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The knowledge of sea level in harbours is very important to manage port activities (safety of navigation, prevention of ship stranding, optimization of vessel loading, water quality control). In this article we describe the use of a software tool developed to help local authorities and working organizations to optimize navigation and avoid or manage hazardous situations due to sea level changes in port basins. This prototype application, starting from reading data coming from a monitoring station in La Spezia harbour (in North Western Italy), updates dynamically the port bathymetry based on sea level oscillations (measured in the past or real-time, or expected in the near future). Then, it detects potentially dangerous areas for a given ship moving in the basin at a certain time, by means of the idea of “virtual traffic lights”: sea level variations are provided as parameters to the application that performs the updating of the bathymetric map and the subdivision of the harbour in allowed (green)/warning (yellow)/prohibited (red) areas for each ship, based on its draft. The tool can provide a useful support interface to competent authorities to avoid or manage critical situations by detecting hazardous areas for a given vessel at a given time.

This article describes research aimed at developing a system able to support local authorities and port communities in optimizing port navigation, avoiding or managing critical situations induced by sea-level variations in harbours and minimizing environmental damages and economic losses. In the Mediterranean basin, sea-level changes are mostly due to astronomical tides, related to the gravitational attraction between Earth, Moon and Sun. Nevertheless, sea-level variations are also influenced by meteorological tides, which are geodetic adjustments of sea surface due to atmospheric pressure variations above a water basin. So, starting from monitoring or forecasting environmental parameters in harbours, the system updates port bathymetric maps based on sea-level variations (acquired in the past, measured in real-time, or expected in the future) and detects hazardous areas for a certain ship moving inside a port at a given moment, by means of the implementation of “virtual traffic lights”. The system was tested on some real situations, including the analysis of maritime accidents (stranding of ships), providing satisfactory results by correctly signalling potentially dangerous areas variable over time. The architecture of the system and results achieved using it in the ports of Livorno and Bari, in Italy, are herewith described.

The paper discusses the quantitative definition of the s/n (signal to noise ratio) by means of new computational parameters derived (and computed) by the Fourier analysis. The theme is of great relevance when the geomagnetic observed field has high transient noise and high energy content (i.e.geomagnetic signal interfered by human activity magnetic band) and when the signal analysis action is oriented to the detection of magnetic sources characterized by quasi-punctiform size, low energy level and kinetic mechanical status (i.e.uw armed terrorist). The paper shows the results obtained introducing two new informative spectral parameters: the informative capability “C” and the enhanced informative capability “eC”. These parameters are depending on the comparison of the energy of the target signal with total field energy and they are characteristics of each elementary signal. C classifies the energy of the spectrum in two metrological bands: elementary signal informative energy EI (band or single signal) and passive energy EP. This metrological classification of the energy overtakes the concept of noise: each signal is part of the noise band when it is not under observation and becomes out of the band when it is under observation (numerical observation→computation). C (and eC) allows to compute the value of the “visibility” of the informative signals in a high energy geomagnetic field (or spectrum). C is a fundamental parameter for the evaluation of the effectiveness of singularity magnetic metrology in the passive detection of small magnetic sources in high noised magnetic field.

The paper tackles the problem of reading singularities of the geomagnetic field in noisy underwater (UW) environments. In particular, we propose a novel metrological approach to measuring low-amplitude geomagnetic signals in hard noisy magnetic environments. This research action was launched to develop a detection system for enforcing the peripheral security of military bases (harbors/coasts and landbases) and for asymmetric warfare. The concept underlying this theory is the spatial stability in the temporal variations of the geomagnetic field in the observation area. The paper presents the development and deployment of a self-informed measurement system, in which the signal acquired from each sensor—observation node—is compared with the signal acquired by the adjacent ones. The effectiveness of this procedure relates to the inter-node (sensor-to-sensor) distance, L; this quantity should, on one hand, correlate the noise and, on the other hand, decorrelate the target signal. The paper presents the results obtained, that demonstrate the ability of self-informed systems to read weak magnetic signals even in the presence of very high noise in low-density ionic solutions (i.e. sea water).

