Regione Siciliana Assessorato Beni Culturali ed Ambientali e della … · 2016. 1. 25. ·...
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Regione SicilianaAssessorato Beni Culturali ed Ambientali e della Pubblièa IstruzioneDipartimento Beni Culturali ed Amblentali ed Educazion4e Permane~teCentro Regionale per la Progettazione e il Restauro
Centro Regionale per la Progettazione ed il Restauroe per le Scienze Naturali ed Applicate ai Beni Culturali
Scienza e Patrimonio Culturale nel Mediterraneo
DIAGNOSTICA E CONSERVAZIONE
ESPERIENZE E PROPOSTE PER UNA CARTA DEL RISCHIO
Atti del m convegno internazionale di studiLa materia e i segni della storia
Palermo 18-21 ottobre 2007
REGIONE SICILIANA
Assessorato dei Beni Culturali ed Ambientali e della Pubblica Istruzione
Dipartimento Beni Culturali ed Ambientali ed Educazione Permanente
Palermo
INDAGINI E DIAGNOSTICA - terza parte
256 Radiologia versus diagnostica per immagini nell'arteG. Salerno
266 La riflenografia infrarossa ad alta risoluzione: un unico processo dalla ripresa alla stampa dei riflettogrammi.C. Perez Garda, P. lneba T'amari/,]. Perez Miralles, L. Pini, G. Valagussa
269 Physical identification of precious artefacts: their sonic imprintP. L. Cosentino, P. Capizzi, G. Fiandaca, R. Martorana, P. Messina, I. Razo Amoroz
277 Integratecl archaeological and geophysical survey for searching the Roman of Augustus tempIe in Tarragona,Spain
A. Casas, P.L. Cosentino, Y Diaz, E. Garcia, M. Himi, M. Lafuente, R. Mar/orana, J.M. Macias, J. Menchòn, A.Murnoz, R. Sala, 1, Teixell
284 Indagini archeopalinologiche in Sicily at Taormina, Piazza Armerina and MoziaF Terranova, C. A. Accorsi, M. Bandini Mazzanti, A. M. Mercuri, P. T0171,E. Manicardi, /VI. C. Montecchi, L.Olmi, R. Rinaldi, A. Valenti, F Benassi, P. pensabene, S. Tusa
295 Materia e segni della storia sostanzialmente e formalmente uniti: alcuni casi di studioS. Lorusso, C. Malteucci, A. Na/ali, S. Tumidei
304 Caratterizzazione spettrale e visiva dei materiali antichi per l'ottimizzazione della progettazione iIIuminotecnicaF Gugliermelti, F Bisegna, L. Monti
INDAGINI E DIAGNOSTICA - quarta parte
314 PRErAZIONI di Claudia Sorlini
316 On the efficiency of biocides and cleaning treatments in restoration works of subterranean monumentsE. Aka/ova, M. Roldan, M. Hernandez-Marine, ].M. Gonzalez, C. Saiz-}imenez.
323 A non-invasive approach to the polyphasic study of biodeteriogenic biofilms at St Agatha crypt and catacombsat Rabat, Malta.G. Zammit, F De Leo, C. Urz~ P. Albe1tano
328 Studio della colonizzazione microbica di tessere mosaicali mediante tecniche fisiche e molecolariF. Palla, S. Drago, M. R. Di Pierro, A. Lanza, G. Morici
333 Express-method of estimation of biocide properties of different materials and substances and application ofnanotechnology in biocide treatmentM. Dmitrieva, N. Reb11kova
337 Colonization by actinobacteria in the cave of Dona Trinidad (Malaga, Spain)F Stomeo,J.M. Gonzalez, C. Saiz-jimenez
INTEGRATED ARCHAEOLOGICAL AND GEOPHYSICAL SURVEY FOR SEARCHING THEROMAN TEMPLE OF AUGUSTUS IN TERRAGONA, SPAINA.Casas, PL.Cosenlino, Y Dfaz, G. Fiandaca, E. Garcfa, M. J-limi, M.
ù(jilenle, R. Mm1orcma,j.M lvlacfas,j. Menehon, A. i\;/1I/10Z, R. Sala,
l. 'f'eLx°ell
INTRODUCTION
Tarragona's cathedral is located on the highest topo
graphic pIace of the city. Romans occupied this space
since the III century B.e. and converted it on a military
camp since the wars against the Carthaginian, com
manded by Hannibal, took pIace in the Iberian
Peninsula. Subsequently, Tarraco was the pIace where
the Roman soldiers arrived to conquer Hispania.
Fig. 2 - Front of the Gothic Cathedral of Tarragona.
