Inspection of architectural structures with integrated electrical methodologies and infrared thermography

B030 INSPECTION OF ARCHITECTURAL STRUCTURES WITH INTEGRATED ELECTRICAL METHODOLOGIES AND INFRARED THERMOGRAPHY Abstract 1 The attention of this paper was focused on the detection of moisture and local inhomogeneities inside architectural structures with electrical methodologies and infrared thermography. To this end a suitable specimen was fabricated using a mixture of sand water and concrete and with slag inclusions. To monitor the moisture variation with time in concrete nondestructive evaluation with both the techniques was made three months after the specimen fabrication and repeated again six months later. Introduction The inspection of architectural structures generally includes vario…

La sicurezza nell'identità dei beni culturali in materiali lapidei: la firma sonica

TECNICHE NON INVASIVE DI SUPERFICIE E DI VOLUME PER IL MONITORAGGIO STRUTTURALE DELLE SCULTURE MARMOREE

L’analisi delle proprietà strutturali di una scultura in marmo, attraverso l’impiego di tecniche di indagine non invasive da realizzare direttamente in situ, è di fondamentale importanza per la valutazione dello stato di conservazione e, conseguentemente, per il monitoraggio di eventuali fenomeni di degrado che possono compromettere l’integrità dell’opera d’arte. Lo studio condotto sul bassorilievo raffigurante la Madonna con Bambino conservato presso la Cappella del Monastero delle Clarisse Totus Tuus di Gorizia ha permesso di verificare la complementarietà delle informazioni restituite da tecniche di analisi della superficie (acquisizioni in fluorescenza ultravioletta) e tecniche di anali…

ERT and IPT surveys to check the integrity of the geomembrane in the landfill of Bellolampo (Palermo, Italy)

In landfills, changes in resistivity and chargeability can be related to the characteristics of the waste and they can be abrupt and considerable within short distances. These physical properties are function of generation, mobility and degree of saturation of the leachate, gas generation, compaction density and variability. These relationships mean that it can be possible to get an overall image of the quantity and characteristics of the waste from surface electrical measurements over the landfill. In this paper, we present and discuss the results of three electrical tomographies carried out in the landfill site of Bellolampo (Palermo, Italy). The main aim of these surveys was to check the…

Influence of different array datasets on reliability of electrical resistivity tomography

The goal of this work is to study how the reliability of inverse model depends on a few basic parameters, as the combination of potential spacing and dipolar distance and, consequently, the number of measurements and of current dipoles, considering also how error affects inversion. The number of current dipole used is crucial, when using multichannel resistivity-meters, because it determines the overall acquisition time. A systematic comparison is presented between four 2D resistivity models and their images, obtained by the inversion of synthetic datasets relating to four different arrays: dipole-dipole (DD), pole-dipole (PD), Wenner-Schlumberger (WS) and multiple gradient (MG). For DD, PD…

Evidence of surface faulting in the archaeological site of Santa Venera al Pozzo (Catania-Eastern Sici-ly): first results from geophysical investigations

We present the first results of a preliminary geological and geophysical survey carried out in the archaeological site of Santa Venera al Pozzo (Catania, Italy). The site dates back to the Roman Age, (1st century BC). Geological surveys highlighted a set of remarkable fractures affecting some archeological remains, suggesting the occurrence of a capable fault zone through the area. Multidisciplinary geophysical surveys (seismic refraction and electrical resistivity tomographies, together with aerial photographic and thermographic survey) identified a main tectonic discontinuity ascribable to the fault zone, allowing us to infer that the fractures observed at surface could be the evidence of…

An Overview of Geophysical Techniques and Their Potential Suitability for Archaeological Studies

The need to study, protect, and conserve archaeological heritage has enhanced the application of geophysical techniques as non-invasive and reliable tools to investigate fragile and valuable assets. This review presents the most popular geophysical techniques suitable for archaeogeophysical investigations, namely, magnetometry, ground penetrating radar, and electrical resistivity tomography, together with a series of multiparametric measures taken from aerial platforms (UAS). For each method, we recall the basic physical principles, illustrate the operative procedures for field investigation, and provide indications about data processing and modeling. We propose a flowchart to address relia…

Cluster analysis to support microzonation studies

In recent times the use of microtremor techniques for subsoil investigation increased significantly. The use of HVSR (Horizontal to Vertical Spectral Ratio)technique for seismic microzoning studies allows in many case to obtain detailed reconstruction of the roof of the seismic bedrock and to identify areas with similar seismic behaviour. Two different algorithms of clusteringhave been tested on a HVSR datasets acquired for studies of seismic microzoning in various Sicilian urban centers. HVSR data were previously properly processed to extract frequency and amplitude of peaks by a code based on clustering of HVSR curves determined in sliding time windows.To select an optimal set of time win…

Contributo geofisico per la ricostruzione di cavità di interesse storico nel sottosuolo di Palermo

Some tests of 3D ultrasonic traveltime tomography on the Eleonora d'Aragona statue (F. Laurana, 1468)

Abstract The use of a non-destructive technique in situ can be a valuable diagnostic tool to support verification of restoration, as well as a monitoring technique in works of art or historical monuments. We present a high resolution 3D ultrasonic tomography to one of the most important statues of the Regional Gallery of Palazzo Abatellis of Palermo, the bust of Eleonora d'Aragona by F. Laurana (1430–1502). This technique allowed to study the structural continuity of the material of the marble. Some tests have been carried out to optimize inversion parameters, such as voxel size and to choose between straight and curved rays. We propose to calculate a minimum lateral resolution using the sa…

Ricerche Geofisiche di resti archeologici sotto la cattedrale di Tarragona (Spagna): Tomografia Geoelettrica (2d E Full-3d) e Gpr

Integrated hydrogeochemical and geophysical surveys for a study of sea-water intrusion

The CFTA Department of the University of Palermo in collaboration with ARPA SICILIA has carried out a study of the sea intrusion phenomenon in the aquifer between the cities of Marsala and Mazara del Vallo (south-western Sicily) using geophysical techniques (TDEM, ERT and MASW) and geochemical analysis of well water. The aim of the research was to optimize the acquisition techniques, data processing and data interpretation for the geometry reconstruction of aquifers, their characterization, and the determination of concentration of pollutants. The analysis of the geophysical results reveals the existence of very low resistivity values in correspondence of the area from the coastline to a ki…

Integrated geophysical surveys in the tarragona cathedral

An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to detect the existence of archaeological remains of the Roman’s temple devoted to August. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most famous temple of Spain (12th century) evolving from Romanesque to Gothic styles. A project including electrical resistivity tomography (ERT), ground probing radar (GPR) and frequency domain electromagnetics (FDEM) has been planned over one year and conducted during a week of intensive field survey. From all the methods applied, both ERT and GPR…

The Sonic Imprint to identify and monitor precious artefacts: further developments

A new non-invasive technique, developed to univocally identify and monitor the integrity of precious artefacts, like potteries, statues and objects, generally made of stone, metal or wood, has been already presented (2). This technique responds to the demand, especially felt among museum managers, of an art collection cataloguing which allows the identification of artefacts and the assessment of their physical conditions. This is also linked to the international loan of precious artefacts, which are then subjected to transport stresses and to the connected risks (damages, substitutions, physical deterioration, etc.). Furthermore, in these days many art exhibitions are itinerant, and the art…

INVERSION TESTS ON ULTRASONIC TOMOGRAPHY DATA

3D Ultrasonic Tomography for non-destructive test and for diagnostic study works of art is a rather established methodology. This method allow us to locate, within the volume of work of art, areas of structural non homogeneities, areas of decay, fracture or damaged. This work wants to present some tests carried out to optimize these parameters in order to obtain a better anomaly image resolution for the case history presented. The optimization of these parameters allows locating structural non homogeneity areas, fractures or damages, within the volume, according to shape and type of the investigated anomalies.

