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…

Sensitivity Analysis Of Multi-Electrode Arrays For Characterizing The Non-Saturated Zone In Groundwater Vulnerability Assessment

The near-surface environment acts as a filter and buffer for contaminants introduced from the surface by anthropogenic activities. For this reason there is a great need to improve our understanding of the shallow subsurface taking into account the increasing demand for vulnerability maps which illustrates the exposure of aquifers against pollution. These maps are designed to show areas of greatest potential for groundwater contamination on the basis of local subsurface conditions. A shallow, unconfined sand-and-gravel aquifer is highly vulnerable to pollutants because rapid recharge gives little time to contaminants to degrade naturally or be adsorbed before reaching the aquifer. Conversely…

Caratterizzazione geofisica dell’acquifero idrotermale dell’area di Panza (Ischia)

Gli obiettivi di questo lavoro sono quelli di ricostruire, con metodologie geofisiche integrate, le principali geometrie tettoniche ed idrogeologiche del territorio di Panza nell'isola di Ischia. La zona è stata scelta in quanto caratterizzata da un'intensa attività idrotermale e deformativa connessa con la presenza di un reservoir geotermico.

Geophysical study of the hydrothermal reservoir in the Panza area (Ischia, Italy)

The aim of the work is the reconstruction of the main geometric pattern and the characterisation with geophysical parameters of geological structures lying at small and medium depths in an area of the Ischia island (Italy), where a sensible hydrothermal activity is present.

Metodo ed apparato di rilevamento tomografico di una distribuzione di resistività in un mezzo

Metodo di rilevamento tomografico di una distribuzione di resistività di un mezzo comprendente tre fasi: predisposizione su una porzione della superficie del mezzo di una griglia di elettrodi collegati con almeno un generatore elettrico; selezione dalla griglia di una pluralità di secondi elettrodi collegati con un misuratore di potenziale elettrico; immissione attraverso la prima coppia di elettrodi di una corrente elettrica suscettibile di generare un campo elettrico nel mezzo; misurazione dei potenziali elettrici in corrispondenza dei secondi elettrodi per ricavare differenze di potenziale tra coppie a scelta di secondi elettrodi; calcolo della distribuzione di resistività mediante le di…

La metodologia MYG per eseguire tomografie elettriche 3D su oggetti che presentano una superficie di pregio artistico

La tomografia elettrica di resistività è poco utilizzata nello studio delle murature di edifici di pregio artistico, malgrado le potenzialità in termini di risoluzione: attraverso indagini tridimensionali è infatti possibile ottenere tomografie di resistività 3D dettagliate e rappresentative. La necessità di inserire "chiodini" per immettere la corrente ne limita però l’applicabilità su superfici di pregio. Abbiamo superato questa limitazione sviluppando una metodologia (MYG) che riduce drasticamente rispetto ai metodi classici il numero degli elettrodi utilizzati per immettere la corrente (circa15 volte) ed il tempo di acquisizione (circa 50 volte), permettendo l'uso di elettrodi non invas…

The MYG methodology to carry out 3D electrical resistivity tomography on media covered by vulnerable surfaces of artistic value

Electrical Resistivity Tomography (ERT) is not yet frequently used in the study of walls, floors and foundations of buildings of artistic value, like Ground Penetrating Radar (GPR) or other commoner techniques, although it exhibits a great potentiality in terms of resolution power. The main limitation for the applicability of ERT to the Cultural Heritage field arises from the method of current injection: it is often necessary to drive current electrodes into small perforations on the acquisition surface in order to get a current flow sufficient to obtain a good signal-to-noise ratio. To overcome this limitation the Maximum-Yield Grid (MYG) methodology has been developed, in which only a small fr…

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 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.

A specific operative protocol set up during the restoration of the Grammichele's slate slab

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…

NEW 3D ELECTRICAL TOMOGRAPHY TECHNIQUE FOR INVESTIGATIONS ON VULNERABLE SURFACES

L’identificazione fisica dei manufatti di pregio: la “firma sonica”

The New "Maximum Yield Grid" (MYG) Array in Full 3D Resistivity Tomography

Over the past few years geoelectrical prospecting has experienced many innovations, ranging from instrumental refinements to improvement of data interpretation. The consequence of this has been a strong increase in the method s resolution power and, therefore, its field of application has broadened. Nevertheless, the diffusion of 3D surveys in electrical resistivity tomography has been very much limited by the long acquisition time required by this kind of investigation, as compared to 2D ERT or other geophysical exploration methods like GPR. However, 3D ERT has a great advantage in terms of resolution power, that is very important in many applications, such as archeological or cultural her…

Use of special GPR techniques to solve engineering and environmental problems

Microgeofisica per lo studio dei beni culturali movimentabili

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

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 no-invasive methodology to detect the external decayed layer of lapideous artefacts.

