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The scientific project TESIRA (TEst Site IRpinia fAult), funded in 2021 by the University of Naples “Federico II”, aims at acquiring multidisciplinary geophysical data above an active fault in an intramontane basin of the Southern Apennines and to achieve, through the integration of this multivariate dataset, an accurate 3D geophysical imaging of the shallow structure of the fault zone in order to understand the link between shallow faulting and petrophysical changes, which affect rock permeability and surface degassing. The target structure is the southern branch of the Irpinia Fault, one of the structures with highest seismogenic potential in the Mediterranean region, causing the 4th Italian earthquake of last century (1980, Ms=6.9, Pantosti & Valensise, 1990) and generating a modest surface throw at Pantano San Gregorio Magno (Salerno).A microgravimetric survey and a 3D and 2D Electrical Resistivity measurements survey were acquired between September 2021 and January 2022. 3D seismic data were acquired in July 2022, using two overlapping arrays with a dense geophone distribution covering an area of about four hectares, with a detail of 2.5x2.5m. Moreover, four 2D seismic profiles intersect the 3D volume. An aeromagnetic survey, an extension of the gravimetric survey and a sampling of the CO2 surface degassing will be completed within this year. We will show the preliminary results of the individual surveys. Later, the different geophysical and geochemical measurements will be integrated using cooperative inversion and machine learning techniques. We hope that this multidisciplinary approach will provide a more comprehensive understanding of the interaction between surface faulting and basin development in this key area of the Southern Apennines. ReferencesPantosti, D.; Valensise, G.; [1990] Faulting Mechanism and Complexity of the November 23, 1980, Campania-Lucania Earthquake, Inferred From Surface Observations, JGR, 95, 319-34

Leachate is the main source of pollution in landfills and its negative impacts continue for several years even after landfill closure. In recent years, geophysical methods are recognized as effective tools for providing an imaging of the leachate plume. However, they produce subsurface cross-sections in terms of individual physical quantities, leaving room for ambiguities on interpretation of geophysical models and uncertainties in the definition of contaminated zones. In this work, we propose a machine learning-based approach for mapping leachate contamination through an effective integration of geoelectrical tomographic data. We apply the proposed approach for the characterization of two urban landfills. For both cases, we perform a multivariate analysis on datasets consisting of electrical resistivity, chargeability and normalized chargeability (chargeability-to-resistivity ratio) data extracted from previously inverted model sections. By executing a K-Means cluster analysis, we find that the best partition of the two datasets contains ten and eleven classes, respectively. From such classes and also introducing a distance-based colour code, we get updated cross-sections and provide an easy and less ambiguous identification of the leachate accumulation zones. The latter turn out to be characterized by coordinate values of cluster centroids27 mV/V and 11 mS/m. Our findings, also supported by borehole data for one of the investigation sites, show that the combined use of geophysical imaging and unsupervised machine learning is promising and can yield new perspectives for the characterization of leachate distribution and pollution assessment in landfills.

The detection and imaging of landfills is a challenging task for geophysical methods because major pitfalls may arise, in such complex areas, from the speculative interpretation of geophysical anomalies as geological or antrophic features. In fact, when we face a multi-layered scenario, with numerous resistive to conductive transitions (that is the case of landfills), the actual shape and position of the anomalies (e.g. due to leachate accumulation) can be biased. The use of electrical resistivity tomography (ERT) in combination with the induced-polarization (IP) method, can help in this sense, even though may be not sufficient to completely remove ambiguities in interpretation of inverted models.In this work, we present an application of an unsupervised machine learning k-means algorithm to ERT and IP data acquired in two urban waste disposal sites. The aim of the cluster analysis is to reduce the ambiguity on geophysical model interpretation and to improve the accuracy on detection of anomalous zones related to leachate accumulation. Experimental 2D field data were firstly inverted separately for resistivity and chargeability, using a Gauss-Newton algorithm. Then, joint 2D sections were obtained using k-means clustering of electrical resistivity, chargeability and normalized chargeability (chargeability divided by the resistivity) data. The retrieved model sections provide a quantitative integration of distinct geophysical data, which can offer new perspectives for the characterization of leachate distribution in landfills.

Sediments infilling in intermontane basins in areas with high seismic activity can strongly affect ground-shaking phenomena at the surface. Estimates of thickness and density distribution within these basin infills are crucial for ground motion amplification analysis, especially where demographic growth in human settlements has implied increasing seismic risk. We employed a 3D gravity modeling technique (ITerative RESCaling—ITRESC) to investigate the Fucino Basin (Apennines, central Italy), a half-graben basin in which intense seismic activity has recently occurred. For the first time in this region, a 3D model of the Meso-Cenozoic carbonate basement morphology was retrieved through the inversion of gravity data. Taking advantage of the ITRESC technique, (1) we were able to (1) perform an integration of geophysical and geological data constraints and (2) determine a density contrast function through a data-driven process. Thus, we avoided assuming a priori information. Finally, we provided a model that honored the gravity anomalies field by integrating many different kinds of depth constraints. Our results confirmed evidence from previous studies concerning the overall shape of the basin, however, we also highlighted several local discrepancies, such as: (a) the position of several fault lines, (b) the position of the main depocenter, and (c) the isopach map. We also pointed out the existence of a new, unknown fault, and of new features concerning known faults. All of these elements provided useful contributions to the study of the tectono-sedimentary evolution of the basin, as well as key information for assessing the local site-response effects, in terms of seismic hazards.