Improvement of HVSR technique by cluster analysis

The Horizontal to Vertical Spectral Ratio (HVSR) technique, applied to ambient noise, is widely used to quickly estimate the fundamental frequency of a site. The HVSR technique is based on numerous assumptions about the propagation medium and the nature of the seismic noise, often hard to verified. In addition, in order to obtain reliable results, several acquisition and processing criteria must be respected. One of the most controversial aspects in the technique implementation are the reliable criteria for the identification in the microtremors signals of time windows appropriate for the calculation of the HVSR curves. Several authors suggest to remove spikes and transients because they br…

Centroid-based Cluster Analysis of HVSR Data for Seismic Microzonation

Horizontal to Vertical Spectral Ratio (HVSR) datasets acquired for studies of seismic microzoning in various urban centers of Sicilian towns, have been used to test clustering analysis through a nonhierarchical centroid-based algorithm. In this context clustering techniques may be useful to identify areas with similar seismic behaviour through HVSR data. Centroid-based algorithms generally require the number of clusters, k, and the initial centroid coordinates to be specified in advance. This aspect is considered to be one of the biggest drawbacks of these algorithms. The proposed algorithm doesn’t limit the number of k clusters and choose the initial centroids automatically from the data s…

Tomografia Sonica ed Ultrasonica per il supporto all’intervento di restauro della statua del togato di Petrara (I Sec. D.C.)

Nel 2003, a Locri (RC), è stata ritrovata la statua-ritratto in marmo del c.d. “togato di Petrara” (I sec. d.C.), rappresentata in Fig. 1, come si presenta dopo il restauro. Si tratta, probabilmente di una statua onoraria di un magistrato del municipium locrese, alta circa m 2,16 ma spezzata in tre parti: piedi con basetta, testa e figura. Dal marzo al luglio 2008 sono state eseguite le operazioni di restauro del manufatto per ricomporre la statua e porla nuovamente in posizione eretta. Una notevole lesione, infatti, era visibile sul fianco sinistro e sul retro. La causa di tale lesione si individuava subito con la presenza di un grosso perno a sezione quadrata inserito già in antico per il…

A Fast Imaging Technique Applied to 2D Electrical Resistivity Data

A new technique is proposed to process 2D apparent resistivity datasets, in order to obtain a fast and contrasted resistivity image, useful for a rapid data check in field or as a starting model to constrain the inversion procedure. In the past some modifications to the back-projection algorithm, as well as the use of filtering techniques for the sensitivity matrix were proposed. An implementation of this technique is proposed here, considering a two-step approach. Initially a damped least squares solution is obtained after a full matrix inversion of the linearized geoelectrical problem. Furthermore, on the basis of the results, a subsequent filtering algorithm is applied to the Jacobian ma…

The integration of surface and subsurface stratigraphic data with HVSR measures for studies of seismic microzonation: the case of Oliveri (ME)

Because of its high seismic hazard the urban area of Oliveri has been subject of a study on seismic microzonation at first level (OPCM 3907/2010). The urban area develops on a large coastal plain made of Late Pleistocene and Holocene mixed fluvial/marine sediments, that mainly consist of silty sands and gravels. The eastern part of this plain is dominated by the alluvial deposits of the Elicona torrent. The coastal and alluvial sediments overlap a complexly deformed substrate made of Hercynian metamorphites (Aspromonte unit), the Capo d’Orlando Flysch, the Antisicilide Argille Scagliose and Pleistocene clays and calcarenites. This area is affected by high uplift rates as recently estimated …

Seismic tomography tests applied to a gravity dam

The control of the safety assessment of a dam is largely dependent on knowledge of the mechanical parameters of the actual construction, as well as its geological substratum. The application of geophysical methods can be used in existing dams to evaluate the materials (strength properties) and to verify if they match design expectations, as well as to contribute to the safety control. In particular seismics methods can considerably contribute to the examination indicating the less consolidated material and the degradation of mechanical parameters. For the characterization of the concrete conservation three seismic tomographies and a vertical seismic profile on the dam body were performed.Th…

Microgeofisica per lo studio dei beni culturali movimentabili

Diagnostica per il consolidamento del mosaico pavimentale dell'ambulacro nella Villa Romana dal Casale (Piazza Armerina)

Seismic Characterization by Inversion of HVSR Data to Improve Geological Modelling

SUMMARY An application of HVSR inversion is presented in order to verify the effectiveness of this technique for purposes of geological reconstruction of the subsoil finalized to studies of seismic microzonation of heavily urbanized areas, where few stratigraphic and geophysical constraints are available and most of the information are derived from the geological maps. In such cases the uncertainty of the results is is enhanced by doubts on the nature of the H/V peaks, not always caused by stratigraphic discontinuities, and to the subjective choices done especially in the step of signal preprocessing. The investigated area (Altavilla Milicia, Sicily) includes the town center and the adjacen…

Geomorphological and geophysical investigations to study the landslide affecting the archaeological site of abakainon

In recent years, a detailed archeoseismological investigation has been carried out in the necropolis of Abakainon in order to identify traces of an ancient earthquake. Although the identification of seismic damage was undoubtedly attributed to the 1st century AD earthquake, it was hypothesised that the level of damaging observed in the necropolis, as well as the counter slope tilting of the tomb basements may have also caused by a seismo-induced landslide, which produced locally an amplification of the seismic shaking. In order to identify the landslide, on which the Greek site lies, detailed geomorphological and geophysical surveys have been carried out. The research was directed to the ac…

Studi di base per il monitoraggio elettrotomografico dell’intrusione salina dell’acquifero di Petrosino

Indagini nell'area ad ovest del Tempio della Vittoria ad Himera

Himera: New investigations in the area West of the Tempio della Vittoria · The University of Palermo has started a new cycle of field investigations in the “lower town” of Himera, with the aim of answering some questions about the relationships between the Tempio della Vittoria, the residential districts, and the agora, that remained to be clarified after the important results produced by the studies on the urban development of the Greek city over the past forty years. This paper presents some initial results and research perspectives from the first excavation soundings and geophysical survey of 2021. The first findings strongly suggest that the agora extended much further south than previo…

