strain. The surface observations, together with appraisal ofmacroseismic intensity distribution, available seismic tomography and marine geophysical evidence, lends credit to the hypothesis that the Armo and possibly the S. Eufemia faults are part of a major crustal structure that slipped during the 1908 earthquake. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8103 Title: The effect of collisions in ionogram inversion Authors: Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The results of this paper demonstrate that the effect of collisions on the group refraction index is small, when the ordinary ray is considered. If, however, in order to improve the performance of a system for automatic interpretation of ionograms, the information contained in ordinary and extraordinary traces is combined, the effect of collisions between the electrons and neutral molecules should be taken into account for the extraordinary ray. The magnitude of these differences is generally very small and must be compared with the resolution in the virtual vertical height of the ionosonde, resolution which is typically of the order of few kilometers. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8056 Title: Upper mantle structure below the European continent: Constraints from surface-wave tomography and GRACE satellite gravity data Authors: Tondi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Schivardi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Molinari, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Morelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Abstract: We here exploit fundamental mode Rayleigh and Love seismic wave information and the high resolution satellite global gravity model GGM02C to obtain a 1° × 1° 3-D image of: (a) upper-mantle isotropic shear-wave speeds; (b) densities; and (c) density-vS coupling below the European plate (20°N–90°N) (40°W–70°E). The 3-D image of the density-vS coupling provides unprecedented detail of information on the compositional and thermal contributions to density structures. The accurate and high-resolution crustal model allows us to compute a reliable residual topography to understand the dynamic implications of our models. The correlation between residual topography and mantle residual gravity anomalies defines three large-scale regions where upper mantle dynamics produce surface expression: the East European Craton; the eastern side of the Arabian Plate; and the Mediterranean Basin. The effects of mantle convection are also clearly visible at: (1) the Eastern Sirt Embayment; (2) the West African Craton northern margins; (3) the volcanically active region of the Canarian Archipelago; (4) the northern edge of the Central European Volcanic Province; and (5) the Northeastern part of the Atlantic Ocean, between Greenland and Iceland. Strong connections are observed among areas of weak radial anisotropy and areas where the mantle dynamics show surface expression. Although both thermal and additional dependencies have been incorporated into the density model, convective down-welling in the mantle below the East European Craton is required to explain the strong correlation between the estimated negative mantle residual anomalies and the negative residual topography. 2012-09-04T22:00:00Z http://hdl.handle.net/2122/8028 Title: Parallel ‘large’ dense matrix problems: application to 3D joint inversion of seismological and gravity data Authors: Tondi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Cavazzoni, C.; CINECA, Interuniversity Computing Centre, Via Magnanelli 6/3, 40033 Casalecchio di Reno (BO), Italy; Danecek, P.; Univ Granada, Inst Andaluz Geofis, E-18071 Granada, Spain; Morelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Abstract: To obtain accurate and reliable estimations of the major lithological properties of the rock within a studied volume, geophysics uses the joint information provided by different geophysical datasets (e.g. gravimetric, magnetic, seismic). Representation of the different types of information entering the problem using probability density functions can provide the mathematical framework to formulate their combination. The maximum likelihood estimator of the resulting joint posterior probability density functions leads to the solution of the problem. However, one key problem appears to limit the use of this solver to an extensive range of real applications: information coming from potential fields that implies the presence of dense matrices in the resolving estimator. It is well known that dense matrix systems rapidly challenge both the algorithms and the computing platforms, and are not suited to high-resolution 3D geophysical analysis. In this study, we propose a procedure that allows us to obtain fast and reliable solutions of the joint posterior probability density functions in the presence of large gravity datasets and using sophisticated model parametrization. As it is particularly CPUconsuming, this 3D problem makes use of parallel computing to improve the performance and the accuracy of the simulations. Analysis of the correctness of the results, and the performance on different parallel environments, shows the portability and the efficiency of the code. This code is applied to a real experiment, where we succeed in recovering a 3D shear-wave velocity and density distribution within the upper mantle of the European continent, satisfying both the seismological and gravity data. On a multiprocessor machine, we have been able to handle forward and inverse calculations with a dense matrix of 215.66 Gb in 18 min, 20 s and 20 min, 54 s, respectively. 