107
Alexande SOKOLICEK(*), Guglielmo GRECHI(**), Alexand a TANNER(***), Lydia BERGER(*),
S e ano RIVELLINO(**), Ma ia MONTAGNESE(**), Gian Ma co MARMONI(**),
Yawa HUSSAIN(**) & Sal a o e MARTINO(**)
(*)Pa is Lod on Uni e si y o Salzbu g - Depa men o Classics - Salzbu g, Aus ia
(**)Sapienza Uni e si y o Rome - Depa men o Ea h Sciences and Resea ch Cen e o Geological Risks (CERI) - Rome, I aly
(***)Technical Uni e si y o Be lin - Depa men o Building A chaeology and He i age Conse a ion - Be lin, Ge many
Co esponding au ho : alexande [email p o ec ed]
ENGINEERING-GEOLOGICAL AND GEOPHYSICAL SURVEYS
FOR ARCHAEOLOGICAL RISK ASSESSMENT IN VIEW OF MITIGATION
MEASURES AT AEGINA KOLONNA, GREECE
EXTENDED AbSTRACT
Il si o a cheologico di Aegina Kolonna, un impo an e pa imonio cul u ale in G ecia, occupa un p omon o io cos ie o ed è minaccia o
da nume osi a o i ambien ali e geologici, a cui la con inua e osione cos ie a, la sismici à locale e la di usa ins abili à delle sca pa e
cos ie e che delimi ano il p omon o io. Il p og essi o a e amen o delle sca pa e che bo dano il p omon o io ha già causa o, in a i, la
pe di a i e e sibile di pa e dei beni a cheologici non anco a sca a i, comp ome endo se e amen e la p ese azione del si o. Nell’ambi o
del P oge o Eu opeo TRIQUETRA (Toolbox o assessing and mi iga ing Clima e Change isks and na u al haza ds h ea ening cul u al
he i age), è s a o spe imen a o un app occio in e disciplina e che in eg a geologica applica a, geo isica e a cheologia pe la alu azione
dei pe icoli geologici e della ulne abili à del si o. Il p og essi o a e amen o della linea di cos a dell’a ea di s udio è de e mina o da una
complessa in e azione di a o i geologici e ambien ali. L’asse o s a ig a ico locale, che ede a io a e una o mazione calca eni ica qua-
e na ia so appos a ad a gille plioceniche, app esen a il a o e p edisponen e p incipale del p ocesso di a e amen o, essendo il mo o e
di una dinamica di c eep guida a da p ocessi iscoplas ici, che a o isce lo s iluppo di espandimen i la e ali esponsabili del p og edi e dei
p ocessi di ins abili à delle pa e i cos ie e. Nell’ambi o delle a i i à p e is e dal p oge o TRIQUETRA, è s a a condo a una campagna
di indagini geologico- ecniche e geo isiche, inalizza a alla icos uzione del modello geologico- ecnico dell’in e o p omon o io. Ol e al
ile amen o geologico dell’a ea, sono s a e esegui e 26 misu e di umo e sismico ambien ale a s azione singola pe suppo a e la icos u-
zione del modello geologico di si o e alu a e la ispos a sismica locale. I isul a i o enu i hanno e idenzia o l’esis enza di due in e alli di
equenze di isonanza ondamen ali di si o a 0.4-0.7 Hz e 8-25 Hz, che sono indica i i di po enziali e e i di ampli icazione s a ig a ica
(i.e., 1D) del mo o sismico do u i ispe i amen e a un ele a o con as o d’impedenza con il subs a o sismico p o ondo e a possibili con-
as i a gli s a i più supe iciali. Inol e, dall’analisi del compo amen o dinamico dell’unica colonna ad oggi in eg a del Tempio di Apol-
lo, è s a o possibile iden i ica e due equenze di isonanza s u u ale a 5.1 e 8.2 Hz. Ques e equenze sono so apponibili alla equenza
di po enziale ampli icazione sismica di si o e dunque non possono esse e esclusi e e i di danneggiamen o s u u ale in caso di scuo imen o
sismico. Ol e alla alu azione della pe icolosi à geologica locale, il p oge o TRIQUETRA si concen a anche sullo s iluppo di s a egie
pe la conse azione dei si i a cheologici di in e esse cul u ale. Pe il caso di s udio di Aegina Kolonna, nell’a ea dei cosidde i sobbo ghi
p eis o ici dell’es , i p eceden i in e en i di es au o del pa imonio s o ico hanno p e is o l’u ilizzo di mal e a base di cemen o che nel
empo si sono de e io a e comp ome endo la s abili à s u u ale delle ope e e causando pe di a di ma e iale. Nell’ambi o del p oge o sono
s a e implemen a e nuo e misu e conse a i e ol e a s abilizza e il pa imonio sca a o. L’analisi scien i ica a cheologica e la documen-
azione sis ema ica dello s a o di deg ado delle s u u e, a l’al o e e ua a median e o og amme ia ad al a isoluzione, o ni ano una
base accu a a pe gli in e en i successi i. Le mal e cemen izie de e io a e sono s a e sos i ui e con mal e a base di calce, più compa ibili
con i ma e iali o iginali e in g ado di ga an i e una maggio e du abili à. Inol e, pe mi iga e il ischio di e osione e danneggiamen o delle
ondazioni mu a ie, è s a o ealizza o un consolidamen o pa ziale, segui o da un in e o delle incee di sca o più p o onde, s abilizzando
e p o eggendo le s u u e. In ine, è s a o implemen a o un p og amma di moni o aggio annuale delle s u u e es au a e, inalizza o alla
alu azione dell’e icacia delle soluzioni ado a e e all’e en uale de inizione di ul e io i s a egie conse a i e. Dai isul a i o enu i eme ge
come l’u ilizzo di un app occio olis ico e si o-speci ico sia necessa io pe la co e a ges ione e alo izzazione del pa imonio s o ico e cul-
u ale espos o ai ischi geologici. Il p oge o TRIQUETRA ha pe ques o si o l’ambizioso obie i o di in eg a e l’analisi della pe icolosi à
connessa a a o i geologici con l’u ilizzo di ecniche di es au o e conse azione pe s iluppa e s a egie di conse azione sos enibili del
pa imonio a cheologico cus odi o nel si o di Aegina Kolonna.