We show that high-resolution aeromagnetic surveys, although rarely employed in the research of salt structures, may be an effective and low-cost tool for mapping diapirism. A multiscale analysis of a high-resolution magnetic data set at Nordkapp Basin in the Barents Sea, allows a clear reconstruction of the main salt diapirs of the basin using Multiridge and Compact Depth from Extreme Points methods. We provide a 3-D model of the diapirs extended from 500 to 4,000 m below sea level, characterized by a general low magnetization contrast no larger than −0.08 A/m. The 3-D model is consistent with the salt top depth estimated by 2-D seismics, with borehole data and with the 2-D gravity model of the Uranus diapir. Our imaging shows the capability of the magnetic method that gives new and comprehensive pictures of salt diapirism.

We analyze a wide gravity low in the Campania Active Volcanic Area and interpret it by a large and deep source distribution of partially molten, low-density material from about 8 to 30 km depth. Given the complex spatial-temporal distribution of explosive volcanism in the area, we model the gravity data consistently with several volcanological and petrological constraints. We propose two possible models: one accounts for the coexistence, within the lower/intermediate crust, of large amounts of melts and cumulates besides country rocks. It implies a layered distribution of densities and, thus, a variation with depth of percentages of silicate liquids, cumulates and country rocks. The other reflects a fractal density distribution, based on the scaling exponent estimated from the gravity data. According to this model, the gravity low would be related to a distribution of melt pockets within solid rocks. Both density distributions account for the available volcanological and seismic constraints and can be considered as end-members of possible models compatible with gravity data. Such results agree with the general views about the roots of large areas of ignimbritic volcanism worldwide. Given the prolonged history of magmatism in the Campania area since Pliocene times, we interpret the detected low-density body as a developing batholith.

This paper deals with the Krafla geothermal field, northeastern Iceland, and illustrates how the upgrade of high enthalpy geothermal plants can be effective and lead to increased power production. The aim of this paper is to examine ways of improving the thermodynamic performance of the power plant at Krafla in light of the recent wells. Starting with an energetic and exergetic characterization of the geothermal site, the evolution over time and space was analyzed for the main geothermal parameters and the current energy potential. In light of several newly drilled wells with different characteristics from the previous wells, a number of alternative energy conversion systems are proposed for that installation, analyzing their performances with respect to the current system. The possibility of adding an extra pressure level to the current steam plant was analyzed along with the use of bottoming Organic Rankine Cycles (ORC). For the most promising alternatives, a thorough energy and exergy analysis was carried out including a thermodynamic optimization, in particular identifying a solution that would achieve a significant increase in both total electrical power producible and efficiency. The results are presented in tables and graphs and constitute a useful starting point for a potential reconfiguration for the Krafla power plant.

The Central and Southern Apennines are characterized by the occurrence of intense and widely spread historical and recent seismic activity, mostly located along the chain.In this paper, we present a multi-parametric data analysis in GIS environment (Geographic Information System) with the aim of identifying and constraining the geometry (strike, dip direction and dip angle) of the seismogenic faults in areas of Central-Southern Apennines characterized by outcropping/ buried and/or active/silent faults.We use an integrated analysis of geo-structural, seismological and gravimetric data, for the identification and geometrical description of faults with density contrast, both at the surface and at depth. At the surface, the gravity lineaments inferred by Multiscale Derivative Analysis (MDA) were compared with the Quaternary faults mapped in the study areas and with the earthquakes’ epicentral distribution. The characterization of faults at depth was instead performed by the combination of the Depth from Extreme Points (DEXP) gravity imaging method with hypocentral sections.We tested the effectiveness of this multi-method approach at Mt. Vettore-Mt. Bove, L’Aquila basin, Mt. Massico and San Giuliano di Puglia areas (Central and Southern Apennines).Given the effectiveness of the obtained results, this multiparametric study has been applied to other three areas of the Abruzzo-Molise region: the south-western sector of Mt. Matese, the Fucino basin and the Sulmona basin.The Matese area was hit by a seismic sequence in 2013-2014 (Mwmax= 5.1 on December 29, 2013). Our approach showed a correlation between the epicentral distribution of the 2013-2014 Matese seismic sequence (Mw=5.0) and the MDA lineaments from gravity data. The hypocentral distibution suggests that the fault rupture does not reach the surface. Therefore, the seismogenic fault responsible of 2013-2014 Matese seismic sequence is likely a buried fault.The Fucino basin was struck by a Mw=7.0 earthquake on January 13, 1915, causing 30,000 causalities within a large area surrounding the basin. At present, the area is characterized by scarce instrumental seismicity with low magnitude. Our analysis highlights a good correlation between NW-SE and NE-SW well-known faults and clear gravimetric MDA maxima bordering the plain. This area can be currently considered silent but, from historical seismological studies, it is one the highest seismic risk areas of Central Apennines.Moreover, we investigated the area of the Sulmona basin, the southwards extension of the eastern system of Central Apennines developing from Mt. Vettore, Mt. Gorzano and Mt. Gran Sasso. In historical times, the faults of the most external extensional alignment, defined as silent and considered as probable seismic gaps, activated during the 2016 Amatrice–Visso–Norcia seismic sequence. Further to the southeast, two relatively large earthquakes occurred on the eastern flank of Mt. Maiella on November 3, 1706 (Mw=6.6) and on September 26, 1933 (Mw=5.7). The Sulmona area is presently characterized by poor and low magnitude instrumental seismicity. Our multi-parametric analysis highlighted a strong correlation between MDA maxima and the Mt. Morrone normal fault bordering the western side of Mt. Maiella and the eastern side of the Sulmona basin.