LA TOMOGRAFIA AD ULTRASUONI PER LO STUDIO DIAGNOSTICO DEI BENI CULTURALI

La Tomografia Ultrasonica 3D ad alta risoluzione è una tecnica relativamente consolidata nello studio diagnostico non invasivo di opere d’arte. L’analisi tomografica può essere eseguita con elaborazioni dei segnali finalizzate a ricostruzioni cinematiche e/o con analisi dei segnali finalizzate a ricostruzioni di assorbimento energetico. Le prime sono, per vari aspetti, molto più semplici da eseguire e sono di gran lunga le più diffuse. L’utilizzazione corretta di questa tecnica trova un punto di criticità nella scelta dei parametri (geometrici, fisici, tecnologici, modellistici) utili per l’acquisizione, l’elaborazione e l’inversione dei dati sperimentali, da selezionare in funzione della t…

Integrated full 3D geoelectrical and GPR tomographies in the Ambulatory of the roman “Villa del Casale”(Piazza Armerina)

The “Villa del Casale” is a wonderful Roman Villa excavated in the archaeological site of Piazza Armerina (Sicily) in 1929. Its interest is mainly to be referred to the floor mosaics, among the largest and most beautiful ones of Roman times, of superlative quality. The floor of the Corridor is covered by a wonderful mosaic depicting the hunt and capture of wild animals, so that it is called the “Corridor of the Great Hunting Scene”. The Villa is now under restoration, and during the planning of the restoration a 3D electrical resistivity tomography was performed on the corridor by using an acquisition grid composed by 704 electrodes. Furthermore 25 GPR profiles with 400 MHz antenna were acq…

New seismological, structural and marine geology constraints for a seismotectonic model of the hinge zone between northern Sicily and southern Tyrrhenian

New ultraportable data logger to perform magnetic surveys

This article presents the realization of a device for magnetic surveys It is a flexible, user-reprogramable, lightweight, and compact tool that can be easily integrated with aerial and marine drones. The device can accurately measure the local magnetic anomalies. It is based on the Atmega 2560 microcontroller and a digital 3-axis fluxgate magnetometer.

Contributo geofisico allo studio dell’intrusione marina nell’area costiera compresa fra Mazara del vallo e Marsala (Sicilia Sud-Occidentale)

Misinterpretation caused by 3D effects on 2D Electrical Resistivity Tomography: tests on simple models

Summary The aim of this work is to evaluate the effects of 2D inversion of electrical resistivity data when in presence on 3D structures by testing synthetic and experimental models. Several numerical simulations have been calculated for different resistivity models and 2D datasets were extracted to study and quantify the effects of 2D inversion on 3D structures. Results have been compared with field texts carried out in quarrying sites. The main tests here presented simulates prism-shaped cavities with a square vertical section of 1 × 1 size and a variable lateral extension d, from 1 to infinity (this latter being a 2D tunnel model). Inversion of predicted data show that 2D tomography does…

SPR survey for archaeological researches: the site of Himera

3D GPR Model in the Military District of San Giacomo Degli Spagnoli (Palermo)

The georadar method was used to try to find some anthropic structures in a large square inside the Carabinieri barracks in the former military complex of San Giacomo degli Spagnoli in Palermo (Italy). These investigations are part of a broader context of a study of the entire area. The purpose of the investigations is to try to understand if under the ground there are the remains of an ancient horse passage that connected the Royal Palace of Palermo with the sea gate of the city. Furthermore, in the Middle Ages, on the site of the present square, there were most likely two churches, which no longer exist, as evidenced by numerous historical testimonies. One of the two, San Giacomo la Mazara…

Georadar Investigations in the Church of San Paolo (San Giacomo Dei Militari, Palermo).

Summary As part of a research project aimed at drawing up a restoration project for the church of San Paolo, the monument was investigated with georadar surveys. The investigations were followed in a targeted manner by archaeological excavations, under the supervision of the Superintendence of Cultural and Environmental Heritage of Palermo. The San Paolo church is located in the oldest part of the city. The geophysical investigations will be useful to identify any pre-existing structures on which the church could be founded. The georadar investigations focused on the central nave and one of the side aisles to identify buried structures and crypts. The data showed several anomalies. One of t…

Indagini microgeofisiche su due dipinti murali di Pietro Novelli

Microgeophysics for the identity of lapideous cultural goods

L’indagine sonica ed ultrasonica come prassi necessaria alla conoscenza di strutture complesse. Il rimontaggio di una statua di epoca romana da Locri: un caso esemplare

Integration of constrained electrical and seismic tomographies to study the landslide affecting the cathedral of Agrigento

The Cathedral of Saint Gerland, located on the top of the hill of Agrigento, is an important historical church, which dates back to the Arab–Norman period (XI century). Unfortunately throughout its history the Cathedral and the adjacent famous Archaeological Park of the 'Valley of the Temples' have been affected by landslides. In this area the interleaving of calcarenites, silt, sand and clay is complicated by the presence of dislocated rock blocks and cavities and by a system of fractures partly filled with clay or water. Integrated geophysical surveys were carried out on the north side of the hill, on which the Cathedral of Agrigento is founded, to define lithological structures involved …

Geological modeling of Altavilla Milicia (Sicily) using HVSR data

At today the use of inversion of HVSR curves is mainly limited to derive average parameters of the shear wave velocity, although recently they have been used also for a detailed reconstruction of the roof of the seismic bedrock (Di Stefano et al. 2014). Since ambient vibrations may contain waves travelling in all directions, as body waves and Rayleigh and Love waves, a limit of this method lies in the uncertain composition of seismic noise, in the lack of knowledge about the microseismic field and in the subjective choices regarding the data processing. This work aims to verify the potential and limits of the HVSR inversion for the purposes of geological reconstruction of the subsoil in hea…

Prove di diagnostica dei legni con metodologie di microgeofisica.

Correlazioni tra le velocità ultrasoniche e le caratteristiche petrografiche in ceramiche archeologiche: un primo approccio metodologico

L’analisi delle velocità degli ultrasuoni permette di investigare i caratteri tessiturali e strutturali e di individuare la presenza di eventuali difetti localizzati all’interno del campione. La loro diffusione negli studi archeometrici è legata alla non distruttività e alla possibilità di fornire risultati accurati in tempo reale. In questo lavoro sono state effettuate numerose analisi petrografiche in sezione sottile e misure di velocità di propagazione degli ultrasuoni su reperti ceramici di interesse archeologico. In particolare sono stati selezionati ed analizzati ceramiche preistoriche ed anfore da trasporto del V-IV sec. a.C., caratterizzati da differente granulometria, composizione …

Contribution of HVSR measures for seismic microzonation studies

The HVSR method applied to seismic noise can be a very useful technique to map the site effects of the territory, to identify the thickness of the soft covering and so the depth of the seismic bedrock. The case of the urban area of Oliveri is presented. Because of its high seismic hazard this area has been subject of first level seismic microzonation. The town lies on a large coastal plain made of mixed fluvial/marine sediments, overlapping a deformed substrate. In order to identify points on the area probably suffering of relevant site effects and to define a preliminary Vs subsurface model, 23 HVSR measurements were performed. A clustering technique of continuous signals has been used to …