INDAGINI E DIAGNOSTICA •
Fig. 1 - !dealized illustration of
the Au-gustus tempie in a coinof Tiberian's emperor age.
The evidence of this activity is the Roman wall that has
been preserved and stili surrounding the historic center
of Tarragona CAqllilllé, 2000),
After getting the rank of provincial capital, Tarraco start
ed a set of urban transformations presided over the hill
by a great sacred enclosllre that surrollnded the tempIe
devoted to the emperor Augllst. It is worth noticing that
Fig. 3 - Plant of the Gothic Cathedral overdrawn are assllmed the external structllre of sacred area (dots).
Il S C I E N Z A E P A T R I M O N I O C U L T U I{ A L E [) E L M E [) I T E R R A N E O
the Roman cult was carried out outsicle of the templesancl not insicle.
Since the encl of the IV centll1Y A.C. (the Christian religion
was then the official one of the Roman Empire), the
emperors ordered a graduai legislative process that
favored the replacement of the pagan cults with the
Christian ones. At this time, the site undelwent manychanges in urban planning and ideological reassessments.
During the V ancl VI centuries, the urban characteristics
of this zone changecl radically with residential spaces
inciuding open-air waste clumps-ancl spaces for offidalrepresentations both civil and religious.In this framework also the Meclieval Catheclral was erect
ecl with the Bishopy ancl burial grouncl spaces.
At the beginning of the VIII centll1Y the Islamic invasion hada period of decline far more than four centuries unti! the
clefinitive restoration of the metropolitan bishop and the
starting of the new meclieval cathedral in the micldle of the
XII centll1y. Since this time, the Catheclral has dominated the
skyline of Tarragona and probably concealing in the subsoil
some of the answers we need to recognize ancl unclerstancl
the historical evolution of the city (Munoz, 2001).The usefulness of geophysical techniques (e.g., dc current, electromagnetic, ancl magnetic methocls) for archae
ological investigation is well known :mcl has been repolt
ecl in many papers, for instance Casas et al. (1995), Dabas
et al. (1993), Pérez-Garcfa (2000), Carrara et al. (2001),
Negri ancl Leucci (2006). Therefore, as the latest archaeo
logical researches from Macfas et al. (2007) assumed that
there are remains of older builclings uncler the Meclieval
See, related to the Roman emperor, a geophysical survey
was consiclerecl - also taking into account the potential
interest of the remains. The objective was to obtain a first
picture of the archaeological remains existing in the subsoil without disturbing both the religious cult ancl the cul
turaI visits to the tempie.
On the other hancl, the obtained results will be consicl
erecl of interest to clefine some strategies in the futurefourth phase of Director Pian for the Cathedral of
Tarragona (Figuerola et aL, 2002). The aim of the geo
physical survey is to get as much information as possible
on the structure and composition of the materials existing
in the subsoil and, particularly to cletect remains of foun
dations of previous builclings. For this reason, a cletailecl
geophysical mapping has been concluctecl.
METHODOLOGIES
The geophysical methocls used in this stucly area arebased on the cletection of variations in the electric ancl
electromagnetic propelties of the subsoil and the use of
these data for identifying altifacts ancl clistinguishing themfrom the natural variations of the subsoil. EI{T,FDEM ancl
GPR were appliecl.
Geophysical investigations play an important role in
defining shallow subsurface structures. In particular,their application is a non-clestructive and cost effective
way to locate buried archaeological structures in the sur
veyecl areas. Taking into account prececling experiences
in other similar surveys three complementary geophysical methods were plannecl:
-Electrical resistivity tomography (EI{T)-Frequency domain electromagnetics (FDEM)
-Grouncl probing raclar (G PR)
The first method (ERT) aimecl to recognize the geometrical characteristics of the structures of the subsoil as a
function of the electrical resistivity of the materials that
constituted the subsoi!, which in tum depends on theporosity, ciay content ancl water content.
This methocl was carried out using two clifferent multi
channel resistivity meters. An Iris Syscal Plus with 48
channels for recording 2]) sections ancl a MRS256 Systemfrom G F Instruments with 350 channels for 3D moclels. In
both cases, the proceclure for clata acquisition was to
apply a DC electrical current by means of two electroclesand to measure the potential generatecl over two other
electrocles placed along profiles (2D-ERT) or regular gricls
(3D-ERT) spacecl one meter apan over the pavement. In
order to cany out the bi-dimensional profiles, stainlesssteel flat-base electrocles were used, similar to those usecl
by Athanasiou et al. (2004), while to clecrease the contact
resistances a concluctive gel was placed between the
metallic electrocles ancl the soil pavement; with this strategy the contact resistances were set below 10 kohms.
--....-.-/
Fig. 4 - Pictllre showing a portion of a 2D alTay lIsing the f1at-base stainless-stecl clectrodes.