We analyzed new magnetic, bathymetric and seismic data acquired in the offshore sector of Somma-Vesuvius volcano (Italy). We detected a group of high intensity, short wavelength magnetic anomalies corresponding to partly buried volcanic dome-like structures located by seismic data. The magnetic anomalies are aligned along a NW–SE strike that is the preferential orientation of an eruptive fracture of the pre-19 ka activity of Vesuvius. Three cones emplaced before the Last Glacial Maximum, whereas a fourth one emplaced after 19 ka suggesting a rejuvenation of the eruptive system offshore the volcano in historical times. We also identified a NE–SW elongated magnetic anomaly consistent with a dike-like body associated to an on-land tectonic structure that was active in recent times at Vesuvius. A delta-like area with diffuse low intensity magnetic anomalies reflects the seaward fronts of lava flows entered the sea mainly during the Middle Ages.

Our paper shows the preliminary results of a geophysical survey by the Ground Penetrating Radar (GPR) ultradeep "Loza 2N", in the study of buried active faults. This particular and innovative Georadar technique offers several advantages over the classic GPR techniques. Through low frequency antennas (10 MHz), it is possible to carry out deep stratigraphic studies down to about 400 m, thanks to: i) skipping of the stroboscope and cable connections between transmitter and receiver, ii) a direct digitalization of the signal, iii) the use of capacitive coupling Wu-king antennas, iv) a 21 kV (20 Mwatt) transmitter. Furthermore, the latest development of the Loza receiver performed by RTG company allows using time windows up to 512000 nsec, scanning speed up to 1000/sec and stacking up to 100 tracks/sec. These characteristics make the GPR Loza different from most of the other GPR systems that can investigate, under optimal conditions, down to a maximum depth of about 30 m. Through the GPR Loza it is possible to identify, deep stratigraphic contacts and groundwater surfaces, faults and large fracture systems at depth. The Loza interpretative sections of the underground are fully comparable with those deriving from reflection seismics, which on the other hand require costs and acquisition and processing times far larger. In this work, the performances of the instrument are illustrated for identifying the active buried fault system that borders the western edge of the plain "Il Lago" (IS) at the foot of Mount Patalecchia in the Molise Apennines (Southern Italy), an area of high seismotectonic interest. The "Il Lago" plain closes the structure of the Bojano basin towards NW and is bordered by a direct buried fault system. Historically, the area was hit by strong earthquakes: the earthquake of December 5, 1456 (I = XI MCS; Mw = 7.2) which affected central and southern Italy; the earthquake of June 5, 1688 (I = XI MCS, Mw = 7.1) with the epicentral area in the Sannio, and the earthquake of July 26, 1805 (I = X MCS, Mw = 6.7), known as the earthquake of S. Anna whose epicentral area was the Bojano plain.

The choice of an effective interpretative methodology in terms of management costs, timing, reliability, safety and efficiency is a key issue for the identification of unexploded ordnance (UXO). Among geophysical methods, magnetometry plays an important role in detection and interpretation of UXO objects. We present a study aimed at the identification and characterization of buried UXO in Rohoznik, Slovakia, by a multiscale analysis on high-resolution magnetic data. The area is located close to a former army shooting range and is characterized by several buried UXO. When a UXO hits the ground but does not explode, the impact causes a re-organization of the magnetic domains within the armature (shock demagnetization). Due to shock demagnetization the object gets a magnetization oriented in the direction of the actual Earth magnetic field. Furthermore, the elongated shape of the UXO of Rohoznik causes their anomalies to be oriented along the longitudinal axis of the projectiles. Our multiscale analysis was performed through methods such as depth from extreme points (DEXP) and the multi-ridge method. The upward continuation employed by these two methods allowed reducing the influence of the high-frequency noise related to non-UXO buried iron objects. Also, the use of high-order derivatives in the multiscale approach decreased interference effects related to close-by sources and avoided any pre-filtering. Our approach was first validated on a test site located close to Rohoznik, where unexplored projectiles were buried with different orientations at a known depth. Then we focused on the real data of the former army shooting range. For all our analyses we employed a structural index value of 2.5, which was estimated through the scaling function analysis and the derivative euler deconvolution algorithm. Both the (DEXP) and multi-ridge depth-estimation methods proved to be effective and rapid with respect to more expensive and time-consuming methods such as inversion. Our analysis revealed average depths for the analysed UXOs matching rather well with what was found by subsequent excavations, with a maximum discrepancy of a few decimetres.

We report the results of a multidisciplinary investigation performed across the normal Quaternary faults that ruptured the surface during the August 24 (M w 6.0) and October 30 (M w 6.5), 2016 strong earthquakes in the Mt. Vettore-Mt. Bove areas, central Italy. Our aim is to test the effectiveness of the contribution of a multi-scale gravimetric analysis in characterizing seismogenic faults’ geometry at hypocen- tral depths on well-known outcropping faulty systems with known earthquake distribution. We adopted a multi-scale geophysical/geo- logical approach consisting in the comparison of gravity lineaments inferred by Multiscale Derivative Analysis with the Quaternary struc- tural setting mapped in the study area, the primary coseismic surface ruptures of the 2016-2017 sequence and the earthquakes’ epicentral distribution. Moreover, we performed a combined interpretation of 2D hypocentral sections of the 2016-2017 seismic sequences with im- ages resulting from the Depth from Extreme Points method, to infer the faults’ geometry at depth. Based on our results, the investigated NW-SE Mt. Vettore-Mt. Bove fault system is dipping 60°-70° westward. We also detected the splays of this primary fault and its blind an- tithetic NW-SE structure, dipping northeastward. In the Norcia basin we highlight two main faults bordering the basin with a dip of about 45°. The one edging the eastern side dips westward, whereas the fault edging the western side dips eastward. Thanks to our analysis we could identify and characterize the geometry of the Norcia and Vettore master faults, as well as other blind/buried and/or silent faults that are related to the 2016 seismogenic structure. Our results show the effectiveness of this approach in potentially high-hazard areas that are structurally poorly known.