Evaluation of Artifacts and Misinterpretation in 2D Electrical Resistivity Tomography Caused by Three-Dimensional Resistive Structures of Regular or Irregular Shapes

Electrical resistivity tomography (ERT) is a well-known geophysical method applied to geological, hydrogeological and geoenvironmental research. To date, 2D ERT is still used much more than 3D ERT, thanks to its greater immediacy, survey speed and lower complexity in processing and inversion. However, the assumption of two-dimensionality of the underground structures can mean that the effects of 3D structures on the 2D ERT can sometimes lead to gross errors in interpretation. This work aims to evaluate these effects by testing synthetic and experimental models. Numerical simulations are performed starting from different resistivity models, and from the results, 2D data sets are derived to s…

Indagini geofisiche integrate eseguite a Palazzo Branciforte

Indagini geofisiche integrate eseguite al Castello di Zena (PC) per lo studio delle fondazioni

Multivariate geophysical survey to detect a shallow fault zone in a landfill project area

An integrated analysis of 2D high-resolution shallow seismic refraction tomographies (SRT) and electrical resistivity tomographies (ERT) has been carried out along a slope where the presence of a fault zone was assumed. It was also applied a post-inversion k-means cluster analysis of the P-wave velocity, the density of the seismic rays and the electrical resistivity of the interpretation models. Distribution maps of the cluster in multi-space were built, allowing to better definethe lateral geometry of a NE-SW directed band composed of intensely tectonized carbonate breccias. Finally, the fracturing and kinematic analysis on fault planes observed along the trenches, highlighted systems of l…

Assessment of a geological model by surface wave analyses

A set of horizontal to vertical spectral ratio (HVSR) and multichannel analysis of surface waves (MASW) measurements, carried out in the Altavilla Milicia (Sicily) area, is analyzed to test a geological model of the area. Statistical techniques have been used in different stages of the data analysis, to optimize the reliability of the information extracted from geophysical measurements. In particular, cluster analysis algorithms have been implemented to select the time windows of the microseismic signal to be used for calculating the spectral ratio H/V and to identify sets of spectral ratio peaks likely caused by the same underground structures. Using results of reflection seismic lines, ty…

“Dice la mamma Rocca”... Metodologie non invasive per il controllo dei manufatti artistici.

Integration of HVSR measures and stratigraphic constraints for seismic microzonation studies: the case of Oliveri (ME)

Abstract. Because of its high seismic hazard the urban area of Oliveri has been subject of first level seismic microzonation. The town develops on a large coastal plain made of mixed fluvial/marine sediments, overlapping a complexly deformed substrate. In order to identify points on the area probably suffering relevant site effects and define a preliminary Vs subsurface model for the first level of microzonation, we performed 23 HVSR measurements. A clustering technique of continuous signals has been used to optimize the calculation of the HVSR curves. 42 reliable peaks of the H/V spectra in the frequency range 0.6–10 Hz have been identified. A second clustering technique has been applied t…

Diagnostic Multidisciplinary Investigations for Cultural Heritage at Etna Volcano: A Case Study from the 1669 Eruption in the Mother Church at the Old Settlement of Misterbianco

Misterbianco is located on the southern flank of Mt. Etna (Unesco site), in eastern Sicily (Italy). This site, also known as Monasterium Album, has a long and tormented history linked with volcanic activity of Mt. Etna and regional seismicity. This site received much attention in the 2000s when excavation works brought to light a 14th century church remains below the thick layer of the 1669 lava. This study documents the first diagnostic multidisciplinary survey performed at this site 350 years after the eruption: the investigations were performed by using techniques such as ground-penetrating radar, infrared thermography, a terrestrial laser scanner and a drone survey to analyze the site’s…

Seismostratigraphic modeling using constrained HVSR Data

An application of HVSR inversion is presented in order to verify the effectiveness of this technique for purposes of reconstruction of the buried geological setting where stratigraphic constraints are available. Specifically, the reconstruction of the stratigraphy in the studied area has been obtained by a seismic-stratigraphic three-dimensional modeling. This allowed for geophysical and geognostic data derived from surveys carried out during this study, as well as previously by the municipality of Palermo.

Physical identification of precious artefacts: their sonic imprint

Comparison of different acquisition patterns for 2D tomographic resistivity surveys

A systematic comparison is presented between some 2D resistivity models and their images by the inversion of synthetic datasets relating to three different arrays, suitable for multichannel data acquisitions (dipole-dipole (DD), Wenner-Schlumberger (WS) and multiple gradient (MG)). The goal is to study how the measurement errors affects the resolution of the tomographic models and the ability to retrieve correct information on buried targets. We considered different data acquisition patterns, gradually increasing the complexity of the combinations of potential spacing and dipolar distance. To this end we increased the number of current dipoles to obtain approximately the same amount of meas…

A Lightweight Prototype of a Magnetometric System for Unmanned Aerial Vehicles

Detection of the Earth’s magnetic field anomalies is the basis of many types of studies in the field of earth sciences and archaeology. These surveys require different ways to carry out the measures but they have in common that they can be very tiring or expensive. There are now several lightweight commercially available magnetic sensors that allow light-UAVs to be equipped to perform airborne measurements for a wide range of scenarios. In this work, the realization and functioning of an airborne magnetometer prototype were presented and discussed. Tests and measures for the validation of the experimental setup for some applications were reported. The flight sessions, appropriately programm…

Integrated geochemical and geophysical surveys for a study of sea-water intrusion

Recenti interventi geofisici e microgeofisici per lo studio dei BB.CC.

Geophysical and geotechnical investigations to support the restoration project of the Roman ‘Villa del Casale’, Piazza Armerina, Sicily, Italy

A multidisciplinary geophysical and geotechnical study, including some non-invasive geophysical applications, was carried out during the restoration of the ‘Villa del Casale’, a Roman villa discovered near Piazza Armerina (Sicily, Italy) in 1929, famous for its Roman floor mosaics. The project aims were to characterize the geology of the subsoil and provide information for solving the main building structural problems including the subsidence of some parts of the floor and the detachment of the tesserae (i.e., the tiles) of the mosaics. Another goal was the detailed study of the underground structures of the Corridor of the Great Hunt, a part of the villa strongly affected by subsidence and…

Integrated Geophysical Investigations at the Greek Kamarina Site (Southern Sicily, Italy)

Kamarina, located in southern Sicily (Italy), was an important Greek colony since its foundation in the sixth century BC. Archaeological excavations, carried out since the twentieth century, uncovered only limited portions of the site so far. Despite the importance of the Greek colony, the presence of remarkable buildings that archaeologists expected to bring to light has not found fully correspondence in the archaeological excavations. Consequently, the integrated geophysical prospection carried out in the study area is aimed to support and address the future archaeological investigations. After the photographic and thermographic survey obtained by an unmanned aerial vehicle, we performed …

Ultrasonic tomographic analysis for getting information on the mechanical structure of ceramic tiles

Surface and volume non-invasive methods for the structural monitoring of the bass-relief ‘Madonna con Bambino’ (Gorizia, Northern Italy)