I alian Jou nal o Enginee ing Geology and En i onmen
www.ijege.uni oma1.i
IJEGE, Special Issue 1 (2025): 107-122, DOI: 10.4408/IJEGE.2025-01.S-08
E-ISSN 2035-5688 | ISSN 1825-6635 / ©Au ho (s)
108 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
A. SOKOLICEK, G. GRECHI, A. TANNER, L. bERGER, S. RIVELLINO, M. MONTAGNESE, G. M. MARMONI, Y. HUSSAIN & S. MARTINO
AbSTRACT
The a chaeological si e o Aegina Kolonna, a p ominen
cul u al he i age landma k in G eece, is inc easingly h ea ened
by geological haza ds, including coas al e osion, seismic
ac i i y, and slope ins abili ies. The p og essi e e ea o he
calca eni e sea cli s has al eady led o he loss o unexca a ed
his o ical emains, posing a se e e isk o he si e’s long-
e m p ese a ion. Wi hin he amewo k o he TRIQUETRA
(Toolbox o assessing and mi iga ing Clima e Change isks and
na u al haza ds h ea ening cul u al he i age) Eu opean P ojec ,
an in e disciplina y app oach ha in eg a es enginee ing-
geological, geophysical, and a chaeological in es iga ions
has been adop ed o assess si e ulne abili y and implemen
a ge ed mi iga ion s a egies. A comp ehensi e geological
su ey iden i ied he p ima y ac o s d i ing cli ins abili y,
while ambien seismic noise measu emen s helped cha ac e ize
he subsu ace condi ions and assess local seismic ampli ica ion
e ec s. The s uc u al s abili y o key a chaeological elemen s,
such as he las s anding column o he Apollo Temple, was also
e alua ed, e ealing esonance equencies in he ange 5-8 Hz,
which may in luence i s seismic ulne abili y.
In addi ion o haza d assessmen , he TRIQUETRA p ojec
ocuses on he i age conse a ion o his si e, pa icula ly o
he no heas e n p ehis o ic se lemen . Pas es o a ion e o s
elied on cemen -based mo a s, which ha e de e io a ed
o e ime, leading o s uc u al ins abili y. To add ess his,
new in e en ions include de ailed documen a ion, he
eplacemen o deg aded ma e ials wi h lime-based mo a s,
pa ial back illing o s abilize exposed ounda ions, and he
implemen a ion o long- e m moni o ing s a egies. These
measu es aim o enhance s uc u al esilience while adhe ing
o in e na ional he i age conse a ion guidelines.
This s udy unde sco es he necessi y o a holis ic app oach
o cul u al he i age managemen , demons a ing how scien i ic
esea ch and es o a ion p ac ices can be in eg a ed o mi iga e
geological and en i onmen al isks and ensu e he sus ainable
p ese a ion o a chaeological si es.
Keywo ds: Aegina Kolonna, cul u al he i age, isk assessmen , geology,
si e conse a ion
INTRODUCTION
The wa e s a ound Cape Kolonna, which is loca ed in he
no h-wes o he island o Aegina in he Sa onic Gul in G eece,
a e eache ous, and we e ea ed as such al eady in an iqui y:
Pausanias, he G eek a ele o he 2nd c. AD, called Aegina as he
mos di icul island in G eece o access “ o i is su ounded by
sunken ocks and ee s which ise up” (Paus. 2, 29, 6). In mode n
imes, he dange o access is le e ed by echnology, bu he
wa e s a e s ill a h ea o Kolonna. The small peninsula, which
co e s an a ea o app oxima ely 3.5 hec a es, is home o he mos
signi ican a chaeological si e in Aegina (Fig. 1).