The gravity gradient tensor (GGT) has been increasingly used in practical applications, but the advantages and the disadvantages of the analysis of GGT components versus the analysis of the vertical component of the gravity field are still debated. We analyse the performance of joint inversion of GGT components versus separate inversion of the gravity field alone, or of one tensor component. We perform our analysis by inspection of the Picard Plot, a Singular Value Decomposition tool, and analyse both synthetic data and gradiometer measurements carried out at the Vredefort structure, South Africa.We show that the main factors controlling the reliability of the inversion are algebraic ambiguity (the difference between the number of unknowns and the number of available data points) and signal-to-noise ratio. Provided that algebraic ambiguity is kept low and the noise level is small enough so that a sufficient number of SVD components can be included in the regularized solution, we find that: (i) the choice of tensor components involved in the inversion is not crucial to the overall reliability of the reconstructions; (ii) GGT inversion can yield the same resolution as inversion with a denser distribution of gravity data points, but with the advantage of using fewer measurement stations.

The island of Socorro is located in the eastern Pacific Ocean, 650 km off the coast of Mexico. It is a rare example of an oceanic volcanic island whose above sea level volume is made up mostly of peralkaline trachytes and rhyolites, with subordinate mafic rocks. Subaerial volcanism started several hundred thousand years ago and continues until recent times. We present an investigation of surface and subsurface geology of the island, based on the first detailed extensive geophysical survey on the island. Acquired airborne magnetic and gamma-ray data were compared to existing geological information and supplemented with field investigations and satellite imagery. Magnetic data show a wide minimum in the central part of the island, possibly connected to a high-temperature zone in the deeper central portion of the volcano, likely to be due to a still hot magma body. The data also depict two parallel edges possibly suggesting the existence of a nested caldera. Analysis on upward continued magnetic data by recent imaging techniques highlighted two deep sources located around 5 km b.s.l., interpreted as feeding structures that are now filled with crystalline rocks. Gamma-ray data have been interpreted through integration with the geological survey results. Several previously known volcanic deposits have been identified based on radioelement distribution, and others have been redefined based on field evidence. A new succession of volcanic members is proposed, to be verified through more detailed geological mapping, geochemical analyses of rock samples and radiometric dating.

We present the results of a multidisciplinary and multiscale study at Mt. Massico, Southern Italy. Mt. Massico is a carbonate horst located along the Campanian-Latial margin of the Tyrrhenian basin, bordered by two main NE-SW systems of faults, and by NW-SE and N-S trending faults. Our analysis deals with the modelling of the main NE-SW faults. These faults were capable during Plio-Pleistocene and are still active today, even though with scarce and low-energy seismicity (M-w maximum = 4.8). We inferred the pattern of the fault planes through a combined interpretation of 2-D hypocentral sections, a multiscale analysis of gravity field and geochemical data. This allowed us to characterize the geometry of these faults and infer their large depth extent. This region shows very striking gravimetric signatures, well-known Quaternary faults, moderate seismicity and a localized geothermal fluid rise. Thus, this analysis represents a valid case study for testing the effectiveness of a multidisciplinary approach, and employing it in areas with buried and/or silent faults of potential high hazard, such as in the Apennine chain.

We report the results of a multidisciplinary investigation performed across the normal Quaternary faults that ruptured the surface during the August 24 (Mw 6.0) and October 30 (Mw 6.5), 2016 strong earthquakes in the Mt. Vettore-Mt. Bove areas, central Italy. Our aim is to test the effectiveness of the contribution of a multi-scale gravimetric analysis in characterizing seismogenic faults’ geometry at hypocentral depths on well-known outcropping faulty systems with known earthquake distribution. We adopted a multi-scale geophysical/geological approach consisting in the comparison of gravity lineaments inferred by Multiscale Derivative Analysis with the Quaternary structural setting mapped in the study area, the primary coseismic surface ruptures of the 2016-2017 sequence and the earthquakes’ epicentral distribution. Moreover, we performed a combined interpretation of 2D hypocentral sections of the 2016-2017 seismic sequences with images resulting from the Depth from Extreme Points method, to infer the faults’ geometry at depth. Based on our results, the investigated NW-SE Mt. Vettore-Mt. Bove fault system is dipping 60°-70° westward. We also detected the splays of this primary fault and its blind antithetic NW-SE structure, dipping northeastward. In the Norcia basin we highlight two main faults bordering the basin with a dip of about 45°. The one edging the eastern side dips westward, whereas the fault edging the western side dips eastward. Thanks to our analysis we could identify and characterize the geometry of the Norcia and Vettore master faults, as well as other blind/buried and/or silent faults that are related to the 2016 seismogenic structure. Our results show the effectiveness of this approach in potentially high-hazard areas that are structurally poorly known.