Sea level oscillations are the superposition of many contributions. In particular, tide is a sea level up-down water motion basically depending on three different phenomena: the Earth-Moon-Sun gravitational relationship, the water surface fluid reaction to atmospheric meteorological dynamic, and the Newtonian vertical adjustment of the sea surface due to atmospheric pressure variations. The first tide component (astrotide) is periodic and well known in all points of the Earth surface; the second one is directly related to the meteorological phenomenon, and then it is foreseeable; the Newtonian component, on the contrary, is not readily predictable by a general hydrostatic law, because theJfactor that represents the Newtonian transfer (from the atmospheric weight to the consequent sea level) is variable in each harbor area. The analysis of the gravity field permits to forecast the sea level variation due to meteorological tide events, and its metrological analysis highlights a compensation in the inverse hydrobarometric factor to be taken into account to correctly compensate atmospheric pressure variations in semibinding basins. This phenomenon has several consequences in Harbor Waterside management and in water quality control as shown by the reported case studies and introduces a new reference parameter: the so-called Water 1000.

In the following, we report the advances made in the development of a magnetic component for peripheral monitoring of port environments for anti-intruder systems. The project was initiated with the aim of improving the detection performance of current acoustic-based anti-intruder systems, in the vicinity of quays or the seabed or in acoustic shadow zones behind natural or artificial objects. In the 5-year period from 2004 to 2008, the system has been subjected to detection-performance tests in experiments involving divers equipped with air tanks and rebreather kits in real port environments and, at the same time, the associated signal processing has been subjected to development, to enhance detection performance. In tests involving simulated diver attacks against a vessel moored alongside a quay in the port of La Spezia, the system has been proved particularly effective by detecting 9 divers out of 9.

Aeromagnetic data from the Southern Tyrrhenian Sea have been analysed, to remove the contributions of shallow and deep sources to the magnetic anomalies by applying a processing technology that increases the informative potential of the magnetic data acquired by AGIP with great accuracy, uniform distribution and high density. The aeromagnetic anomaly field has been reduced to the bottom topographic surface by the bottom reduction method. Spectral signal analysis has been carried out to separate lowand high-frequency components. The spectral reference field (SRF), obtained from the cotransformation of low frequencies, gives information about deep magnetic structures. The high-frequency components, computed from the difference between the magnetic anomaly field and the SRF, provides the spectral anomaly field (SAF). The bottom reduced magnetic anomaly field is derived by merging the highand low-frequency bands. The resulting map provides information about geotectonic features in the Southern Tyrrhenian area and shows the effectiveness of the adopted approach over traditional procedures. The magnetic cartography of Italy and its surrounding seas is made up of the following previous works: (1) the aeromagnetic anomaly map of Italy (AGIP & Servicio Geologico d’Italia (SGN) 1994; scale 1:1 000 000), obtained by processing the same data as used in this work; (2) the shaded relief magnetic anomaly map at sea level (Chiappini et al. 2000; scale 1:1 500 000); (3) the aeromagnetic anomaly map of Italy and surveyed provinces, which is the final product of data processing of the old AGIP map after some integrative surveys conducted by Eni Exploration & Production Division in 2000– 2001 in collaboration with the Istituto di Geofisica Marina (Eni Exploration–Production Division & IGMar 2002; scale 1:1 500 000). The aeromagnetic maps (AGIP & SGN 1994; Eni Exploration–Production Division & IGMar 2002) are smoothed by the effect of the data acquisition height with respect to the Chiappini et al. (2000) map, the data for which were acquired in marine and ground surveys. The Chiappini et al. map was compiled by merging the marine data of the Osservatorio Geofisico Sperimentale (OGS) of Trieste and the ground network records of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), involving many researchers for several years. This long and expensive data patchwork clearly shows differences from the previous layout and a consequent enhancement in signal informative potential. In this study the problem of smoothing, typical of aeromagnetic maps, is overcome by means of the (bottom reduction method, BTM; Faggioni et al. 2001), which reduces the topographic effect in a short time and shows more highly distinct geomagnetic anomalies with a considerable improvement of informative data content. The present procedure is based on a downward continuation to cancel spectral difference caused by the topographic distance between magnetic sources (seamounts and volcanic islands) and survey level so as to better characterize the anomalies. Main volcanic and structural features The Southern Tyrrhenian Sea represents a complex Cenozoic oceanic back-arc basin with different areas of extensional deformation as a result of lowering, spreading, subduction and magmatism (Faccenna et al. 2004). Its triangular shape is irregular, with the western margin larger than the eastern one. It is delimited on the western side by the Corsica–Sardinia block, on the southern side by Sicily and on the eastern side by the Italian mainland and the Calabrian Arc. The abyssal plain is floored by basaltic crust. Different dynamic processes have generated a volcanism associated with extension and another linked to subduction phenomena, so we find different magmatic volcanic sites: (1) northward the small circular oceanic basins of Magnaghi–Vavilov and Marsili are separated by a north–south trending structural discontinuity; (2) to the SE, the Aeolian Arc with its From: MORATTI, G. & CHALOUAN, A. (eds) 2006. Tectonics of the Western Mediterranean and North Africa. Geological Society, London, Special Publications, 262, 337–348. 0305-8719/06/$15.00 # The Geological Society of London 2006. seven volcanic edifices forms a semicircle offshore from the continental shelf of the Calabrian Arc; (3) Ustica is in a transition zone between two domains, the Tyrrhenian Basin and the Apennine– Maghrebian Chain. In the Southern Tyrrhenian Sea, because of the greater extension rate than in the northern part, there are more intense magmatic processes and thinned crust. Therefore oceanic crust occurs mostly in the southern sectors of the area (Malinverno & Ryan 1986). The deep-water volcanoes have developed through an incremental growth process. Vavilov and Magnaghi were formed in the Early Pliocene back-arc basin, Marsili dates back to the Mid-Pliocene (Faggioni et al. 1995). Aeolian volcanism and Ustica were active from the Early Pleistocene. Furthermore, geological studies and seismic reflection profiles have revealed the presence of approximately NW–SE transcurrent faults in the Southern Tyrrhenian area. The Pleistocene and present-day rise of magmas within the Tyrrhenian domain causes a very high heat flow, reaching average values of 200 mW m and a geothermal gradient locally exceeding 100 8C km in the Tyrrhenian Sea and its margins (Mongelli et al. 1989). Across the Selli Line and the Vavilov–Magnaghi basin, heat flow values are irregular and show a wider range between ,100 and .200 mWm. This is typical of young rift domains or young oceanic crust–volcanic districts subject to hydrothermal circulation (Della Vedova et al. 2000a, b). The highest values occur as minor spots within the Vavilov–Magnaghi and Marsili basin and occupy wider sectors across the Campania margin and in the Northern Sicily basin. Crustal thickness decreased from 30 km to about 10 km during middle late Miocene to Pleistocene stretching and then both intrusive and extrusive magmatism became important (Sartori et al. 2004).