The wes e n pa o he si e is ex emely exposed o he
en i onmen al s esso s abo e he sho e (Fig. 13); s eep cli s
ma k he bounda y o he a chaeological zone, which in an iqui y
was la ge han oday. The ongoing p ocess o e osion causes
he agmen a ion o he cli ace; unexca a ed a eas o he
his o ical si e ha e been los al eady, and o he s a e in dange
o being se e ely damaged. O e he pas ew decades, he e has
been a disce nible impac o na u al haza ds on he a chaeological
emains, as e idenced by sys ema ic obse a ions. This a ec s
no only walls exposed o p ecipi a ion and signi ican daily
and seasonal empe a u e a ia ions, bu also he geological and
cul u al laye s ha we e exca a ed and subsequen ly b oke o he
s eep cli in he wes (Fig. 2, Fig. 13).
The e o e, he p og essi e e ea o he calca eni e cli s a
Aegina Kolonna ep esen s a c i ical geological p ocess ha has
led o he loss o a chaeological emains and con inues o h ea en
he in eg i y o his he i age si e. This phenomenon esul s om
he combina ion o p edisposing ac o s ela ed o he geological
se ing o he Aegina Kolonna p omon o y, wi h p epa a o y
ac ions linked o he mass ock c eep p ocess as well as wi h
igge s ela ed o sea wa e impac s agains he cli and local
seismici y. Fu he mo e, he ole o loods connec ed o in ense
ain all e en s as well as he possible o e aking o he sea cli by
anomalous wa es, such as hose connec ed o possible sunamis,
does no appea o be negligible. Fo his se o ac o s, he case
s udy o he Aegina Kolonna p omon o y ep esen s an in e es ing
example o a combined geohaza d (mul iple haza d) as well as
o a possible “domino e ec ” connec ed o igge ing causes
(cascading haza d). In bo h cases, he esul ing haza d scena ios
consis o he o e lapping o e ec s in he p omon o y a ea ha
in ensi y he le el o damage o he a chaeological s uc u es
Fig. 1 - O hopho o o Aegina Kolonna in 2012
109
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ENGINEERING-GEOLOGICAL AND GEOPHYSICAL SURVEYS FOR ARCHAEOLOGICAL RISK ASSESSMENT AND PREVIOUS MITIGATION
MEASURES AT THE AEGINA KOLONNA, GREECE
p esen he ein. Such a complex geological con ex combining
li ho echnical he e ogenei y, s uc u al discon inui ies, and
e osional mechanisms is esponsible o accele a ing he cli
deg ada ion, de e mining i s e ea and p og essi e demoli ion.
Unde s anding he main d i e s o his p ocess is undamen al
o assessing he local ulne abili y and de eloping e ec i e
p ese a ion s a egies. To his aim, du ing he ea ly s ages
o he TRIQUETRA p ojec , he geological condi ions o
each pilo si e ha e been cha ac e ized o de e mine he mos
signi ican geological haza d a ec ing he exposed cul u al
he i age. This was accomplished o he Aegina Kolonna case
s udies by de eloping a “Geohaza d Se e y Cha ” (GSC), a
ma ix-based ool ha assesses and ca ego izes he se e i y o
geological haza ds (Fig. 3). A GSC includes wo componen s:
ype o p ocess and ime o ecu ence. By combining hese wo
componen s, he GSC assigns an in ensi y le el o each po en ial
geohaza d scena io, ca ego izing hem in o p ede ined se e i y
ca ego ies. This s uc u ed amewo k aids in geological isk
assessmen , p io i izing haza ds, and de eloping mi iga ion
s a egies o cul u al he i age si es and in as uc u e ( o mo e
in o ma ion, see Ioannidis e alii, 2024).
The geological haza ds cha ac e izing Aegina Kolonna a e
s ongly ela ed o he geo-s uc u al se ing o he Sa onic Gul
and o he s a ig aphic se ing o he p omon o y. Enginee ing-
geological and geophysical su eys we e pe o med o cons ain
he local geological se ing and c ea e a base laye o a mo e
comp ehensi e geological haza d and isk assessmen analysis.
This s udy a emp s o es ablish he necessa y g oundwo k o
a si e-speci ic haza d assessmen by cha ac e izing he local
geological amewo k and iden i ying hose ac o s con olling he
cli e ea p ocess. Wi hin he amewo k o he TRIQUETRA
p ojec , hese indings will con ibu e o a b oade me hodological
app oach aimed a de eloping p edic i e models o si e
deg ada ion and de ining a ge ed mi iga ion s a egies. The esul s
will suppo long- e m conse a ion planning and a chaeological
si e managemen in o med by si e-speci ic geological isk.
Geological and geomo phological se ing
The island o Aegina co e s an a ea o abou 87 km2 and has
57 km o coas line. Aegina lies a he no hwes end o he Sou h
Aegean Volcanic A c (Mou zas & Kolai i, 2013), which spans
om he Sa onic Gul in he wes o he island o Nisy os in he
eas (Elbu g & Sme , 2020). The island is one o he a c’s olcanic
cen e s, whe e olcanism i s began (Vougioukalakis e alii,
2019). This olcanic a c was o med by he subduc ion and ollback
o he A ican pla e benea h he Aegean mic opla e (Papazachos &
Comninakis, 1971; Pe & Pipe , 1972; Royden & Papanikolau,
2011; Joli e e alii, 2013; Fou akis e alii, 2020) (Fig. 4a, b).