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

Approaching electrical tomography

A general approach to electrical tomography is here described, based on the distribution of the experimental data to the set of voxels in which the subsoil has been divided. This approach utilizes the sensitivity coefficients as factors of the convolution procedure to execute the back projection of the data, to obtain the 3D pictures of the subsoil. A subsequent probabilistic filtering technique is described to improve the pictures in view of sharp boundary models. Some models are finally presented, mostly regarding cubic buried anomalies as well as pipe-shaped and L-shaped anomalies.

Unconventional micro-geophysics for engineering and cultural heritage artifacts

Some of the unconventional micro-geophysical investigations that have been implemented and/or assessed in the frame of the activity for engineering and cultural heritage studies are here presented. In particular the investigations were carried out using different tomographic 2D and 3D methodologies: ultrasonic and electromagnetic (radar) waves, electric potential field and IR termography. The results suggest that that there will be further improvements in the future, so that the application of these methodologies will be used even more to diagnose, monitor and safeguard both engineering as well as cultural patrimonies.

ALCUNE MODIFICHE MIGLIORATIVE ALLA BACK-PROJECTION RESISTIVITY TECHNIQUE (BPRT)

SPR survey for archaeological researches: the site of Himera

L'impronta sonica di manufatti di interesse artistico e oggetti museali

Viene presentata una nuova tecnica di indagine non invasiva, sicura e rapida, per l’identificazione univoca e per il monitoraggio dell’integrità di manufatti costituiti da materiali rigidi, quali vasellame, statue e in generale oggetti lapidei, metallici o lignei. La tecnica sfrutta la capacità degli oggetti di vibrare se sollecitati da una sorgente esterna artificiale e si basa sullo studio delle oscillazioni smorzate indotte. Così è possibile costruire una impronta sonica degli oggetti stessi, una sorta di DNA che li possa identificare senza alcun dubbio ed eventualmente possa anche valutarne lo stato di consistenza meccanica (o integrità) come monitoraggio nel tempo. L’applicazione della…

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

Use of the linear grid array in 2D resistivity tomography

Tripotential data processing for HES interpretation

In this paper some methods are proposed and compared to correct the experimental measurements for preliminary processing of tripotential data which are acquired for HES prospecting. However, the use of those methods should be based upon an accurate analysis of all experimental data. Such an analysis ought to involve: 1) an estimate of the averaged measurement errors with their variance and distribution in both the space and the three apparent-resistivities domains; 2) the choice of a resistivity model capable of describing the actual volume under study. The differences among the three values of apparent resistivity measured on a point are generally influenced both by the resistivity distrib…

Comparative tests on different multi-electrode arrays using models in near-surface geophysics

In this paper, the response of different synthetic models to geoelectrical multi-electrode surveys is studied. The models considered are related to two main problems, which are very common in geophysical research regarding hydrogeology and engineering. The first class of models represents buried walls, similar archaeological remains or remains of buried foundations; the other class corresponds to a sea-water intrusion of a fresh water aquifer, which is generally studied in hydrogeophysics. A set of 2D simulations, starting from the synthetic models, was carried out to compare the behaviour of the different arrays when acquiring measurements of electrical resistivity tomography. For each mod…

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 …

Indagini geofisiche integrate eseguite a Palazzo Branciforte

Il nuovo stendimento MYG per la tomografia geoelettrica Full 3D

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

Metodo di rilevamento di caratteristiche fisiche di strati costituenti un oggetto tridimensionale

Physical identification of precious artefacts: their sonic imprint

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…

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

Geophysical investigations in the Flumendosa River Delta, Sardinia (Italy) — Seismic reflection imaging

A geophysical investigation that included seismic-reflection surveying and time-domain electromagnetics (EM) was carried out in the Flumendosa River Delta plain in southeastern Sardinia, Italy. The objective was to improve knowledge of geologic and hydrogeologic controls on a highly productive aquifer hosted in thick Quaternary deposits and known to be affected by an extensive saltwater intrusion. The seismic reflection survey, whose results are reported here, aimed to image the Paleozoic bedrock topography and to obtain detailed structural and stratigraphic information on the sequence of largely fluvial sediments extending from the surface down to bedrock. The survey consisted of two inli…

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

Implementation to Back-Projection Techniques of Resistivity Data

In order to obtain well contrasted images by back-projection of resistivity data some modifications to the back-projection algorithm as well as the use of filtering techniques for the sensitivity matrix were proposed (Kotre 1994; Cosentino et al. 1998). To further improve the back-projection algorithm a new implementation is here suggested. Besides a subsequent filtering algorithm of the sensitivity coefficient matrix is proposed. It is aimed to increase resistivity contrasts and to reduce smoothness in tomographic final representation. Finally the proposed technique is tested on synthetic data.