We present the results of a geophysical study at the site of Pian della Tirena, near the town of Nocera Terinese (Calabria, Italy). Geophysical imaging is a recent technique providing a reliable mapping of the three-dimensional magnetization distribution below the ground and, thus, effectively estimating the depth of buried structures. The site studied gained archaeological interest following the hypothesis of the presence of two adjacent, but distinct, settlements. The first one of Hellenic/Hellenistic age (the Temesa of Brettian age), the second (called Tempsa) of Roman age. Even though the site was recently excavated, extensive investigation was not possible due to the broadness of the area and the scarceness of traces at the surface, making it difficult to plan a targeted survey. Two detailed geophysical (magnetic and electromagnetic) surveys were performed in 2006 and 2013 to provide the archaeologists with precise information about the type and position of the buried structures, and increase the efficiency of the investigation. The survey aimed to: (i) confirm and outline the existence of a true urban settlement instead of isolated dwellings; (ii) locate centres of manufacturing activities (local pottery and metal handicrafts); (iii) verify the existence of a boundary wall or road around the settlement. Our three-dimensional analysis and interpretation detected several anomaly trends, most of which show a rather regular shape and orientation. This allowed us to infer the possible existence of a well-developed urban network. The final results provided an archaeological interpretation, building upon the urban network and different use-zones within the town. Copyright © 2015 John Wiley & Sons, Ltd.

We carried out a study of the structures of the volcanic island of Ischia by the analysis and interpretation of high-resolution aeromagnetic data and by a newly compiled in-land gravity data set. The comparison between the vertical gradient of gravity data and pole-reduced magnetic data was performed through semblance analysis and highlighted a correspondence between the main magnetic and gravity highs over the lava and green tuff deposits (e.g., Punta Imperatore, Mt. Trippodi, Zaro, Mt. Rotaro, Mt. Epomeo). Our analysis also highlighted the simultaneous presence of a magnetic minimum and a gravimetric maximum in the central part of the island, mainly visible in the long-period components of the two data sets. This may be due to the existence of a partially demagnetized structure with positive density contrast, representing the island's igneous basement. The boundaries of the lava and tuffs deposits of the island were clearly pointed out by the maxima of the total horizontal gradient maps of magnetic and gravity data. Those maxima also show the position of several lineaments, in good agreement with the mapped faults of the island.

We present a constrained inversion procedure based on a priori information derived exclusively from the analysis on the potential field data themselves (self-constrained inversion). The procedure effectively applies to underdetermined problems and involves scenarios where the source distribution can be assumed to be of some simple character, but perturbations from this simplified body might occur. To set up effective constraints we first estimate by an analysis of the gravity or magnetic field some or all of the following source parameters: the source depth-to-the-top, the structural index, the horizontal position of the source body edges and their dip. The second step is incorporating the information related to these constraints in the objective function as depth and spatial weighting functions. We show, through some 2D and 3D synthetic and real data examples, that the sole potential field-based constraints are most of times enough to obtain rather good improvements in the density and magnetization models.

Starting with the tragic case of the earthquake in L'Aquila this paper discusses a fundamental aspect of the correct evaluation of the danger (hazard) of an area and of a specific urban site, that is, the underestimation of the amplyfying effect of the sites in many developed Italian urgan areas situated in valleys or alluvial plains along with a scarce or incomplete knowledge of the geoseismic parameters of the local underground area.

In past decades, magnetic surveying had become popular as one of the most effective techniques supporting archaeological prospecting. This is possible because the existence of susceptibility contrasts between the cover soil and several buried finds often causes detectable anomalies. More recently, great advances were made in signal enhancement and boundary analysis of potential field anomalies, thanks to methods allowing a suitable differentiation of the field without making the process unstable. New three-dimensional (3D) imaging techniques provided an estimate of the magnetization distribution within the subsoil by means of high-resolution images of the source distribution. Most of these methods are fast and reliable in the presence of shallow and compact sources, just as in the case of the sources usually occurring in archaeological prospecting. Nevertheless, great effort was spent by the scientific community to overcome serious problems causing low signal-to-noise ratio in the measurements. This chapter provides a step-by-step description of technical solutions adopted to improve the quality of data and to perform a better interpretation of the magnetic anomalies usually associated to the presence of archaeological finds. To this end, a summary of case histories is illustrated giving a general framework of the latest progress in archaeo-magnetism.

In this paper we give an overview of the recent geophysical, geochemical and volcanological studies concerning the island of Ischia within the geological and tectonic framework of Southern Italy. Ischia is an active volcanic field that had a complex volcanic history resulting from dominant explosive and minor effusive activity, several caldera collapses, and renewed volcanism from vents located inside the collapsed area. The island is morphologically dominated by Mt. Epomeo, the result of a prominent resurgence phenomenon taking place since ca. 33 ka BP, and responsible for ca. 900 m of total uplift, one of the largest known compared to the relatively small size of the caldera. The uplift was accompanied by activation of faults, seismic activity and renewal of volcanism, and may be considered a main factor for inducing slope instability. For Ischia, volcanological, petrological and geophysical studies are, at present, limited compared to the other active volcanoes of the Neapolitan Area. Furthermore, the island is characterized by high volcanic, seismic and hydrogeological risks. Thus, this review is aimed at highlighting aspects of the knowledge on Ischia that need more investigations, in order to better assess some characteristics of its structural setting. Features such as the precise location of the caldera boundaries and the depth of the magma chamber representing the drive for the resurgence still need to be well defined. A critical analysis of all lines of evidence relevant to the current theories about the island resurgence ( resurgent block vs. resurgent dome ) has been carried out. Our analysis reveals that the resurgent block model, differently from the resurgent dome model, is consistent with the most significant features, such as tilting of the resurgent block, faults type, dip and distribution at the edges of the block, and occurrence of most of the past 10 ka eruption vents on the eastern sector of the island. However, as both model require an input of fresh magma into the shallow plumbing system, it is not clear at present how much magma was necessary to achieve the measured uplift, and whether the drive was provided by magma or magmatic volatiles.