The Sa onic Gul is a ec ed by an N-S ex ensional back-a c
ec onism ha educes he c us hickness o 20 km and allows
he man le ma e ial o ascend (Geo giou e alii, 2021). The
Sa onic Gul a ea has gene ally low seismici y, hough s ong
ea hquakes, bo h ecen and his o ical, ha e occu ed on he
gul ’s no he n edge (Mak opoulos e alii, 2012). This a ea
has a complex aul pa e n (Papanikolau e alii, 1988): ac i e
no mal aul s as well as s ike-slip aul s, ha e o med due o
subsidence (Geo giou e alii, 2021). The island o Aegina is
domina ed by ex ensional ec onics, which ha e caused upli
and subsidence, esul ing in he o ma ion o ho s and g aben
s uc u es in addi ion o he emplacemen o magma.
Fig. 2 - B oken a chaeological emains in he wes e n cli : a) well b) walls c) land loss be ween 2012 (ou e ed line) and 2024 (inne ed line)
Fig. 3 - Geohaza d Se e i y Cha (GSC) de eloped o he
TRIQUETRA case s udy o Aegina Kolonna
110 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
A. SOKOLICEK, G. GRECHI, A. TANNER, L. bERGER, S. RIVELLINO, M. MONTAGNESE, G. M. MARMONI, Y. HUSSAIN & S. MARTINO
The geological basemen o he island is cons i u ed o
Mesozoic limes ones and Eocene lysch, which a e only isible in
he cen al-no he n pa o he island (Do ais & Sh ine , 2002).
La e Messinian ansg essi e conglome a es can be ound abo e
Eocene lysch in some no he n coas ou c ops (Die ich e alii,
1993). The i s olcanic phase (“Daci ic phase”; Die ich e
alii, 1993) s a ed be ween 4.7 and 4.3 Ma (F ancalanci e alii,
2005), ini ially o e lapping he basemen wi h hyodaci ic ashes
and pumice. Mo e ecen andesi ic-daci ic la a lows o med he
cen al pa o he island (Mou zas & Kolai i, 2013). Be ween
3.0 and 2.1 Ma, a low- a e e up ion pe iod likely occu ed
(F ancalanci e alii, 2005), be o e and du ing which shallow
ma ine sedimen s accumula ed. This Pliocene sedimen a y
succession consis s o sil y clays and ma ls. The p edominan
ea u e is he occu ence o yellow o g eenish ma ls, ich in
ine-g ained sandy in e cala ion. The g eenish colo s a e he
exp ession o a high con en o chlo i e, epido e, and se pen ine
mine als (Die ich e alii, 1993). A e his and du ing he second
Fig. 4 - a) Geog aphic loca ion o he Sa onic Gul ; b) loca ion o he Sou h Aegean Volcanic A c wi h he p incipal olcanoes and c) geological map
o he island o Aegina indica ing he s udy a ea ( ec angle). [mod. a e Do ais & Sh ine (2002) and Mou zas & Kolai i (2013)]
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i 111
ENGINEERING-GEOLOGICAL AND GEOPHYSICAL SURVEYS FOR ARCHAEOLOGICAL RISK ASSESSMENT AND PREVIOUS MITIGATION
MEASURES AT THE AEGINA KOLONNA, GREECE
olcanic phase (“Andesi ic phase”; Die ich e alii, 1993), mino
amoun s o py oclas ics and lows o basal ic andesi es, high-
alumina basal s, and andesi es we e p oduced, hus o ming he
sou h pa o he island. This was ollowed by subsidence o he
no h pa o he island and he deposi ion on he no h coas s o
ha d, whi e, sandy–ma ly limes one o ma ine o igin (Mou zas
& Kolai i, 2013) (“Po os Fo ma ion”) (Fig. 4-c).
Aegina Kolonna is a mino p omon o y, eaching a maximum
ele a ion o abou 15 m abo e sea le el, ha g adually me ges
wi h he inland while exhibi ing a qui e s eep sea cli on i s
wes e nmos sec ion ( ha eaches a maximum heigh o abou
8 m). The dominan mo phogene ic con ol on he land o ms in
he p omon o y is ep esen ed by he g a i y-induced p ocesses
(landslides) and by he sea. Many ock blocks a e p esen below
he sea cli , depic ing a p edominan p ocess in e ms o cli ’s
edge e ea and geological isk. The main p ocess ha occu s
in he a ea is he la e al sp eading caused by he peculia
s a ig aphic se ing (s i Qua e na y calca eni e o e laying
duc ile Pliocene clays). Such heological con as is esponsible
o he de o ma ion p ocess ha cu en ly a ec s he wes e n
po ions o he p omon o y and is e lec ed in ock oppling
and alls (Hung e alii, 2014) ha pe iodically a ec he cli .