An approach to the electrical tomography aimed to the investigation of particular confined structures

In this paper we present a practical approach to the electrical tomography when applied to materials having particular shapes (like the columns). Simple cylindrical shapes have been tested, and the general model has been selected as a set of elements having circular sections of some angle and thickness.

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

Non-invasive Geophysical Surveys in Search of the Roman Temple of Augustus Under the Cathedral of Tarragona (Catalonia, Spain): A Case Study

An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. 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 renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious…

Geophysical methods

Per cominciare la geofisica e la micro-geofisica con qualche strumento di base

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

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

Comparative tests of some multi-electrodic arrays using models of particular interest in engineering and environmental geophysics

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

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

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

3D ERT for the study of an ancient wall covered by precious mosaics

The DC electrical tomography (ERT) is still a method scarcely diffused for the study of masonry of recent and ancient buildings, in spite of the very high resolution power of this methodology. The major limitation on ERT applicability on precious surfaces (like masonries or floors with fresco or mosaic covering) depends on the method of current injection: usually it is necessary to drive electrodes (small nails) into small perforations on the surfaces, to obtain sufficiently high current values (to produce good signal to noise ratio). An interesting application of the MYG array (that reduces significantly, compared to other classical arrays, the number of electrodes utilized for current inj…

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…

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…

Inverse problem for tripotential measures in the study of buried cavities

This paper presents a solution to the inverse electrical problem for the interpretation of apparent resistivity anomalies due to empty buried cavities of quasi-spherical shape when tripotential measures are carried out. The anomalies of the apparent resistivities ra,rb andrg,and the composed resistivitiesrmand rt were previously calculated for a sufficient class of spherical models of resistivity anomalies. Then, for the whole class of models, some functionals of spatial distribution of the apparent and composed resistivity were identified and analyzed. They represent the average characteristics of the anomalies and, depending in a simple way on the fundamental parameters of the sources of …

Confronto del potere risolvente di differenti configurazioni elettrodiche nella prospezione geoelettrica su modelli 2D

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…

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…

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

Geophysical study of an landslide in northern Sicily

The San Fratello area in the Nebrodi Mountains (northern Sicily) is a region of high instability. It has suffered many devastating occurrences, which have hit and destroyed the village of San Fratello. At present the area is still subject to a high landslide risk. A series of geophysical surveys have been carried out with the aim of determining the thickness and dimensions of the landslide body as well as some tectonic features, in order to gain insight into the evolution of the landslide. The following geophysical techniques have been used: borehole seismic tomography, i.e. down-hole tomographic seismic soundings (DH TSS), time-domain electromagnetic (TDEM) soundings and georadar profiling…

Geoelectrical study of archaeological structures in the Himera plane (North-western Sicily)

This paper presents the results obtained from a geoelectrical study carried out on the Himera plane for archaeological research. Both the tripotential method and the dipole-dipole profile method have been used on a 40 m ´ 40 m investigation area in order to obtain several resistivity maps. The latter show different geoelectrical anomalies, the shape of which allows us to interpret simple archaeological structures, consistent with current knowledge of ancient Himera sites. Furthermore, the study of the whole set of data in the resistivity domain has allowed us to infer some other characteristics from the subsequent geological process of alluvial covering of the site.

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…

Archaeological excavation confirms the geophysical anomalies recorded at the cathedral of tarragona - A comparative study

An integrated geophysical survey was conducted in September 2007 at the Cathedral of Tarragona to search for archaeological remains of the Roman temple dedicated to the Emperor Augustus. Many hypotheses about its location have been put forward, the most recent ones suggesting it could be inside the present cathedral. A project including Electrical resistivity tomography (ERT) and Ground probing radar (GPR) was planned for a year and conducted during a week of intensive field survey. Both ERT and GPR provided detailed information about subsoil structures. Different ERT techniques and arrays were used, ranging from standard Wenner-Schlumberger 2D sections to full 3D electrical imaging using t…

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)

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

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 …

Identification of Precious Artefacts and Stones: The sonic Imprint

Physical identification of precious artefacts: the sonic fingerprint