Structural analysis of marble statues, carried out by non-invasive and in situ methods, is crucial to define the state of conservation of the artworks and to identify the deterioration phenomena that can affect them. In this work, we combined in situ non-destructive techniques, ultrasonic tomography (US), ultraviolet-induced visible fluorescence (UV-IF) and X-ray fluorescence (XRF) to study the bass-relief ‘Madonna con Bambino’ (Gorizia, Italy). The US revealed the presence of some metallic pivots, associated with areas of high sound velocity; moreover, a more degraded area has been identified in the lower part of the bass-relief. The acquired UV-IF image confirmed the presence of surface d…

INDAGINI NON INVASIVE SU ALCUNE COLONNE DELLA VILLA ROMANA DEL CASALE, A PIAZZA ARMERINA

Alcune indagini non invasive sono state eseguite a supporto delle prove di verifica delle colonne prospicienti il Corridoio della Grande Caccia della Villa Romana del Casale, a Piazza Armerina. Scopo del progetto di indagine è la localizzazione di eventuali perni metallici e anomalie interne nelle dieci colonne che separano il Corridoio della Grande Caccia dal Peristilio e valutare il livello di portanza delle singole colonne. A tale scopo sono state eseguite indagini georadar e soniche. Le indagini georadar sono state effettuate utilizzando un apparecchiatura munita di antenna con frequenza centrale di 1000 MHz in modalità monostatica, per ogni colonna, sono stati acquisiti 4 profili verti…

Cluster analysis of HVSR peak datasets to detect geological structures

A modified centroid-based algorithm has been applied to HVSR (Horizontal to Vertical Spectral Ratio) datasets (Nakamura, 2000) acquired for studies of seismic microzoning in various urban centers of Sicilian towns also aimed to obtain detailed reconstruction of the roof of the seismic bedrock (Di Stefano et al. 2014). HVSR data were previously properly processed to extract frequency and amplitude of peaks by a code based on clustering of HVSR curves determined in sliding time windows. In centroid-based clustering, clusters are represented by a central vector, which may not necessarily be a member of the data set. After fixing the number of clusters, the algorithm find the cluster centers an…

Improvement of HVSR technique by cluster analysis

Indagini fisiche a supporto dell’intervento di restauro di una lastra marmorea del II-III d.C.

Seismo-stratigraphic model of “La Bandita” area in the Palermo Plain (Sicily, Italy) through HVSR inversion constrained by stratigraphic data

Ambient noise Horizontal-to-Vertical Spectral Ratio (HVSR) technique is commonly used approach to obtain 1D models of the shear-wave velocity in the shallow surface of an investigated area. However, obtained models can have a wide margin of uncertainty if inversions have not been appropriately constrained by detailed stratigraphic information. An application of HVSR inversion constrained by lithostratigraphic data is presented in order to verify the effectiveness of this technique for purposes of geological and geophysical reconstruction of a sedimentary basin in a densely urbanized area. This is often the case of seismic microzonation studies, in which almost all the information derives fr…

Metodologie di microgeofisica per lo studio ed il monitoraggio di manufatti artistici ed ingegneristici

Dopo una breve introduzione sul significato e sulla crescita storica della Microgeofisica, il lavoro è focalizzato su alcune tecniche tomografiche, sviluppate ed implementate dal nostro gruppo di ricerca, che vengono utilizzate prevalentemente (ma non solo) per lo studio ed il monitoraggio dei manufatti di ingegneria edile e per i Beni Culturali costituiti da materiali lapidei, metallici, legnosi, ecc. In particolare, vengono presentate le seguenti tecniche, tutte caratterizzate dalla non invasività, dalla possibilità di applicazione in situ con strumentazione portatile, da una generale speditività applicativa rispetto a tecniche precedenti. 1. La tomografia sonica, ultrasonica (US) ed elet…

Resolution in wave-field tomographic approach

The Contribution of Electrical Resistivity Measurements to the Analysis of Landslide Events

In order to gain insight into the study of natural avalanches dynamics, we illustrate a statistical model based on a dissipative dynamical variable associated to a position dependent factor of safety field. This model, as experimentally demonstrated, is able to reproduce the complex structure of landslide events, such as power-law distributions. In this paper, we introduce an explicit dependence of the safety factor on the electrical resistivity to simulate landslide events in pyroclastic soils. An application of the model to data acquired in a test area characterized by flowslide events (Monte Albino, Campania Region - South Italy) bear witness the relevant role played by the resistivity m…

Comparison of different sets of array configurations for multichannel 2D ERT acquisition

Abstract Traditional electrode arrays such Wenner-Schlumberger or dipole-dipole are still widely used thanks to their well-known properties but the array configurations are generally not optimized for multi-channel resistivity measures. Synthetic datasets relating to four different arrays, dipole-dipole (DD), pole-dipole (PD), Wenner-Schlumberger (WS) and a modified version of multiple gradient (MG), have been made for a systematic comparison between 2D resistivity models and their inverted images. Different sets of array configurations generated from simple combinations of geometric parameters (potential dipole lengths and dipole separation factors) were tested with synthetic and field dat…

Indagini microgeofisiche integrate sulla statua di Venere Anadiomene (II Sec. A.C.)

Misure microgeofisiche sulla statua del S. Michele Arcangelo (scuola Gaginiana, XVI sec.)

Caratterizzazione e monitoraggio di acquiferi costieri: Studio di un sito ad elevata vulnerabilità all'intrusione marina

Geophysical contribution to the reconstruction of the hydrological model of "Barcellona-Milazzo plain" groundwater body, northen Sicily

The “Barcellona-Milazzo plain” groundwater body in the northen Sicily, was analysed in detail, through numerous geophysical measurements that were integrated with stratigraphic data in order to reconstruct the hydrological model. The “Barcellona-Milazzo plain” (BMP) groundwater body has been identified within the coastal sector between the village of Oliveri, to the west, and Capo Rasocolmo, to the east. It also includes several rivers that rise further south in correspondence with the Peloritani ridge and flow into the wide Barcellona-Milazzo alluvial plain. On the basis of several geophysical and geological data analysis and interpretation have been used to reconstruct the composition and…

A Low Cost Customizable Micro-ROV for Environmental Research - Applications, Advances and Challenges

Summary Several shallow submarines areas are characterized by considerable releases of hydrocarbon gases, which, during earthquakes or volcanic activity, may suddenly and violently occur. In some instances, changes in chemical and physical properties of gas emissions, which are generated by geothermal systems connected to the volcanoes’ plumbing system, are important precursors of volcanic activity and useful indices for the study of the geothermal field. Furthermore, some superficial structures such faults, landslide slopes or archaeological relics should be studied with such a high detail that geophysical and bathymetric surveys are unable to provide. In response to the needs increasingly…

Primi risultati delle indagini geofisiche nei siti archeologici di Mozia (Sicilia Occidentale) e Pollentia (Isola di Maiorca). Progetto FIRB 2003 – Ricostruzione e valorizzazione del paesaggio archeologico in ambiente costiero mediterraneo tramite tecnologie innovative non invasive

Indagini geofisiche in siti archeologici con mosaici: interventi sulla Villa del Casale, a Piazza Armerina