The sea, h ough he p ocess o wa e e ac ion, con ibu es o
he e olu ion o he cli . The ene gy o he sea wa es ends o
concen a e a he wes e nmos po ion o he p omon o y, causing
he e osion o he ma ly ho izon and he c ea ion o a basal no ch.
His o ical and a chaeological ou line o Aegina
The island o Aegina is loca ed in he middle o he Sa onic
Gul , in p oximi y o Pi aeus, A hens and A ica ( om abou 19
km), o Salamis (app . 12 km) and e en close o he peninsula
o Me hana on he Peloponnese in he sou h-eas (app . 8 km). I s
icini y o he mainland, coupled wi h i s ad an ageous access o
he Aegean Sea, has a ac ed people o se le since he Neoli hic
pe iod (a leas since he 4 h millennium BCE). Cape Kolonna, on
he well-p o ec ed wes e n side o he island, wi h he wo na u al
ha bou bays, and endowed wi h a e ile hin e land, o e ed
he island a pa icula ly sui able en i onmen o habi a ion.
Consequen ly, i is home o he la ges o i ied B onze Age
se lemen on he island, da ing back o he 3 d and 2nd mill BCE.
I s economic p ospe i y is e lec ed in he con inuous expansion o
he se lemen eas wa ds om he o i ied cen e (Gauss, 2010). In
his o ic imes (7 h c. BCE - 3 d c. AD) Kolonna housed a p ominen
sanc ua y wi h a well- isible emple, buil a ound 530/520 BC.
The cons uc ion o he la ge cen al Do ic pe ip e al emple
(so-called emple o Apollo) wi h i s su ounding emenos
wall ep esen s a highligh in he his o y o Kolonna (Fel en,
2007). I s massi e ounda ions a e oo ed in he walls o he
ea lies se lemen e ealing he in e wined and complica ed
his o y o he si e. The appella ion ‘Colonna’ was bes owed by
he Vene ian sailo s, who u ilized he wo emaining columns
as a poin o o ien a ion, o which one collapsed in he 19 h c.
Nowadays, he las column o he emple domina es he hill. I
is isible om all di ec ions and hus gi es he cape i s name.
Towa ds he end o he 6 h c. AD, new se le s om
Co in h a i ed in Aegina and ans o med he si e in o a new,
ea ly Byzan ine own ha su i ed un il app oxima ely AD
1000 (Pennas, 2005; Fel en, 2007). The building ac i i ies
unde aken by he mos ecen se le s esul ed in signi ican
dis up ion o he olde a chi ec u al emains and s uc u es.
They le elled he si e and eused olde s ones and componen s
(spolia) o hei new buildings. This has had a p o ound
e ec on he a chi ec u al emains, wi h he s uc u es o he
sanc ua y in pa icula being se e ely a ec ed.
The si e has been s udied in he p ojec Aegina Kolonna,
i s exca a ions going back o he 19 h c. The Uni e si y o
Salzbu g has ca ied ou exca a ions o he a chaeological si e
on an annual basis since 1966; he cu en ocus o esea ch
concen a es on he B onze Age se lemen and he Byzan ine
occupa ion as well as on he digi iza ion o he exca a ion
(p ojec : “Mapping Kolonna” o suppo geophysical
in es iga ions and he modelling o he si e, Spo n e alii 2017,
Sokolicek, 2023; see: www.aegina-kolonna.a ).
The Inne Subu b o he p ehis o ic se lemen on he hill o
Aegina Kolonna was one o he i s a ge s o a chaeological
in e en ions a he si e in he la e 19 h and ea ly 20 h cen u ies.
Exca a ions in his a ea we e mainly ca ied ou be ween he
Fi s and Second Wo ld Wa s and con inued un il he ea ly
1980s (S ais, 1895; Wol e s, 1925; Spo n e alii, 2017).
Wo k on he si e was comple ed a ound 1990 wi h pa ial
consolida ion using cemen mo a .
This Inne Subu b was buil in he Middle B onze Age ou side
he exis ing se lemen . I consis s o a se ies o ooms buil agains
a new o i ica ion wall, some o which had been p ese ed o he
le el o he doo lin el (Fig. 5a). As is cha ac e is ic o he B onze
Age, hey a e buil o local ubble s ones and clay mo a (Fig. 1;
Fig. 5a). This ype o cons uc ion is e y sensi i e o he elemen s,
especially ainwa e , which washes ou he join s and leads o
ins abili y o he walls. Unsu p isingly, al eady a ew decades
a e he exca a ion, in he 1920s, pa s o he cons uc ions
we e los , leading o he p esen si ua ion. The ubble walls we e
o iginally co e ed wi h a p o ec i e laye o lime plas e , pa s o
which a e s ill p ese ed in a oom wi h a po e y kiln. This oom
is co e ed by a mode n po ch oo , a measu e ca ied ou du ing
a p e ious es o a ion a ound 1990 (Fig. 5b).