The effectiveness of the time reduction procedure is the critical problem for the informative contents evaluation in the high definition (HD) geomagnetic marine surveys. The use of magnetogradiometers is a good solution for the time-reduction in the regional offshore studies but often, for technical reasons, this is not a practicable method in the very detailed coastal, canal or harbour surveys where the use of coastal base stations may be preferable. On the other hand the uncertainty of the full transferability of the coastal magnetograms to large areas of marine surveys can disrupt the time-reduced data sets by a geomagnetic residual time component. The phenomenon is related to the distance from the coastal observatory and to the homogeneity of the local magnetic characteristics of the crust. The maximum applicability distance of the time-line correction (TL) is qualitatively evaluated and is shown to be inconsistent with geomagnetic marine surveys in high definition. In this work we show a quantitative method to evaluate the stability of the coastal observatory magnetograms over the nearby marine area, together with the numerical degree of precision of the correction. The method is based on a double survey of the same profile (timer track: TT) at two different times. The surveys produce two different row data sets where the difference is related only to the geomagnetic time variations. Using the coastal observatory magnetograms we time-reduce the two data sets: if the coastal observatory magnetograms are fully coherent in the whole survey area the difference between the two reduced data sets will be zero. However, if the time variations measured in the observatory are inadequate in amplitude or phase to model the corresponding time variations in the surveyed profile (TT), the discrepancy between the time reduced data sets will not be zero. Similar TTs starting with various course from the base station permit the surveyed area to be split into sectors with variable degree of time coherence and to assign a degree of precision to the time-reduced survey.