Indagini 3D di dettaglio per l’analisi dell’integrità del busto di Eleonora d’Aragona (F. Laurana, 1468

Imaging Cultural Heritage at Different Scales: Part I, the Micro-Scale (Manufacts)

Applications of non-invasive sensing techniques to investigate the internal structure and surface of precious and delicate objects represent a very important and consolidated research field in the scientific domain of cultural heritage knowledge and conservation. The present article is the first of three reviews focused on contact and non-contact imaging techniques applied to surveying cultural heritage at micro- (i.e., manufacts), meso- (sites) and macro-scales (landscapes). The capability to infer variations in geometrical and physical properties across the inspected surfaces or volumes is the unifying factor of these techniques, allowing scientists to discover new historical sites or to …

Joint interpretation of constrained electrical and seismic models to study the landslide affecting the Agrigento Cathedral

On the stationarity of the horizontal to vertical noise spectral ratio

The Horizontal to Vertical Noise Spectral Ratio (HVNSR) method is nowadays widely used to estimate the resonance frequencies of geological structures. In the HVNSR method, seismic noise is considered as a stationary stochastic process. However, especially in industrialized/urbanized area, this is a very strict assumption seldom occurred. Several sources of noise can generate non stationary and anisotropic microtremor fields. To investigate the stationarity of microtremor, we have carried out several long-term measures of seismic noise with broad-band seismic sensors, in areas where the main source of anthropogenic noise is well known. The signals acquired have been analyzed both in frequenc…

Identification of Precious Artefacts: The Sonic Imprint for Small Artefacts

Identification of artworks is mainly based on a few characteristics which can be observed using non-invasive tools (sight, touch, simple instruments), the investigated properties being geometry, weight, colours, texture, etc. Nowadays, technology allows reproducing all these characteristics to such an extent that even expert conservators can be deceived: in particular at the present time even the geometry of an artwork can be easily reproduced with the help of laser scanner analysis and with a rapid prototyping machine or a computer numerical control (CNC) milling machine. We propose a new tool, the Sonic Imprint, producing a code capable of identifying a rigid artefact from its vibrational…

2d GPR and geoelectrical modelling: tests on man–made tunnels and cavities

B036 2D GPR AND GEOELECTRICAL MODELLING: TESTS ON MAN–MADE TUNNELS AND CAVITIES Introduction 1 Many engineering and environmental projects require geophysical exploration to minimize the geological risk connected with the presence of natural or artificial tunnels and cavities (air and/or water filled). Many studies have been carried out to optimize the procedures to investigate these cavities using many geophysical methods (Beres et al. 2001; Li et al. 2004). In this paper we like to confirm the reliability of combined geophysical methodologies (GPR and ERT) and relative modelling to detect and locate cavities in a particular site (Marsala Western Sicily) where

Metodi geofisici per la ricerca di cavità: caso di studio alle Cave di Marsala (TP)

Many engineering and environmental projects require geophysical exploration to minimize the geological risk connected with the presence of natural or artificial tunnels and cavities (air and/or water filled). In this paper we like to confirm the reliability of combined geophysical methodologies (GPR and ERT) and relative modelling to detect and locate cavities in a particular site (Marsala Western Sicily) where underground dug structures exist. These structures may be used as real artificial physical models, very useful for testing geophysical methodologies. These shallow sandstone caves have, in general, a rectangular shape and are interconnected by tunnels. Most of these structures can be…

Electrical resistivity and induced polarization tomographies to test the efficiency and safety of the new landfill of Bellolampo (Palermo, Italy)

A geophysical study by means of electrical resistivity and induced polarization tomographies was carried out in the landfill site of Bellolampo (Palermo, Italy) to check the integrity of the landfill liner and to detect possible leachate plumes. Preliminarily, synthetic tests were performed, simulating acquisition data along profiles placed above resistivity distribution, suitable to represent landfills protected with an high-density polyethylene (HDPE) liner at the bottom or with possible leachate plumes. Optimized array data sets for parallel measurements have been tested in order to assess the resolution and the effectiveness of tomographic images, comparing inversions with and without t…

New seismological and geological-structural contributions to the support of a seismotectonic model of the hinge area between northern Sicily and southern Tyrrhenian

Study And Monitoring Of Salt Water Intrusion In The Coastal Area Between Mazara Del Vallo And Marsala (South-Western Sicily)

In this chapter the study of a coastal aquifer located in South-Western Sicily (between the towns of Marsala and Mazara del Vallo) is presented, carried out using geochemical, hydro-geological and geophysical techniques. The aquifer has been over-exploited to the point of being subject to intense and worrisome salt-water intrusion. A preliminary chemical and physical characterization of the waters was carried out; this included measuring their conductivity and their chloride content. This allowed to detect the marine intrusion wedge in the coastal aquifer. A series of electromagnetic soundings, suitably calibrated by well logs, were effected in the whole area and allowed to create a 3D inte…

Contribution of the cluster analysis of HVSR data for near surface geological reconstruction

The use of HVSR technique allows in many cases (Bonnefoy-Claudet et al. 2006) to obtain detailed reconstruction of the roof of the seismic bedrock (Di Stefano et al. 2014) and to identify areas with similar seismic behaviour. Theoretical considerations (Nakamura 1989) and experimental tests showed that amplification of horizontal motions between bottom and top of a sedimentary cover is well related to the ratio between the spectra of the horizontal and vertical components of the ground velocity (Nakamura 2000). This ratio is a measure of ellipticity of Rayleigh wave polarization, overlooking Love and body waves contribution. Assuming that subsoil can be represented as a stack of homogeneous…

From Geophysics to Microgeophysics for Engineering and Cultural Heritage

The methodologies of microgeophysics have been derived from the geophysical ones, for the sake of solving specific diagnostic and/or monitoring problems regarding civil engineering and cultural heritage studies. Generally, the investigations are carried out using different 2D and 3D tomographic approaches as well as different energy sources: sonic and ultrasonic waves, electromagnetic (inductive and impulsive) sources, electric potential fields, and infrared emission. Many efforts have been made to modify instruments and procedures in order to improve the resolution of the surveys as well as to significantly reduce the time of the measurements without any loss of information. This last poin…

Integration of stratigraphic data with HVSR measures for studies of seismic microzonation: the case of Oliveri (ME)

The seismic microzoning is a technique of analysis of a territory which aims to recognize, at a small scale, the local geological and geomorphologic conditions that may significantly affect the characteristics of the seismic motion, generating stress on structures that could produce permanent and critical effects. In other words, this technique has the objective to predict and evaluate possible site effects as a result of an earthquake. The first phase of the seismic microzoning is the detailed partition of the territory in homogeneous areas with respect to the expected behavior of soils during an earthquake. The seismic micro-zoning is a tool for prevention and reduction of seismic risk pa…

Method of detecting a sonic imprint of a three dimensional object and related apparatus

Non invasive method used to detect a "sonic imprint" of three-dimensional objects, particularly suitable for the identification and monitoring of artworks, consisting in acquiring the vibrations caused by a source of elastic waves and using a set of detectors fixed in various predetermined points of the external surface of the object. An apparatus, cheap and simple to utilize, suitable to execute this method, is also described.