ENGINEERING-GEOLOGICAL AND GEOPHY-
SICAL SURVEYS
In he amewo k o he TRIQUETRA p ojec , enginee ing-
geological su eys o he s udy si e we e ca ied ou in July
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A. SOKOLICEK, G. GRECHI, A. TANNER, L. bERGER, S. RIVELLINO, M. MONTAGNESE, G. M. MARMONI, Y. HUSSAIN & S. MARTINO
he assessmen o join dis ibu ion, pe sis ence, and in illing
condi ions. A scanline su ey was also conduc ed in sec o s
whe e he calca eni e was mos exposed, allowing o he
quan i a i e e alua ion o he ock mass ac u ing condi ions.
In addi ion o he enginee ing-geological su eying, single-
s a ion ambien seismic noise measu emen s we e aken a 26
di e en loca ions, co e ing he en i e a chaeological a ea (Fig.
6a), o cons ain he subsu ace geological se ing by iden i ying
undamen al si e esonance equencies ( 0) h ough he HVSR
echnique (Nogoshi & Iga ashi, 1970; Nakamu a, 1989). The
HVSR analysis is pa icula ly well-sui ed o si e cha ac e iza ion
when ma ked seismic impedance con as s exis be ween low
shea -wa e eloci y laye s and he unde lying seismic bed ock,
and peaked equencies in he HVSR unc ion can be in e p e ed
as esonances o he so su ace laye s (Bonne oy-Claude e
alii, 2006; Iannucci e alii, 2018). Fo each measu ing s a ion,
he ambien ib a ions we e eco ded o 1-hou a a sampling
equency o 200 Hz using a SARA SL06 h ee-componen
elocime e (2.0 Hz nominal equency) equipped wi h an in-buil
2023 and 2024 o iden i y and delinea e he main enginee ing-
geological uni s and geomo phological ea u es o he Aegina
Kolonna p omon o y. The ield in es iga ions ocused on
econs uc ing and mapping he geological con ac s be ween
he s i Pleis ocene calca eni es and he unde lying de o mable
ma ls, a li hological con as ha plays a undamen al ole in he
slope ins abili ies a ec ing he wes e n sec o o he p omon o y.
In his a ea, ins abili y mechanisms - mainly ock alls and
block opples - a e ac i ely d i ing he e ea o he cli edge,
he eby h ea ening he in eg i y o he a chaeological emains.
The in e ac ion be ween s uc u al discon inui ies and wa e-
induced e osion is p omo ing he p og essi e ailu e o he
cli , leading o basal unde cu ing and no ch o ma ion
in he ma ly subs a um, which u he des abilizes he
o e lying calca eni e cap- ock. In his amewo k, a de ailed
enginee ing-geological ield su ey was ca ied ou mapping
and cha ac e izing he ou c opping geological uni s. A
geomechanical cha ac e iza ion o he Pleis ocene calca eni e
was pe o med ollowing ISRM (2007) s anda ds, including
Fig. 5 - Inne Subu b wi h oom wi h po e y kiln om he wes . a) a ound 1900 (Pho o a chi e o he Ge man A chaeological Ins i u e A hens, D-DAI-
ATH-Aegina-0017); b) in 2024
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ENGINEERING-GEOLOGICAL AND GEOPHYSICAL SURVEYS FOR ARCHAEOLOGICAL RISK ASSESSMENT AND PREVIOUS MITIGATION
MEASURES AT THE AEGINA KOLONNA, GREECE
24-bi digi ize . In he amewo k o he TRIQUETRA P ojec , a
dedica ed MATLAB oolbox was de eloped o p ocess ambien
ib a ion da a and e ie e H/V unc ions o each eco ding s a ion.
The da a p ocessing wo k low ollowed a sys ema ic app oach
o ensu e he eliabili y o he compu ed spec al a ios. A i s ,
basic ime se ies and spec al analyses we e pe o med o e alua e
da a quali y and e i y he absence o signi ican dis u bances in
he eco dings (e.g., an h opogenic noise, ea hquakes, and s ong
winds). A e da a alida ion, p ep ocessed was conduc ed on all
signals by emo ing he mean, linea end, and co ec ing o he
ins umen esponse ia spec al di ision, inally band-passing
da a be ween 0.05 and 50 Hz. Following, he Welch’s me hod
(Welch, 1967) was used o es ima e powe spec al densi ies
(PSD) and Fou ie ampli ude spec a (FAS), wi h s acked Fas
Fou ie ans o ms (FFT) o 60 s Hanning- ape ed windows
wi h 50% o e lap o educe a iance (Fig. 5b). To u he educe
spec al a iabili y, each FAS was smoo hed using he Konno-
Ohmachi il e wi h a b- alue o 40. The ho izon al componen s
we e a e aged using he geome ic mean (Ba d, 2005), and he
HVSR unc ions we e compu ed as he a io be ween he a e age
ho izon al and e ical FAS o each window (Eq. 1).