In this paper we present an approach for evaluating landslide susceptibility in seismic areas. It is known that earthquake-induced landslide susceptibility is related to several, often interplaying, factors. Nevertheless, an effective grade-2 zonation should be characterized by a good balance between simplicity, quickness and reliability. The GIS-based procedure we present employs only three factors that we believe are the most significant in this susceptibility assessment: the type of outcropping rocks/soils, the slope angle and the MCS intensity. The local annual precipitation, certainly an essential factor, is considered here as a parameter whose seasonal pattern is constant in time and space. Each of the three parameters is expressed as a Significance percentage and the resulting Seismic Landslide Susceptibility level of an area is given by the average of the significances of the first two factors multiplied by the significance of the third factor. The procedure was set and tested on the volcanic island of Ischia (southern Italy), which was affected by several historical earthquake-induced landslides. The results of this susceptibility zonation test at Ischia show a very good match between the distribution of the sources of historical landslides and the areas we identified as the most susceptible ones.

We study the inversion of potential fields and evaluate the degree of depth resolution achievable for a given problem. To this end, we introduce a powerful new tool: the depth-resolution plot (DRP). The DRP allows a theoretical study of how much the depth resolution in a potential-field inversion is influenced by the way the problem is discretized and regularized. The DRP also allows a careful study of the influence of various kinds of ambiguities, such as those from data errors or of a purely algebraic nature. The achievable depth resolution is related to the given discretization, regularization, and data noise level. We compute DRP by means of singular-value decomposition (SVD) or its generalization (GSVD), depending on the particular regularization method chosen. To illustrate the use of the DRP, we assume a source volume of specified depth and horizontal extent in which the solution is piecewise constant within a 3D grid of blocks. We consider various linear regularization terms in a Tikhonov (damped least-squares) formulation, some based on using higher-order derivatives in the objective function. DRPs are illustrated for both synthetic and real data. Our analysis shows that if the algebraic ambiguity is not too large and a suitable smoothing norm is used, some depth resolution can be obtained without resorting to any subjective choice of depth weighting.

We describe a multihomogeneity theory for source-parameter estimation of potential fields. Similar to what happens for random source models, where the monofractal scaling-law has been generalized into a multifractal law, we propose to generalize the homogeneity law into a multihomogeneity law. This allows a theoretically correct approach to study real-world potential fields, which are inhomogeneous and so do not show scale invariance, except in the asymptotic regions (very near to or very far from their sources). Since the scaling properties of inhomogeneous fields change with the scale of observation, we show that they may be better studied at a set of scales than at a single scale and that a multihomogeneous model is needed to explain its complex scaling behaviour. In order to performthis task,we first introduce fractional-degree homogeneous fields, to show that: (i) homogeneous potential fields may have fractional or integer degree; (ii) the source-distributions for a fractional-degree are not confined in a bounded region, similarly to some integer-degree models, such as the infinite line mass and (iii) differently from the integer-degree case, the fractional-degree source distributions are no longer uniformdensity functions. Using this enlarged set of homogeneous fields, real-world anomaly fields are studied at different scales, by a simple search, at any local window W, for the best homogeneous field of either integer or fractional-degree, this yielding a multiscale set of local homogeneity-degrees and depth estimations which we call multihomogeneous model. It is so defined a new technique of source parameter estimation (Multi-HOmogeneity Depth Estimation, MHODE), permitting retrieval of the source parameters of complex sources. We test the method with inhomogeneous fields of finite sources, such as faults or cylinders, and showits effectiveness also in a real-case example. These applications showthe usefulness of the new concepts, multihomogeneity and fractional homogeneity-degree, to obtain valid estimates of the source parameters in a consistent theoretical framework, so overcoming the limitations imposed by global-homogeneity to widespread methods, such as Euler deconvolution.

In potential-field inversion, careful management of singular value decomposition components is crucial for obtaining information about the source distribution with respect to depth. In principle, the depth-resolution plot provides a convenient visual tool for this analysis, but its computational complexity has hitherto prevented application to large-scale problems. To analyze depth resolution in such problems, we developed a variant ApproxDRP, which is based on an iterative algorithm and therefore suited for large-scale problems because we avoid matrix factorizations and the associated demands on memory and computing time. We used the ApproxDRP to study retrievable depth resolution in inversion of the gravity field of the Neapolitan Volcanic Area. Our main contribution is the combined use of the Lanczos bidiagonalization algorithm, established in the scientific computing community, and the depth-resolution plot defined in the geoscience community.