METHOD FOR DETECTING A SONIC IMPRINT OF A THREE-DIMENSIONAL OBJECT AND RELATED APPARATUS

Non invasive method used to detect a “sonic imprint” of three-dimensional objects, particularly suitable for the identification and monitoring of artworks, consisting in acquiring the vibrations caused by a source of elastic waves and using a set of detectors fixed in various predetermined points of the external surface of the object. An apparatus, cheap and simple to utilize, suitable to execute this method, is also described.

The Corridor of the great hunting scene, Villa del Casale (Piazza Armerina)

Geophysical investigations at the Himera archaeological site, northern Sicily

In this paper we present a geophysical survey that was carried out as a research activity during field trips to the Himera archaeological site, where relics of a large Greek settlement are still buried, effected by a joint group of archaeologists and geophysicists during an educational project. Two-dimensional (2D) resistivity and ground-penetrating radar (GPR) surveys were performed to locate buried archaeological structures at this archaeological site. The results of the GPR surveys show some anomalies characterized by semi-hyperbolic shapes. In some restricted areas of the town, two grids of parallel GPR profiles were acquired while time- and depth-slices were calculated to identify the …

Can be GPR technique useful for strength characterization of concrete?

The possibility of material characterization through the GPR measurements, taking into account the integration with the ultrasonic technique, has been studied and possible relationships between the permittivity of materials and their bulk density are discussed. We present here two different approaches. The first one describes an attempt to correlate the mechanical strength of concrete (as well the ultrasonic velocity) with the permittivity of the material. A series of samples of concrete, characterized by different material properties, were used for georadar and ultrasonic measures, seeking correlations among experimental data. The second approach illustrates the comparison between GPR and …

La GTT, metodologia non invasiva per caratterizzare lo strato esterno degradato dei manufatti lapidei

In questo lavoro viene descritta una metodologia non invasiva ne, tanto meno, distruttiva per studiare il degrado degli strati superficiali dei manufatti lapidei, correlandolo ai parametri di resistenza meccanica. La metodologia adopera come strumento diagnostico la propagazione delle onde elastiche nel mezzo in esame. In particolare, considerando che l'ordine di grandezza degli spessori ricercati è compreso tra le frazioni di millimetro e pochi centimetri, le frequenze delle onde elastiche utilizzabili sono quelle ultrasoniche, dalle decine di kHz ai MHz (e quindi, con velocità di propagazione dell'ordine di 4000 m/s, con lunghezze d'onda dai centimetri alle frazioni di millimetro). Questa…

Seismic investigation for the characterization of a gravity concrete dam

Monitoring of large-scale infrastructures plays an important role for public safety and prevention. The control of the safety assessment of a dam is largely dependent on knowledge of the mechanical parameters of the actual construction, as well as its geological substratum. The application of geophysical methods can considerably contribute to the examination indicating the less consolidated material and the degradation of mechanical parameters. A seismic tomographic approach has been used in a typical gravity concrete dam without reinforcement to detect mechanical properties of the body of the dam and its geological setting. Three seismic travel time tomographies in the dam body as well as …

A contribution to a seismotectonic model of the hinge zone between northern Sicily and southern Tyrrhenian by some seismological and structural constraints

An integrated research on the hinge zone between northern Sicily and its Tyrrhenian off-shore has been carried out, by means of structural, seismological and statistical analyses. The main structural features of the area are represented by both NWSE to W–E striking right-lateral and N–S to NE-SW striking leftlateral fault systems, responsible of uplifting (restraining) and subsiding (releasing) zones. Within this hinge zone the seismicity is mainly located between 10 and 20 km of depth and clustered according to the orientation of the outcropping fault systems. The brittle strain partitioning related to a right-lateral simple shear zone has been reconstructed in the onshore sector, while in…

Virtual three-dimensional model of the subsoil of the church of St. Maria Maddalena d'Alga in Palermo, using high-resolution GPR surveys

The church of Santa Maria Maddalena d'Alga is located in the historic center of Palermo and belongs to the monumental complex of the military district of San Giacomo, in the ancient western fortified area of the city. Today the area hosts a vast military complex, seat of the Command of the Carabinieri Legion of Sicily. The church is elevated with respect to the current floor. During some maintenance works of the church, for the installation of air conditioners, some georadar surveys were carried out to verify the presence of crypts or tombs under the pavement. The investigations made it possible to reconstruct a 3D georadar model and to identify some anomalies under the pavement. Some of th…

Diagnostica per il consolidamento del mosaico pavimentale dell’ambulacro nella villa romana del casale (Piazza Armerina)

Near surface seismostratigraphic modelling of the Bandita plain in Palermo town (Italy) from integra-ted analysis of HVSR and stratigraphic data

The Horizontal to Vertical Spectral Ratio (HVSR) noise method (Nakamura, 1989) is nowadays widely used to estimate the resonance frequencies of geological structures (Bonnefoy-Claudet, 2006). However, often HVSR is also used to obtain information on the depth of the seismic bedrock and on thickness and seismic velocity of the process overburden deposits, using inversion techniques of the H/V curve (Fäh et al., 2003). This nevertheless produce results with large uncertainty intervals of parameters, and then must be necessarily constrained by detailed stratigraphic information. An application of HVSR inversion is presented in order to verify the effectiveness of this technique for purposes of…

Analysis of HVSR Data Using a Modified Centroid-Based Algorithm for Near-Surface Geological Reconstruction

Recently, the use of microtremor techniques for subsoil investigation has increased significantly. The HVSR (Horizontal to Vertical Spectral Ratio) technique allows, in many cases, to obtain a seismo-stratigraphic reconstruction of the subsoil and to identify areas with similar seismic behavior. However, the stratigraphic interpretation of the HVSR peaks still remains a subjective choice and linked to a priori information. A non-hierarchical centroid-based algorithm was modified to group HVSR peaks of different measurements that can be attributed to the same generating seismic discontinuity. Some tests performed have shown that the proposed algorithm produces valid results even in the absen…

Coseismic Damage at an Archaeological Site in Sicily, Italy: Evidence of Roman Age Earthquake Surface Faulting

Archaeoseismology can provide a useful chronological tool for constraining earthquakes and documenting significant evidence that would otherwise be lost. In this paper, we report a case of surface faulting on ancient man-made structures belonging to the archaeological site of Santa Venera al Pozzo situated along the eastern flank of Mt. Etna volcano in eastern Sicily (southern Italy), which is affected by well-developed tectonic faults. Geological surveys highlight a set of fractures affecting the archaeological ruins, suggesting the occurrence of a capable fault zone across the area. An integrated geophysical survey was carried out in order to identify the main subsurface tectonic disconti…

Physical identification of precious artifacts: the sonic fingerprint.