Fig. 5 - Pictllre showing aspect of a 3D array covering a signifycant arca of the cathedral.
INDAGINI E DIAGNOSTICA Il
Fig. 6 - Distriblltion of the ali the electrodes lIsed for recording the different 3D arrays.
Twenty two protìles were record ed both in transversal anel
longituelinal orientation using a mixed Wenner-Schlumberger
an-ay, giving up to six thousand apparent resistivity values.
AIso, for 3D acquisition the main technical problem
affecting the measurements was causecl by the contact
resistances at the potential electrodes. In fact, we neecl-y small-sizeel electrodes with limited but similar contact
Il SCIENZA E PATRIMONIO CULTURALE DEL MEDITERRANEO
resistances. A good choice was the use 01' disposable Foam
AgiAgCl ECG electrocles (Cosentino et aL, 1999), The large
amount 01' data, produced by multielectrode systems,
requires automated data handling and processing.l'o ohtain a more accurate picture 01' the suhsurt~lCe it is
necessmy to invel1 the apparent resistivity data. The inversion method was based on the smoothness-constrained
least square method. In this method, the subsurface is divided into cells 01' fixed dimensions l'or which the resistivities
are adjusted iteratively until an acceptable agreement
between the input data and the mode! responses is
achieved. It is based on a non-linea l' optimization technique
by least-squares fitting (Loke and Barker, 1996). During the
inversion process the root mean square value 01' the ditTerence between experimental data and updated mode l
response is used as a criterion to assess the convergence.
The second method, EM conductivity mapping, is based on
the application 01' a variable primalY field by means 01' a
loop measuring the resulting fielel in another loop. In spite01' the instrument used, an EM138 l'rom GF Instruments,
gave reliable results in the sectors 01' the cathedral elose tothe main door.
ll1is effect has been justified as a result 01' the high electri
cal resistivity 01' the subsoil in most sectors 01' the cathedralwhich inhibit the electromagnetic induction phenomena.
For this reason this technique was discarded to concentrate
the effot1s on the other methods which provided more significant result<;.
For the Ground Probing Radar survey (GPR) a Subsurt~lCeIntert~lCe Radar System (SIR 3000) manufactured by
Geophysical SU1veySystems, GSSI was used. Two antenna e
with centre frequencies 01' 270 and 100 MHz were used.Most 01' the work used the 270 MHz antenna, because theresolution obtained with the 100 MHz antenna was too low
to be effective.
Appropriate data processing stacking, filtering, migration
and advanced visualization techniques were applied to help
in understanding and interpreting GPR data.In addition, to obtain a significant "picture" 01' the under
ground electromagnetic discontinuities, both 3D data col
lection - along closely-spaced parallel survey lines with suf
ficient spatial sampling - and time-consuming 3D data pro-
Fig. 7 - l'icture showing the record 01' a GI'R profile along the centraInave 01' the cathedral.
cessing were required. This in order to reduce aliasing
problems.
The surface 01' the tempie sU1veyed by a grid 01' profiles
spaced 0.4 m apal1 and a horizontal resolution 01' 0.02 m (50
scans per meter). Due to the ne ed 01' having a greatest resolution on the centrai nave, a perpendicular grid was tracedin order to obtain records in both directions.
The acquisition along the elose parallel profiles allowed the
assembly 01' GPR time slices making easy the corre!ation 01'
anomalies recorded at the sa me time. This proved to be one
01' the most useful data presentations l'or understanding the
nature 01' subsurface structures over large areas at different
depths (Goodman et aL, 1995), Oepths were estimated l'roman approximate velocity analysis based on the geometlY 01'
hyperboles.
RESUI:rS
Preliminary results obtained in this sU1vey give us an idea
01' the archaeological potentiality 01' the anomalies after pro
cessing geophysical data. One 01' the main results is that the
erection 01' the building 01' the Medieval Cathedral was car
ried out without completely removing the existing elementsresting on the bedrock.
The anomaly, with high resistivity values up to 2000 Q.m,
which appears in the centraI pal1 01' most 01' the 20 ERT
profiles is interpreted as remains 01' the Augustus tempIebasement (Figure 8).
INDAGINI E DIAGNOSTICA.
Dopth Ihrlltion 5 Abs. orror : 2.9 t9.9 8.0
9.1259.676
l. 3'1
2.152.623.13
3.69
1f.31
16.0 32.0 '10.9
,..
Unit electrode spllcing 0.500 •.
Unit eIectrode spaeing 9.589 •.