In this paper we describe the application of GPR and resistivity (dipole-dipole) methods to an archeological investigation. The aim of this study was to obtain information about buried pre-Roman structures below the Roman residence “Casa dell’Atrio a Mosaico,” in the ancient town of Ercolano (Naples). A number of resistivity (dipole-dipole) and GPR profiles were carried out on the mosaic floor of the house. To perform resistivity profiles in a nondestructive way on the mosaic floor, special flat-base copper electrodes were used. The electrode spacing used was [Formula: see text] and [Formula: see text]. GPR data were collected using [Formula: see text] and [Formula: see text] antennas. The radar profiles were carried out primarily along the electrical profiles in order to obtain a direct comparison between the two methods. Both resistivity and GPR methods evidenced a number of structures buried at shallow depths. Both methods located a structure identified as a conductive body with electric parameters strongly contrasting those of the surrounding material. The archaeological interpretation of such structures is in terms of remnants of walls of pre-Roman houses and of a cistern used for collecting rain, connected to a pipe.

A careful management of the data errors in potential field inversion is crucial for obtaining reliable information about the source distribution with respect to depth. The Depth Resolution Plot introduced by Fedi, Hansen and Paoletti provides a convenient tool for this analysis: it allows a computational/visual analysis of how much the depth resolution in a potential-field inversion problem is influenced by the way the problem is discretized and regularized. Here we present a variant of the Depth Resolution Plot, called Approx Depth Resolution Plot, which is better suited for large-scale problems, and we employ it to study the retrievable depth resolution in the inversion of the gravity field of the Neapolitan Volcanic Area.

Many methods have been used to upward continue potential field data. Most techniques employ the Fast Fourier transform, which is an accurate, quick way to compute level-to-level upward continuation or spatially varying scale filters for level-to-draped surfaces. We here propose a new continuation approach based on the minimum-length solution of the inverse potential field problem, which we call Volume Continuation (VOCO). For real data the VOCO is obtained as the regularized solution to the Tikhonov problem. We tested our method on several synthetic examples involving all types of upward continuation and downward continuation (level-to-level, level-to-draped, draped-to-level, draped-to-draped). We also employed the technique to upward continue to a constant height (2500 m a.s.l.), the high-resolution draped aeromagnetic data of the Ischia Island in Southern Italy. We found that, on the average, they are consistent with the aeromagnetic regional data measured at the same altitude. The main feature of our method is that it does not only provide continued data over a specified surface, but it yields a volume of upward continuation. For example, the continued data refers to a volume and thus, any surface may be easily picked up within the volume to get upward continuation to different surfaces. This approach, based on inversion of the measured data, tends to be especially advantageous over the classical techniques when dealing with draped-to-level upward continuation. It is also useful to obtain a more stable downward continuation and to continue noisy data. The inversion procedure involved in the method implies moderate computational costs, which are well compensated by getting a 3D set of upward continued data to achieve high quality results.

We processed and interpreted a newly acquired geophysical dataset (WS10 project) integrated with vintage seismic profiles to study the evolution of the Sardinian passive margin of the Sardo-Provencal basin. The most prominent features of the area of study are a consequence of the Messinian Salinity Crisis (MSC) which produced a thick salt layer in the deep basin. Complex halokinetic tectonics deformed the overlying Messinian Upper Unit (UU) and the Pliocene–Quaternary (PQ) sediments, sometimes also bending the sea bottom. A thinner autochthonous salt in the UU suggests at least one further low stand during the late MSC. The Messinian Erosional Surface (MES) separates the erosional truncation of the pre-Messinian sedimentary sequence from the overlaying Plio-Pleistocene sequence with a clear angular discordance, which almost completely masks possible earlier erosional events. The MES is present across the middle and upper slopes of the Sardinian margin and can be easily recognized down to the lower slope, where it interfingers with the Messinian evaporites which gradually thicken basinward. We propose a correlation between the main erosional surface of the lower slope and the salt layer recognized in the UU as a consequence of a falling stage during the last part of the MSC. The seismic profiles now available along the West Sardinian margin provide novel and crucial information to correlate the Messinian depositional units in the deep basin with those present in the lower continental slope and with the erosional surface of the middle and upper slopes. Our data and interpretation highlight the main units of the Messinian trilogy and further internal sequences that are probable related to cyclic fluctuations during their deposition.

The main objective of the present study is to evaluate seismic attenuation relationships for the Campanian area (southern Italy) using the felt intensity report data obtained from comprehensive historical databases (DOM 4.1). We focused our attention on the Campania region because it is characterized by a high seismic hazard and risk, particularly in the Naples area and its suburbs. In order to derive an attenuation relationship for the area, we fitted the observed data by using several functions. We found that a linear plus logarithmic model gives the best fits for the data in the Campanian region. Most of the attenuation relationships proposed up to now for the Italian Peninsula have an isotropic behavior and do not always properly describe the macroseismic attenuation. Therefore, in order to check the possible dependence of the attenuation on the azimuth of the seismic rays, we divided our data set in octants and performed for each of them the same analysis we carried out for the whole data set. The obtained results differ from octant to octant and the differences, besides being associated with the source effects, could be interpreted as probably due to the existence of lateral variations in the lithological and physical features of the crust at different depths, which could affect the patterns of attenuation.

In this paper we recall a method for medium scale (level-2) zoning of seismic-induced landslide susceptibility and present its application to the Sannio-Irpinia area, Southern Italy. Previous small scale studies of the entire Campania Region identified this area as one of the most susceptible to earthquake-induced landslides in the region. The area's intense seismic and landslide activity and the characteristics of the deposits involved in landslides make this analysis an interesting case study for land planning, management and protection of an area characterized by high seismic and hydrogeological hazard. The result of the zoning shows good agreement between the distribution of the historical earthquake-triggered landslides and the areas defined by the method as the most susceptible ones. They also highlight the method's effectiveness in the presence of complex clayey deposits. (C) 2013 Elsevier Ltd. All rights reserved.