Integrated interpretation of geophysical surveys aimed at tridimensional modeling of a coastal aquifer subjected to sea-water intrusion

Comparison between GPR measurements and ultrasonic tomography with different inversion algorithms: an application to the base of an ancient Egyptian sculpture

By late 2008 one of the most important pieces of the ‘Museo delle Antichit`a Egizie’ of Turin, the sculpture of the Pharaoh with god Amun, was planned to be one of the masterpieces of a travelling exhibition in Japan. The ‘Fondazione Museo delle Antichit`a Egizie di Torino’, who manages the museum, was concerned with the integrity of the base of the statue which actually presents visible signs of restoration dating back to the early 19th century. It was required to estimate the persistence of the visible fractures, to search for unknown ones and to provide information about the overall mechanical strength of the base. To tackle the first question a GPR reflection survey along three sides of…

Quattro esempi di applicazioni geofisiche per l'archeologia a scala medio-piccola

Importance of geological information for geophysical modelling

GPR multi-component data analysis

In order to test the capabilities of ground-penetrating radar (GPR) detection, models were reproduced in a laboratory using both plastic and metal cylinders as well as sheets to represent anomalies buried in a plastic tank containing sand. These models, which represent pipes and dipping layers in a homogeneous medium (i.e., sand), were used to detect the object’s position and study its polarization properties based on the different dielectric contrasts between the object and the surrounding medium. We paid particular attention to the choice of medium through which the wavefield propagated, to be sure of its isotropy and homogeneity, in order for the velocity to be the same for every path tr…

Misure geofisiche utili al progetto di restauro

Investigation of cavity artificial models using 2D GPR and electrical data

Integrated geophysical survey in the archaeological site of Himera (Northern Sicily)

Joint Investigation with Ground Penetrating Radar and Infrared Thermography as a Diagnostic Support for the Restoration of Two Wall Mosaics in the Church of St. Mary of the Admiral in Palermo, Italy

The church of S. Mary of the Admiral in Palermo, known as “La Martorana” and very famous for its Byzantine mosaics, has been a World Heritage site since 2015. The mosaic system of the church includes several groups of figures and scenes from the life of the Virgin Mary. From the western part of the ancient church only two mosaics survive, detached from their original position, and are now located in two internal chapels. On the occasion of several restoration works, these two mosaic panels were investigated with non-invasive techniques, in order to provide diagnostic support to the restoration and consolidation interventions. The investigations were aimed at detecting any air po…

Recognition of earthquake-induced damage in the Abakainon necropolis (NE Sicily): results from geo-morphological, geophysical and numerical analyses

Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to th…

Selection of time windows in the horizontal-to-vertical noise spectral ratio by means of cluster analysis

The selection of the elementary analysis windows in continuous noise recordings for optimal estimation of the mean horizontal‐to‐vertical spectral ratio (HVSR) curve is generally performed by visual inspection of HVSR curves considered as functions of time. Starting from full‐length records, HVSR curves are determined in consecutive time windows of appropriate lengths. Time windows with HVSR curves that are anomalous on the basis of a simple visual inspection are generally ignored in the computation of the average HVSR curve. It is often very difficult to optimize the selection of time windows to be used for the calculation of the HVSR curve representative of a site. The use of nonobjective…

CAMPAGNA DI INDAGINI NON DISTRUTTIVE SULLA CATTEDRALE DI AGRIGENTO

Geophysics and cultural heritage. A living field of research for Italian geophysicists

If one reads the World Heritage List 2002/2003, (http:// whc.unesco.org/archive/WHList02-ENG.pdf), a datum comes out with evidence: 12 countries have 253 World Heritage Sites (WHS) and all the 125 member countries have 586 WHS. Within these 12 countries Italy has 35 WHS corresponding to about 6% of the whole, followed by Spain, 5.8%, France, 4.6%, and the tenth has less than 2% of WHS. Cultural heritage is one of the greatest riches of Italy. Europe, with China, is the land which has the most stratified history in the world, and Italy is likely to still have undiscovered settlements dating from the prehistoric age to the 18th century. Some areas are totally unexplored, others have been only…

Geophysical prospection of the Roman city of Pollentia, Alcúdia (Mallorca, Balearic Islands, Spain)

Abstract We present the results of the geophysical investigation carried out in the Roman city of Pollentia, in the island of Mallorca. The ancient city was identified in the 19th century. Old and new archaeological excavations have helped to uncover a residential area, a theatre, the forum, several necropolises and other remains of the city, but a large unexplored area has still to be investigated. For instance, the limits of the ancient town and the presence of harbour structures are still unknown. The geophysical survey has covered an area of more than 20.000 m2 by integrating magnetic, electromagnetic, electrical and ground penetrating radar (GPR) methods. Many unseen archaeological fea…

Indagini geofisiche a supporto dell’intervento di restauro di Palazzo Branciforte (Palermo)

Assessment of the Reliability of the SPAC Method in Urban Areas

We have carried out several long-term measures of seismic noise with triangular arrays of broad-band seismic sensors, to investigate the reliability of the SPAC method in urban areas. We investigate the stationary and anisotropy of the microtremor wave field. We have found that the anisotropy of the microtremor wave field can be evaluated analyzing the HVNSR as function the azimuth. Furthermore, we showed as strong anisotropies in the microtremors are often observable in particular at high frequencies (> 1 Hz). We have verified as microtremors can be difficult to considered as ergodic processes, and for this reason time averaging, also even over a long periods of time, cannot replace an app…

Advances in microgeophysics for engineering and cultural heritage

A large number of unconventional investigations have been implemented, tested, and validated in the field of microgeophysics, with the aim being to solve specific diagnostic and/or monitoring problems regarding civil engineering and cultural heritage studies. The investigations were carried out using different tomographic 2D and 3D approaches as well as different energy sources, namely sonic, ultrasonic and electromagnetic (radar) waves, electric potential fields, and infrared thermography. Many efforts have been made to modify instruments and procedures in order to improve the resolution of the surveys as well as to greatly reduce the time of the measurements without any loss of informatio…

Structural investigations by infrared thermography and SPR

Metodo di rilevamento di una impronta sonica di un oggetto tridimensionale e relativo apparato

Electromagnetic and ultrasonic investigations on a Roman marble slab

The archaeological museum of Rome asked our group about the physical consistency of a marble slab (second to third century AD) that recently fell during its travel as part of an exhibition. We decided to use different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate the internal coupling pins, and ground-penetrating radar (GPR) (2000 MHz) and ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the hidden ones. For the ultrasonic data, tests were carried out to optimize the inversion parameters, in particular the cell dimensions. Surely, the choice of cell size …

Cluster analysis for cavity detection using seismic refraction and electrical resistivity tomography

Geophysical methods (in particular ERT technique) constitute an excellent tool for the detection of buried cavities. However the integration approach of e different geophysical methods could minimize the ambiguity of geophysical interpretation of the buried cavity. The technique of electrical tomography has been joined to the technique of seismic refraction tomography in order to obtain more robust interpretations. Many tests have been carried out using synthetic data and experimental ones. It was finally used a statistical approach based on cluster analysis of the P-wave velocity, the density of the seismic rays and the electrical resistivity of the synthetic and experimental models. Distr…

Identification of Precious Artefacts and Stones: The sonic Imprint

Physical identification of precious artefacts: the sonic fingerprint