We show the results obtained by means of a seabed reduction technique on the intensity of geomagnetic anomaly fields applied to a synthetic case and then to the real case of a geomagnetic survey of eastern Ligurian Sea (Italy). The eastern Ligurian Sea has very intense short waves anomaly fields and a sea bed that varies greatly in depth. As a result the geomagnetic space signal is characterized by a very large spectral content; in these conditions it is not possible to obtain a full sampled marine survey and vertical continuation analytic procedures and standard numerical bottom reduction based on a single vertical incremental parameter, whichever is applicable, fails to give accurate results. The present technique, which has been fine-tuned over 4 years of experimentation in environmental researchs, aims to provide a simple and efficient means to reduce the distortion of geomagnetic anomalies field caused by the variation of distance between survey plane and magnetic outcrop source position. The compensation procedure is based on evaluation, by comparison of two measurements carried out at different altitudes, of the mean vertical increment typical of each anomaly field principal frequency component bands. The component anomaly fields are then corrected by application of the corresponding vertical increments and lastly, the anomaly geomagnetic field reduced to the sea-bed is computed as Inverse Fourier Transform of a spectrum built as synthesis of the component anomaly fields' spectra. The results obtained have shown a notable increase in definition of anomaly field intensity without the production of appreciable distortions or false geomagnetic echoes.

With the decrease in energy consumption of electronic sensors, the concept of harvesting renewable energy in human surrounding becomes a must. In this context, piezoelectric generators seems promising since they can harvests mechanical vibrations and in general energy available in nature. The aim of this paper is to design a piezoelectric generators, optimized for different kind of sensors and electronic equipments, able to work under the sea or into rivers, which can work with natural water vibrations generated by solid-fluid objects interactions (Von-Karman Vortex) and then to test the effectiveness of the device developing an electronic board to analyze the behavior of the generator.

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.

This paper presents the revised aeromagnetic anomaly map of Italy and its surrounding seas, projected at reference altitude of 2500 m and geomagnetic epoch 1979.0. The magnetic data set used for the map compilation is composed of the total intensity field data acquired partly during the aeromagnetic surveys performed by the Italian National Oil Company (Agip - Direzione Esplorazione Idrocarburi) between 1971 and 1980, and during the new surveys committed by the Geophysical Corporate Services of Eni Spa - Exploration & Production Division in the years 2001-2002. In both campaigns the recorded data were very dense and uniformly distributed over the examined area. A detailed re-processing of this data set and a re-organization into a new digital database were carried out. The re-processing was done using modern adequate techniques, obtaining a remarkable exploitation of the data information content. The result is a colour shaded relief map that shows on a large scale many of the structural lineaments of the Italian area. The inclusion of a larger number of data and the subtraction of an appropriate magnetic reference field are the main reasons of an enhancement in the anomaly definition. This new map replaces the previous Agip version, and aims to become the reference aeromagnetic cartography of the Italian area. We think this work will be useful both for researchers interested in large scale tectonic studies, and for anyone interested in the investigation of smaller scale structures, such as volcanic complexes or infra-sedimentary magnetic bodies, as well as for mining research.

People who attend to the problem of underwater port protection usually use sonar based systems. Recently it has been shown that integrating a sonar system with an auxiliary array of magnetic sensors can improve the effectiveness of the intruder detection system. One of the major issues that arise from the integrated magnetic and acoustic system is the interpretation of the magnetic signals coming from the sensors. In this paper a machine learning approach is explored for the detection of divers or, in general, of underwater magnetic sources that should ultimately support an automatic detection system which currently requires a human online monitoring or an offline signal processing. The research proposed here, by means of a windowing of the signals, uses Support Vector Machines for classification, as tool for the detection problem. Empirical results show the effectiveness of the method.

This paper shows the result obtained during the operative test of an anti-intrusion undersea magnetic system based on a magnetometers’ new self-informed network. The experiment takes place in a geomagnetic space characterized by medium-high environmental noise with a relevant human origin magnetic noise component. The system has two different input signals: the magnetic background field (natural + artificial) and a signal composed by the magnetic background field and the signal due to the target magnetic field. The system uses the first signal as filter for the second one to detect the target magnetic signal. The effectiveness of the procedure is related to the position of the magnetic field observation points (reference devices and sentinel devices). The sentinel devices must obtain correlation in the noise observations and de-correlations in the target signal observations. The system, during four tries of intrusion, has correctly detected all magnetic signals generated by divers.

Summary A shaded relief magnetic anomaly map of total intensity of the Earth’s magnetic field for Italy and the surrounding seas has been produced at sea level, for the geomagnetic epoch 1979.0 (see Chiappini et al., 2000). Magnetic observations were made on shore within the framework of Progetto Finalizzato Geodinamica of the Consiglio Nazionale delle Ricerche (PFG-CNR) between 1977 and 1981. The off shore data were taken during the period 1965-1972 by the Osservatorio Geofisico Sperimentale (OGS). This new compilation gives an unprecedented view of the magnetic anomaly field of the whole area at ground level, which contains many imprints of the major tectonic elements of Italy, and portrays their regional characterization. In 2004 Caratori et al. have undertaken a detailed reprocessing of old aeromagnetic data taken by AGIP at the national scale, with the inclusion of new data. For the first time now the ground level map and the aeromagnetic map show the existence of common features that allow comprehensive correct scientific investigations.