In this paper, we present a GIS-based method for regional zoning of seismic-induced landslide susceptibility and show its application to the territory of the Campania region, Southern Italy. The method employs only three factors that we believe are most significant in the susceptibility assessment: the type of outcropping rock/soil, the slope angle, and the MCS intensity. Each of the three parameters is quantified in terms of relative weight expressed as indices, and the resulting Seismic Landslide Susceptibility index of an area is given by the average of the indices of the first two factors multiplied by the index of the third factor. The result of this susceptibility zonation applied to Campania shows a good agreement between the distribution of the historical earthquake-triggered landslides and the highly susceptible zones.

Summary We describe a multiscale method for source parameter estimations (depth to the source, homogeneity degree) based on a new theory, which we propose for studying explicitly inhomogeneous field. The theory consists in enlarging the set of homogeneous fields with those having a fractional homogeneity-degree and in relaxing the standard homogeneous equation to a local homogeneity equation. We show the validity of the method as applied to the inhomogeneous-degree gravity fields of a finite vertical cylinder.

In this paper we present and analyze the new detailed aeromagnetic data set resulting from a recent survey car- ried out in the Phlegrean Fields volcanic area. The survey was aimed at gaining new insight into the vol- canological characteristics of the region north of Phlegrean Fields (Parete-Villa Literno area) where remarkable thickness of volcanic/sub-volcanic rocks were found in wells. Measurement of total magnetic field was per- formed on two different flight levels, 70 m and 400 m above the ground surface, along flight lines spaced 400 m apart. Both aeromagnetic maps show the noisy effect of linear anomalies evidently due to the presence of rail- way lines. To filter out these local anomalies a method based on discrete wavelet transform was used, allowing an accurate local filtering and leaving the rest of the field practically unchanged. The filtered data set was inte- grated with the existing Agip aeromagnetic map of the Phlegrean Fields, leading to a new aeromagnetic map of the whole Phlegrean volcanic area. The compilation of the pole reduced map and of the maps of the Analytic Signal and of the Horizontal Derivative of the integrated data set represents a first step for the interpretation of the maps in terms of geological structures of the whole Phlegrean volcanic district.

Since the Sixties, the turning point marked by the Plate Tectonics global theory has provided new ideas for the interpretation of the complex geodynamic evolution of the Mediterranean area. The renewed interest that followed gave a strong impulse to the geological and geophysical investigations of the Mediterranean area and, more specifically, of the Tyrrhenian Basin. Therefore, large scale geophysical surveys and oceanographic cruises were carried out until the end of the Eighties to fill the gap of geophysical information existing in the area until then. Afterwards, short scale surveys were prevalent to improve the detail of the information in areas of geodynamic interest. The gathered data sets allowed new models to be formulated, improving the knowledge of the crustal and lithospheric structure of the Tyrrhenian Basin (and surrounding areas) and the reconstruction of its complex geodynamic evolution. In this frame, the contribution of gravity and magnetic investigations has been unquestionable and deserves a wide-ranging review both on large and small scale. The main features of the potential fields resulting from these surveys will be described and the interpretative models suggested by several authors will be summarized.

In this paper we present a study of the structural setting of the volcanic island of Ischia by the analysis and interpretation of high-resolution aeromagnetic and self-potential data recently acquired over the island. The magnetic data allowed us to locate the main anomaly sources and lineaments of the island and its offshore surroundings, while the self-potential (SP) data provided information on both the structural pattern of the resurgent caldera and the high-temperature fluid circulation. An inversion of the acquired magnetic and SP data, and a joint modelling of the magnetic data and of a previous gravity data set along a SW–NE profile allowed us to build a model of the island. The model is characterized by the presence of an igneous–very likely trachytic–structure, whose top is located at 1200–1750 m b.s.l. Such a body, possibly formed by several neighbouring intrusions, has a density contrast with the pyroclastic cover of about 0.4 gr/cm 3 and its central-western part, below Mt. Epomeo, seems to be demagnetized. The demagnetization should be connected to the high geothermal gradient measured in this portion of the island and may be due to hydro-chemical alteration processes and/or to the possible presence of partially melted spots within the intrusion. Our outcome is consistent with the results of previous geophysical, geo-volcanological and geothermal studies.

This paper presents a study of the Phlegrean Fields-Ischia submarine ridge by the analysis and interpretation of high-resolution aeromagnetic data recently acquired in the Western Procida offshore. The investigated area is located along the ridge connecting Ischia to the Phlegrean Fields and is characterized by the existence of several monogenetic volcanoes aligned on a NE-SW system of faults. The high-resolution magnetic data yielded new information on the area, highlighting particularly the signature of a volcanic body located between Pt. Serra and the Ruommoli shoal. This structure has not been clearly described before and we named it as the Pt. Serra submarine volcano. The computation of the analytic signal and horizontal gradient of the data distinctly located this structure and definined the position of its rims. A 2D modeling and 3D inversion of data provided information on the volcanos thickness, width and magnetization, disclosing a meaningful igneous body extending down to several hundred meters b.s.l.

La pericolosità sismica : dalla classificazione sismica alla microzonazione dei territori comunali, alla risposta sismica del sito (con particolare attenzione alla Campania)