(1)
The a e age HVSR unc ion and i s s anda d de ia ion
we e compu ed o e all windows o p o ide a obus es ima e
o si e-speci ic spec al ampli ica ion cha ac e is ics (Fig. 6c).
Finally, o in es iga e he di ec ionali y o he H/V unc ions, he
H/V a ios we e compu ed o mul iple azimu hal o ien a ions
by sys ema ically o a ing he ho izon al componen s o each
s a ion (Fig. 6d). A s ong azimu hal a ia ion may be he i s
indica ion o nonuni o m sou ce dis ibu ions and/o he p esence
Fig. 6 - a) Sa elli e iew o he a chaeological a ea o Aegina Kolonna wi h he loca ion o all ambien seismic noise measu emen s a ions. b) Example
o Fou ie Ampli ude Spec a (FAS) o s a ion EG06, showing spec al ampli udes o he No h-Sou h (NS), Eas -Wes (EW), and e ical
(UD) componen s. c) Co esponding HVSR unc ion o EG06, wi h he mean HVSR cu e ( ed) and s anda d de ia ion (black dashed line).
d) HVSR o a e analysis o EG06, illus a ing he di ec ionali y o he HVSR a io as a unc ion o equency, whe e azimu hal a ia ions
highligh he po en ial pola iza ion o si e esonance. e)–h) Composi e plo s showing esul s o addi ional s a ions (EG07, EG18, EG20, and
EG25), showing dominan esonance peaks and hei di ec ional cha ac e is ics
114 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
A. SOKOLICEK, G. GRECHI, A. TANNER, L. bERGER, S. RIVELLINO, M. MONTAGNESE, G. M. MARMONI, Y. HUSSAIN & S. MARTINO
di ec ion/dip, Fig. 7a): J1 (308°N/74) and J2 (158°N/87). In
pa icula , he o ien a ion o J1 ma ches a mapped aul o sho e
o he Kolonna p omon o y (Fig. 4c), and i is hus likely
ela ed o ha s uc u al lineamen .
Resul s om ambien seismic noise measu emen s helped
cons aining he hickness o he iden i ied enginee ing-
geological uni s and p elimina y assessing he si e-speci ic
seismic esponse o he in es iga ed a ea. Resul s om HVSR
analysis e eal a consis en and p ominen peak ac oss all
s a ions in he equency ange 0.4-0.7 Hz (Fig. 6, 7). This
HVSR peak was in e p e ed as esul ing om a e y deep
seismic impedance con as be ween he Eocene lysch o
Mesozoic limes one, ha cons i u es he seismic bed ock, and
he Pliocene Clay uni ou c opping in he a ea. This HVSR
peak ea u es a b oad o “pla eau-like” shape (Fig. 6e-h),
gene ally o igina ed by seismic noise wa e ield di ac ion,
ha sugges s he exis ence o an inclined o i egula con ac
be ween he so -soil deposi s and he unde lying seismic
bed ock (Uebayashi, 2003). No signi ican di ec ionali y is
obse ed in he HVSR unc ions wi hin his equency ange,
hus sugges ing a dep h-con olled (i.e., s a ig aphic) o 1D
seismic esponse model o he a ea. Besides, all s a ions
loca ed abo e he Calca eni e uni show HVSR unc ions ha
a e cha ac e ized by a sha p ampli ude d op up o alues <
1 in he equency ange 1-10 Hz. This ma ked dec ease in
he HVSR ampli ude esul s om he highe ampli ude o
he e ical componen ela i e o he wo ho izon al ones,
sugges ing he exis ence o a shea -wa e eloci y con as
be ween he so clays and he o e lying s i calca eni e uni ,
ha can also be app ecia ed in co espondence o elu ial-
collu ial and an h opic deposi s. This e idence u he helped
econs uc he enginee ing-geologic model o he s udy a ea
by cons aining he spa ial dis ibu ion o he Calca eni e uni .
I is wo h no ing ha some s a ions highligh ed clea peaks
in he HVSR unc ions in he equency 8-25 Hz (Fig. 6e,
7b). Al hough hese peaks a e no consis en ac oss he en i e
p omon o y a ea, we in e p e ed hem as de i ing om local
esonances o shallow deposi s (e.g., Elu ial-Collu ial and
An h opic uni s). Simila ly, a ew s a ions close o he wes e n
edge o he p omon o y show HVSR peaks a equencies
highe han 40 Hz ha can be po en ially associa ed wi h
local esonances o calca eni e blocks pa ly dislodged om
he cli by sub e ical ac u es.
These esul s de i ing om passi e seismic in es iga ions based
on en i onmen al seismic noise eco dings, allow us o associa e a
concep ual model o seismic esponse o he p omon o y o Aegina
Kolonna which, in ag eemen wi h Ma ino (2024), a ies om
“dep h con olled”, in he inne mos a ea o he p omon o y, o
“ olume con olled”, in he pe ime e a ea. In he i s case, he
s a ig aphic esonance connec ed o he geological se ing o he
o subsu ace geological he e ogenei ies (Wa hele , 2020),
p o iding p elimina y insigh s in o si e-speci ic cha ac e is ics.
