Time-domain-induced polarization: Full-decay forward modeling and 1D laterally constrained inversion of Cole-Cole parameters

Time-domain-induced polarization has significantly broadenedits field of reference during the last decade, from mineralexploration to environmental geophysics, e.g., for clay and peatidentification and landfill characterization. Though, insufficientmodeling tools have hitherto limited the use of time-domaininducedpolarization for wider purposes. For these reasons, anew forward code and inversion algorithm have been developedusing the full-time decay of the induced polarization response,together with an accurate description of the transmitter waveformand of the receiver transfer function, to reconstruct thedistribution of the Cole-Cole parameters of the earth. The accuratemodeling of the tra…

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.

Sequential and joint hydrogeophysical inversion using a field-scale groundwater model with ERT and TDEM data

Abstract. Increasingly, ground-based and airborne geophysical datasets are used to inform groundwater models. Recent research focuses on establishing coupling relationships between geophysical and groundwater parameters. To fully exploit such information, this paper presents and compares a joint hydrogeophysical inversion (JHI) approach and sequential hydrogeophysical inversion (SHI) approach to inform a field-scale groundwater model with Time Domain Electromagnetic (TDEM) and Electrical Resistivity Tomography (ERT) data. The implemented SHI coupled inverted geophysical models with groundwater parameters, where the strength of the coupling was based on geophysical parameter resolution. To t…

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…

Application of time domain induced polarization to the mapping of lithotypes in a landfill site

A direct current (DC) resistivity and time domain induced polarization (TDIP) survey was undertaken at a decommissioned landfill site situated in Hørløkke, Denmark, for the purpose of mapping the waste deposits and to discriminate important geological units that control the hydrology of the surrounding area. It is known that both waste deposits and clay have clear signatures in TDIP data, making it possible to enhance the resolution of geological structures compared to DC surveys alone. <br><br> Four DC/TDIP profiles were carried out crossing the landfill, and another seven profiles in the surroundings provide a sufficiently dense coverage of the entire area. The whole dataset w…

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…

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…

Improvement in MRS parameter estimation by joint and laterally constrained inversion of MRS and TEM data

We developed a new scheme for joint and laterally constrained inversion (LCI) of magnetic resonance sounding (MRS) data and transient electromagnetic (TEM) data, which greatly improves the estimation of the MRS model parameters. During the last few decades, electrical and electromagnetic methods have been widely used for groundwater investigation, but they suffer from some inherent limitations; for example, equivalent layer sequences. Furthermore, the water content information is only empirically correlated to resistivity of the formation. MRS is a noninvasive geophysical technique that directly quantifies the water content distribution from surface measurements. The resistivity informatio…

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…

Microgeofisica per lo studio dei beni culturali movimentabili

Mapping of landfills using time-domain spectral induced polarization data: the Eskelund case study

This study uses time-domain induced polarization data for the delineation and characterization of the former landfill site at Eskelund, Denmark. With optimized acquisition parameters combined with a new inversion algorithm, we use the full content of the decay curve and retrieve spectral information from time-domain IP data. Thirteen IP/DC profiles were collected in the area, supplemented by el-log drilling for accurate correlation between the geophysics and the lithology. The data were inverted using a laterally constrained 1D inversion considering the full decay curves to retrieve the four Cole-Cole parameters. For all profiles, the results reveal a highly chargeable unit that shows a ver…

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)

Apparato modulare per la prospezione elettrica di un mezzo

SPR survey for archaeological researches: the site of Himera

Transmitter waveform and receiver transfer function modelling in time domain induced polarization

SUMMARY In the computation of the forward response for Time Domain Induced Polarization the incomplete description of the transmitter waveform causes dramatic errors in the estimation of the magnitude and time characteristic of the IP phenomenon. Both the duration of the current pulse and the sequence of pulses used for the stacking procedure have a strong effect in the magnitude and shape of the IP decays. Furthermore, it is important to model low-pass filters of the receiver system, in order to extract all the information contained in the acquired data. For these reasons, a new 1D forward and inversion algorithms have been developed using the full time decay of the IP response and the rec…

Ferricytochrome c encapsulated in silica nanoparticles: structural stability and functional properties.

Using a modified sol-gel technique, we have succeeded in encapsulating ferric cytochrome c in silica nanoparticles obtained from hydrolysis and polycondensation of tetramethylorthosilicate. Particles dimensions have been determined with dynamic light scattering; this technique yields an hydrodynamic radius of about 100 nm, each nanoparticle containing about 10(2)-10(3) proteins. If stored in the cold at low ionic strength, nanoparticles are stable for more than one week, even if a slow radius increase with time is observed. CD measurements show that encapsulated proteins exhibit substantially increased stability against guanidinium hydrochloride induced denaturation. Reduction kinetics of e…

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

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.

Il nuovo stendimento MYG per la tomografia geoelettrica Full 3D

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

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.

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

Data repeatability and acquisition techniques for Time-Domain Spectral Induced Polarization

The Time Domain Induced Polarization (TDIP) technique is widely used in applied geophysics, particularly for environmental issues, for instance for delineating landfills or detecting leachate percolation. Because the reliability of IP data remains an issue at the field scale, this paper deals with the factors controlling data quality and compares different arrays and acquisition parameters for optimal collection of data in the field. The first part focuses on repeatability experiments carried out in the former Horlokke landfill (Denmark), in order to infer the degree of which a signal can be reproduced over time. Results show a good repeatability, with on average less than 10% of difference…

Efficient full decay inversion of MRS data with a stretched-exponential approximation of the distribution

SUMMARY We present a new, efficient and accurate forward modelling and inversion scheme for magnetic resonance sounding (MRS) data. MRS, also called surface-nuclear magnetic resonance (surface-NMR), is the only non-invasive geophysical technique that directly detects free water in the subsurface. Based on the physical principle of NMR, protons of the water molecules in the subsurface are excited at a specific frequency, and the superposition of signals from all protons within the excited earth volume is measured to estimate the subsurface water content and other hydrological parameters. In this paper, a new inversion scheme is presented in which the entire data set is used, and multi-expone…

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…

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

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…

Water and proteins confined in silica hydrogels and silica nanoparticles: structural, dynamic and functional studies.

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…

Valutazione di differenti quadripoli e sequenze di misura per tomografie elettriche in contesti industriali e costieri

Modular apparatus for the electric prospection of a medium

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

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 …

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)

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

Importance of geological information for geophysical modelling

Misure geofisiche utili al progetto di restauro

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

Identification of Precious Artefacts and Stones: The sonic Imprint

Physical identification of precious artefacts: the sonic fingerprint