..119.932.9
Inverse "odel Resistivi ty Section____.D.~.CO _59.9 811.5 1113 21f1 1f08 689 1165 1969
Resistivity in oh•.•
2.152.623.13
3.69
If .31
Invor •• Hodei Reoiotivity Soction_____ D_C __ o _59.9 8'1.5 1'13 2'11 '108 689 1165 1969
Rooiotivity in oh•.•
Depth Iteretion 5 RHS error : 2.1f 7-0.0 8.9 16.0 21f.0
0.125
0.676
1. 31f
Dopth Iteretion 5 RHS error : 1,16 7-0.0 8.9
0.125
0.676
1. 31f
2.152.623.13
3.69
1f.31
16.0 21f.0 32.9 119.8 ..
Inverse "odel Resistivity Seetion_____ DC~.CD ._59.9 811.5 11f3 21f1 IIG8 689 1165 1969
Resistivity in oh•.• Unit eleetrode spacing 9.599 •.
'"Invorse Hodol Rosiotivi ty SocHon_____ D_~ __ D _
5e.a 811.5 1113 21f1 1198 689 11651969Rooistivity in oh•.•
Dopth Itoretion 'I Abo. orror : 9.811 t9.9 8.9
9.125
9.676
l. 311
2.152.623.13
3.69
'1.31
16.9 21f.9 32.e 110.0
Unit oloctrodo opaeing e. 5ee •.
Fig. 8- Inverted 2D sections of the electrical resistivity tomographies record ed along the cathedral showing the almost rectan-gular resistive body
• SCIENZA E PATl{IMONIO CULTURALE DEL MEDITERRANEO
Using a GPR analysis, the exisrence 01' an archaeologi
cal stratigraphy is asslImed and the analysis 01' the data
suggested clepth alterations or differences between the
centraI ancl the lateral naves, as well as between thecentraI nave ancl the main entrance to the medieval tem
pie.
A generai characteristic al' the surveyecl area is the good
penetration 01' the electromagnetic energy, 100 ns corre
sponcling to a depth 01' about 4.0 m when a mean veloc
ity vaille of 0.08 m/ns is lIsed. This is essentially due to
the physical characteristics 01' the materials lIsed far the
construction 01' the tempie (limestone), which have high
resistivity values and therefore dissipate the EM energy
only slightly.
In spite of the clarity 01' some of the described struc
tures, it musr be pointecl out that their vertical projec
tions are irregular. This wOlllcl indicate a reuse 01' preex
isting elements for the erection of the bllilcling' ancl anirregular conclition 01' preservation.
CONCLUSIONS
The effectiveness or the different geophysical methocls
in mapping the archaeological features in Tarragona'sCatheclral has been confirmecl. The 20 ancl 30 moclels
obtainecl uncler the Catheclral 01' Tarragona will play an
important role in archaeological investigations since
they furnish a synthetic view 01' the location ancl sizes 01'
the most important structures in the area.The results indicate that the lise 01' flat-base electrocles
insteacl of standard pointecl electrocles - is a velY gooclalternative in sites where the latter can not be nailed. It
provicles the aclvantage al' fully nonclestructive applica
tion and the expansion 01' using geoelectrical methocls inenvironments that otherwise we woulcl never consicler.
The structure of the tempIe basement seems to be
revealecl both using 20 ancl 3D electrical imaging tech
niques. Furthermore, the anomalous areas cletectecl by
the clifferent geophysical techniques are velY consistent.
ti
resistivity (ohm.m)-y-.,~o 100 200 300 400 500 600 700 800 900 1000
Fig. 9- 3D image of the high resistive anomaly detected under the centrai paI1 of the Cathedral.
ACK1\OWLEl)GEME1\TS
The allthors are indebted to jallme Plljol (Archbishop ofTarragona's Cathedral), josep Martl (Diocesan Delegate forHeritage), Francesc Gallart (Dea n of the Bishop's Chapter) andIsabel Rodà (Oirector of the Catalan Institllte for ClassicalArchaeology).
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INDAGINI E DIAGNOSTICA •
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A. CASAS, Y. OfAZ, M. HIMI, Department of Geochemistry,Petrology and Applied Geology - University of Barcelona SPAIN
P.L. COSENTINO, G. FIANOACA, R. MARTORANA,Department of Chemistry and Physics of the Earth andApplications - University of Palermo - ITALYE. GAR.cfA, M. LAFUENTE, R. SALA, SOT - Prospecci6Arqueològica. Sant Cugat del Vallès. Barcelona - SPAIN
j.M" MACfAS, Catalan Institute for Classica I Archaeology.Tarragona - SPAIN
j. MENCHON, Municipality of Tarragona. Tarragona - SPAINA. MUNOZ, AND I. TEIXELL, Biblical Museum - Archbishopyof Tarragona - SPAIN