Besides conduc ing ambien seismic noise measu emen s o
cha ac e ize he local seismic esponse o he p omon o y, we also
eco ded ambien ib a ions a he base o he las s anding column
o he Apollon Temple. A seismome e was deployed close o he
column’s base and con inuously eco ded ambien ib a ions o
3 hou s, wi h he aim o in es iga ing he dynamic beha io o
he s uc u e. This p elimina y su ey se es as a e e ence o
u u e analyses aimed a assessing i s s abili y and ib a ional
esponse o en i onmen al and seismic exci a ions. Da a we e
analyzed o bo h spec al con en and pola iza ion a ibu es.
Spec al analysis ollowing he al eady desc ibed p ocessing
s eps, ha e been pe o med and he esul ing PSDs we e analyzed
o iden i y spec al peaks po en ially ela ed o esonance modes
o he column. To u he cha ac e ize he iden i ied peaks,
equency-dependen pola iza ion analysis was pe o med on he
da ase (Kope & Hawley, 2010). This echnique can aid in he
in e p e a ion o spec al peaks as esonance modes by allowing
o he ex ac ion o he deg ee o pola iza ion, pola iza ion
azimu h and dip wi h espec o he ho izon al plane.
MAIN OUTCOMES
The de ailed enginee ing-geological su ey allowed
o cons ain he geological and geomo phological se ing
ou c opping o he s udy a ea. A o al o i e enginee ing-
geological uni s we e ecognized ac oss he p omon o y (Fig. 7a):
• Clay uni : he oldes enginee ing-geological uni ou c opping
in he p omon o y and consis s o medium- o-high
consis ency sil y clays and yellow-g eenish ma ls (Lowe
Pliocene-Uppe Pliocene).
• Calca eni e uni : ock mass uni composed o calca eni e
laye s up o 120 cm hick, hin sands one and ma l laye s,
and in e als up o 50 cm hick o poo ly so ed, g ain-
suppo ed b eccias in a sandy-sil y ma ix. Aeolian deposi s
wi h good cemen a ion can also be ound a he op o he uni
(Lowe Pleis ocene). This uni is associa ed wi h he Po os
Fo ma ion and cons i u es he p ima y li hology o ming he
Aegina Kolonna sea cli s.
• Elu ial-Collu ial uni : sil y-clayey deposi s cons i u ed by
wea he ed ma e ial and de i al deposi s anspo ed by shee
wa e s (Olocene).
• Backsho e uni : sandy-sil y ansi ional deposi s ha can be
ound be ween he mainland and he sho eline (Olocene).
• An h opic uni : cons i u ed by bo h he a chaeological
emains and was e deposi s o he di e en a chaeological
exca a ions in he a ea.
The geomechanical cha ac e iza ion o he Pleis ocene
calca eni e e ealed he p esence o h ee join se s, including
sub-ho izon al bedding (J0) and wo s eeply dipping se s (dip
a ea is subs an ially e iden , while in he second case, his e ec is
supe imposed by he speci ic p esence o eigenmodes connec ed o
blocks o ock isola ed by ac u es o ming along he pe ime e o
he sea cli , especially in i s wes e nmos po ion.
The ambien ib a ion da a collec ed a he base o he column
115
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ENGINEERING-GEOLOGICAL AND GEOPHYSICAL SURVEYS FOR ARCHAEOLOGICAL RISK ASSESSMENT AND PREVIOUS MITIGATION
MEASURES AT THE AEGINA KOLONNA, GREECE
allowed us o p elimina y cha ac e ize i s dynamic beha io
(Fig. 7). F om spec al analysis, wo p ominen peaks we e
manually iden i ied a 5.2 Hz ( 1) and 8.1 Hz ( 2), co esponding
o local maxima in he PSDs (Fig. 8a), ha we e in e p e ed as
esonance equencies o he column. In ac , hese equencies
Fig. 7 - a) Enginee ing-geological map o he s udy a ea, showing he main geological uni s, geomo phological elemen s, and ambien seismic noise
measu emen s a ions. The c oss-sec ion aces A-A’-A’’ b) and B-B’ c) a e indica ed in yellow, while he loca ion o he geomechanical
scanline is ma ked wi h a ed s a . Composi e HVSR plo s o selec ed measu emen s a ions ( ed ci cles in panel a) a e shown along bo h
c oss sec ions o highligh he seismic si e esponse. The s e eoplo in he uppe - igh co ne o panel (a) shows he p incipal join se s
iden i ied in he a ea. d) Example o an ambien seismic noise measu emen s a ion, showing he ield se up used o eco ding ambien
ib a ions o in e local si e esponse cha ac e is ics
122
A. SOKOLICEK, G. GRECHI, A. TANNER, L. bERGER, S. RIVELLINO, M. MONTAGNESE, G. M. MARMONI, Y. HUSSAIN & S. MARTINO
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
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Recei ed Feb ua y 2025 - Accep ed June 2025