Sviluppo di una stazione portuale per la previsione dei flussi di marea meteorologica, finalizzata a costituire un servizio per la sicurezza della navigazione e per la protezione dei natanti nel Golfo della Spezia.

This paper shows the results of a detailed reprocessing of aeromagnetic data, obtained by the downward projection to the seabed. The area of interest is centered over the Tyrrhenian Basin, whose bathymetric–topographic lay-out is characterized by a somewhat irregular trend. The origin of the intense depth variations depends on the Tyrrhenian structural setting, that is associated with the presence of several tectonic lineaments, seamounts or volcanic islands. The data were characterized by good quality and dense sampling, but they have been reprocessed in order either to solve some problems in the original compilation, and to reduce the distortion of the geomagnetic anomaly field caused by the difference of distance between the survey level and the magnetic source. The reprocessed magnetic map is proposed as an effective analysis tool for the Tyrrhenian area that is characterized by high susceptibility lithotypes. Downward projection of the aeromagnetic data by BTM algorithm increases the definition of the anomalous magnetic signal without distortions in the geometric pattern of the field, thus showing a more stable and effective association between the magnetic anomalies and their geological sources. This effect is particularly true for high frequency anomalies that are directly comparable after the topographic projection because the depth filtering effect is attenuated. Moreover, the BTM method has been applied for the first time to a regional scale survey that shows substantial advantages because no fictitious anomalies in the high frequency sector of the spectrum were generated. This has been a typical effect of the traditional downward projection methods widely used before. The final result is a BTM anomaly map that is able to show the structural connections between the geological magnetic sources of the Tyrrhenian Sea area.

Two main plutonic facies characterize the intrusive complex of the Island of Giglio, and the trend of their contact at depth has been modelled using a 2D½ analysis based on a detailed geomagnetic survey in order to verify the geological hypothesis of the subsurface geometry of this contact. The magnetic anomaly connected with the discontinuity is quite low, due to the small difference between the magnetic susceptibilities of the two granitic facies. Development of this model of inversion of the magnetic field, which is in good agreement with the geological interpretation, was made possible by: 1) accurate control of the geomagnetic time variations and consequent temporal reduction, 2) a very low level of the artificial magnetic noise, 3) high density of the magnetic survey, 4) detailed knowledge of the mapped geologic contact between facies and of their petrologic characteristics, and 5) direct local measurements of the magnetic susceptibilities of the key lithologies. The model shows the trends of the geological contact, as projected in three E-W sections, that dips eastward in the range between 210 and 540, supporting the geologic hypothesis that the Pietrabona facies represents an external shell of the shallowly emplaced Giglio monzogranite intrusion.

An experiment was carried out in the vicinity of the “I Terzi” area in Southeastern Tuscany (fig. 1) to evaluate the applicability of the Time Domain Electromagnetic (TDEM) sounding method under the geological and environmental conditions prevailing in that area. An electromagnetic source was established using a motor-generator set and heavy cable. Measurements were attempted at four sites. Numerous samples of electromagnetic noise were recorded at each of these sites. At one site, signals transmitted for a grounded dipole source at 1.6 km distance were also recorded with the noise. The single set of observations has been processed and inverted to yield a six-layer piecewise constant resistivity depth-profile to a depth of about 2 km. The primary achievement of the experiment was demonstration of the praeticability of TDEM methods under the conditions prevailing in the site.

Some 100 Earth scientists from nine different nations recently gathered in Lerici, Italy; for the Second International Workshop on Geo-Electro-Magnetism. While this was not a thematic meeting, most of the 40 papers presented focused on applications of electromagnetic methods to natural or man-made hazards such as known faults, seismically active regions, volcanoes, landslides, andenvironmental or civil engineering problems. Anomaly and main field studies, both field investigations and theoretical techniques, were also well represented.