2012-10-31T23:00:00Z http://hdl.handle.net/2122/7965 Title: A RESPER probe for measurements of RESistivity and PERmittivity Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Editors: Beatrice besson; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121, Saarbrücken, Germany Abstract: The electrical RESistivity and dielectric PERmittivity measuring device (RESPER) for non-invasive investigation of media is an exploiting electrical induction by means of capacitive coupling with media as terrestrial soils and concretes. The device utilizes a four-electrode probe to inject a radio frequency into a medium and register an induced current. Complex transfer impedance can be determined from a ratio between a potential measured across two electrodes, and an induced current flowing in the medium. Electrical parameters of resistivity and permittivity characterizing the medium can be established from the transfer impedance, using inversion formulas that also take into account the geometric ratio and position of the electrodes. The device exploits the in-phase and quadrature under sampling technique which, together with numerical operations performed by a microcontroller, allows the device to attain a required performance. It is possible to execute a number of numerical integrations which, combined with some circuit solutions, can reduce the amplitude and phase errors of the acquired signal. The device can operate at variable frequency, maintaining a suitable under-sampling frequency to fully exploit the analogical-digital acquisition performance both in velocity and dynamic range. 2012-05-15T22:00:00Z http://hdl.handle.net/2122/7533 Title: Microzonazione sismica di un centro abitato di piccole dimensioni: il caso studio di Sant’Agata Fossili (AL) Authors: Podestà, Stefano; DICAT – Università di Genova; Conte, Riccardo; Regione Piemonte-Direzione Opere Pubbliche, Difesa del suolo ed Economia Montana e Foreste, Torino; Compagnoni, Massimo; DIS-Politecnico di Milano; Di Capua, Giuseppe; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia; Di Giulio, Giuseppe; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Marchetti, Marco; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Milana, Giuliano; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Passalacqua, Roberto; DICAT – Università di Genova; Peppoloni, Silvia; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia; Pergalani, Floriana; DIS-Politecnico di Milano Editors: Mezzina, Mauro; Politecnico di Bari Abstract: In questo lavoro sono descritte le attività svolte nell’ambito del Progetto Europeo Strategico RISKNAT riguardanti l’analisi di microzonazione di Sant’Agata Fossili (AL). Sono in particolare descritte tutte le indagini ed analisi numeriche condotte al fine di ottenere una microzonazione sismica di livello 3 secondo quanto previsto nelle recenti linee guida nazionali degli. Al fine inoltre di valutare le ricadute di tipo applicativo di una corretta microzonazione sismica del territorio, sono state realizzate delle simulazioni di scenario adottando come riferimento gli spettri di risposta ottenuti dall’analisi di microzonazione. Le valutazioni di scenario ottenute sono state infine confrontate con le previsioni di scenario realizzabili a priori sulla base dell’adozione degli spettri di risposta definiti nelle Norme Tecniche per le Costruzioni. 2011-09-17T22:00:00Z http://hdl.handle.net/2122/7288 Title: Imaging the multi‐level magma reservoir at Mt. Etna volcano (Italy) Authors: Aloisi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Mattia, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Ferlito, C.; Dipartimento di Geologia, Università degli Studi di Catania; Palano, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Bruno, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Cannavò, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: The continuous GPS network operating on Mt. Etna with its 36 stations is currently one of the largest worldwide. The aim of this network is the evaluation of volcanic hazard and the modelling of the active sources. In this paper, we propose an in‐depth analysis and modelling of continuous GPS data collected at Mt. Etna from May 2008 to December 2010. The analyzed period has been divided into four different coherent phases: 1) 14 May 2008–02 August 2008 (deflation of the entire GPS network); 2) 02 August 2008–14 June 2009 (deflation of the summit area and inflation at lower heights); 3) 14 June 2009–21 May 2010 (inflation of the entire GPS network); 4) 21 May 2010–31 December 2010 (inflation at medium and low heights and end of the inflation in the summit area). Analytical models indicate a non-uniform deformation style revealing spaced sources acting at different time on different segments of a multi-level magma reservoir. The Etnean plumbing system imaged here is depicted as an elongated magma reservoir that extends from the volcano body downwards to about 6.5 km below sea level (b.s.l.), sloping slightly towards the North-West, with storage volumes located at about 6.5, 2.0 and 0.0 km (b.s.l.). The changes in position of the modelled pressure sources during the analyzed time intervals indicate that, throughout the 2008 eruptive period, the deformation field was mostly driven by the upward migration of magma. On the other hand, the pattern of deformation recorded after the end of the eruption strongly suggests a significant contribution of the magma overpressure generated by the gas boiling, thus outlining the importance of volatiles content in magma. 2011-08-19T22:00:00Z