1. The phenomenon Abstract Sea level oscillations are the superposition of many contributions, the main ones being astronomic and meteorolog- ical low-frequency tides. In the Ligurian Sea meteo-tide components, being most ample than astronomic fluctuations, drive water exchange in harbours. The present note shows the first results on the port of Genoa concerning a coheren- cy study between atmospheric variation and corresponding sea level adjustment (meteorological tide). The Newton- ian forecasting method of meteorological tides is based on measurements of time elapsing between barometric sea level unbalance (∆g) and its meteorological tide compensation (inverse barometer component). Meteorological tide component is independent of the Earth-Moon-Sun gravitational relationships, and parameters related to the shifted water mass are too many to describe the phenomenon analytically (basin topography, barometric strength position and time, chemical water quality, off-shore sea circulation, etc.). Hence meteorological tide cannot be accurately foreseen by atmospheric pressure measurements only. A gravimeter can detect the geodetic imbalance starting time and a tide-gauge can detect the Newtonian compensation (tide wave) coming time. The difference between these two times is the meteorological tide delay. An opportune statistic of this delay provides an experimental law typical for each harbour to forecast the meteo-tide compensation wave delay. This paper describes the methodological proce- dure adopted and the first evidences of the phenomenon in Genoa harbour.

We describe an inversion method for 3D geomagnetic data based on approximation of the source distribution by means of positive constrained Gaussian functions. In this way, smoothness and positivity are automatically imposed on the source without any subjective input from the user apart from selecting the number of functions to use. The algorithm has been tested with synthetic data in order to resolve sources at very different depths, using data from one measurement plane only.The forward modeling is based on prismatic cell parameterization, but the algebraic nonuniqueness is reduced because a relationship among the cells, expressed by the Gaussian envelope, is assumed to describe the spatial variation of the source distribution.We assume that there is no remanent magnetization and that the magnetic data are produced by induced magnetization only, neglecting any demagnetization effects. The algorithm proceeds by minimization of a χ2misfit function between real and predicted data using a nonlinear Levenberg‐Marquardt iteration scheme, easily implemented on a desktop PC, without any additional regularization. We demonstrate the robustness and utility of the method using synthetic data corrupted by pseudorandom generated noise and a real field data set.

We present here a project for the industrial development of a new magnetometer that is intended to achieve the highest performance in measuring geomagnetic field. The instrument is based on the well-known technology of optically pumped alkali vapour magnetometers. Unlike current commercial models, a diode laser replaces the traditional radio-frequency lamp as pumping source and our magnetometer uses potassium as reference atom, contrary to the more traditional cesium or rubidium. The advantages of this choice are discussed. Preliminary experimental results on a prototype show an expected accuracy better than 1 pT/Hz-1/2.

Magnetic observations made onshore the Italian Peninsula, and across the adjacent seas, have been compiled in a new digital database that provides the first complete regional scale view of the crustal scale magnetic anomalies of the region at sea level. The offshore data were acquired between 1965-1972 by the Osservatorio Geofisico Sperimentale (OGS) while the ground measurements were performed within the framework of the Progetto Finalizzato Geodinamica of the Consiglio Nazionale delle Ricerche (PFG-CNR) between 1977 and 1981. The new shaded relief magnetic anomaly map of total intensity of the Earth's magnetic field for Italy and the surrounding seas has been produced at sea level, for the geomagnetic epoch 1979.0. The most remarkable result of this new map, with respect to the previous compilations and to the aeromagnetic map of Italy, is an unprecedented view of the magnetic signature of the major tectonic elements in their regional setting. There is good correlation between known structural geology and the magnetic anomalies, and now that the longer wavelength signatures have been corrected, deeper interpretations are possible.

The aim of this work is the formulation of a 3D model of the Mt. Amiata volcanic complex (Southern Tuscany) by means of geomagnetic data. This work is shown not only as a real test to check the validity of the inversion algorithm, but also to add information about the structure of the volcanic complex. First, we outline briefly the theory of geomagnetic data inversion and we introduce the approach adopted. Then we show the 3D model of the Amiata volcano built from the inversion, and we compare it with the available geological information. The most important consideration regards the surface distribution of the magnetization that is in good agreement with rock samples from this area. Moreover, the recovered model orientation recall the extension of the lava flows, and as a last proof of validity, the source appears to be contained inside of the topographic contour level. The credibility of the inversion procedure drives the interpretation even for the deepest part of the volcano. The geomagnetic signal appears suppressed at a depth of about 2 km, but the most striking consequence is that sub-vertical structures are found even in different positions from the conduits shown in the geologic sections. The results are thus in good agreement with the information obtained from other data, but showing features that had not been identified, stressing the informative power of the geomagnetic signal when a meaningful inversion algorithm is used.