faulting and effects of earthquakes on minoan archaeological sites in crete (greece)

www.elsevier.com/locate/tecto

Tectonophysics 382 (2004) 103–116

Faulting and effects of earthquakes on Minoan archaeological

sites in Crete (Greece)

C. Monaco*, L. Tortorici

Dipartimento di Scienze Geologiche and Centro di Archeologıa Cretese, Universita di Catania, Corso Italia 55, 95129 Catania, Italy

Received 13 December 2002; accepted 10 December 2003

Abstract

Examination of damages affecting the buildings of the archaeological sites of Phaistos and Agia Triada (southern Crete)

suggests that these Minoan settlements were probably destroyed by two major seismic events characterized by MKS intensities

of IX–X and occurred at the end of the Protopalatial (1700 BC) and the Neopalatial (1450 BC) periods. Geological and

morphological studies carried out in the neighbouring areas show the occurrence of E–W trending Quaternary normal fault

segments (Spili and Agia Galini faults) that control the present topography and morphology, and exhibit steep young scarps

mostly Holocene in age. These fault segments are related to a NW–SE extension direction, which is consistent with that

indicated by the available focal mechanisms of the earthquakes occurring in this area in the last 50 years. Combining structural

and seismic data we can infer that the Spili and Agia Galini fault segments could represent good candidates to be considered

active faults generating large earthquakes (Mi6.5) that were responsible for the damages of Phaistos and Agia Triada. This

hypothesis suggests that the Minoan palatial centres were destroyed by several large earthquakes related to ruptures along

distinct fault segments rather than by a single catastrophic event that caused the abrupt destruction of the Minoan civilisation in

the eastern Mediterranean.

D 2004 Elsevier B.V. All rights reserved.

Keywords: Archaeoseismology; Seismotectonics; Quaternary; Normal faulting; Seismicity; Crete; Aegean arc

1. Introduction characterized by epicentres located along a belt

The island of Crete is located on the apex of the

Hellenic arc (Fig. 1) and it is characterized by the

occurrence of both crustal and subcrustal earth-

quakes (McKenzie, 1978). Subcrustal earthquakes

(h>40 km) are related to the northeastward subduc-

tion of the African plate beneath the southern

Aegean Sea. The crustal seismicity (hV 40 km) is

0040-1951/$ - see front matter D 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.tecto.2003.12.006

* Corresponding author.

E-mail address: [email protected] (C. Monaco).

defined by instrumental earthquakes with Mz 5.5

(Papanastassiou et al., 2001; National Observatory

of Athens, 2002), which occurred since 1900 AD to

1992 (Table 1), extending from the Hellenic trench

to the northern part of the island (Fig. 1). Available

fault plane solutions (Pondrelli et al., 2002) for the

most recent earthquakes (Fig. 1) show that the

seismic events occurring in this area belong to three

major groups. The first group, located nearby the

Hellenic trench, is represented by contractional and/

or strike-slip events related to NNW shortening. The

second group, located between the Hellenic trench

Fig. 1. Seismotectonic map of Crete island showing historical crustal earthquakes with Mz 5.5 (triangles) as labelled in Table 1 (data from the

Earthquake catalogue of Greece of the National Observatory of Athens). Active faults are compiled as in Armijo et al. (1992) and Fassoulas

(2001). Available focal mechanisms (dots) are from Pondrelli et al. (2002); mechanism of 1965 event is from Lyon-Caen et al. (1987).

C. Monaco, L. Tortorici / Tectonophysics 382 (2004) 103–116104

and the southernmost part of the island, are indeed

represented by earthquakes characterized by T axes

oriented along a roughly NNE–SSW direction and

related to WNW–ESE trending normal faults. Fi-

nally, the third group, mostly occurring on land, is

characterized by focal mechanisms indicating a

dominant E–W-oriented T axes related to NNE–

SSW trending normal faults. In the Crete island, the

relations between earthquakes and tectonic structures

occurring both on land and off-shore are suggested

only for the group of seismic events characterized by

the E–W extension direction (Lyon-Caen et al., 1987;

Armijo et al., 1992; Fassoulas, 2001), whereas the 356

AD event with an estimated M>8 has been correlated

with thrusting processes along the Hellenic subduction

zone (Stiros, 2001).

The development of many settlements since the

Bronze age together with the occurrence of well

exposed Quaternary normal faults make the island

of Crete one of the most suitable area in the entire

Mediterranean to test the relations existing between

faulting and historical and proto-historical earthquake-

related effects. Our study has been carried out on the

southern part of the island along the plain of Messara

where are located several archaeological sites of the

Minoan civilization, like Phaistos and Agia Triada.

These sites were excavated since 1900 AD by the

Italian school of archaeology (Pernier, 1935; Pernier

and Bandi, 1951; Levi, 1976; La Rosa, 1985, 1992);

they exhibit well-preserved original features as no

excessive reconstruction were made. Moreover, these

sites are located close to E–W-oriented normal faults

that show evidence of Quaternary activity (Angelier,

1979).

In this study, we have first examined the differ-

ent typologies and geometry of damages occurring

in the archaeological sites of Phaistos and Agia

Triada. Secondly, a structural and geomorphic anal-

ysis has been carried out along the major Quater-

nary fault segments extending in the neighbouring

areas of the sites. Finally, we have correlated the

recent activity of fault segments with the possible

Table 1

Location of the instrumental earthquakes with Mz 5.5 which

occurred since 1900 AD to 1992 (data from the National

Observatory of Athens, 2002)

N Date Lat. Long. Depth

(H)

M

1 3/10/1923 34j.62 26j.53 12 5.5

2 24/3/1927 35j.45 26j.39 2 5.7

3 5/12/1938 35j.15 26j.24 23 5.8

4 16/6/1942 34j.40 26j.29 40 5.5

5 1/9/1942 35j.19 26j.73 22 6.0

6 4/5/1946 35j.29 23j.65 40 5.6

7 30/8/1947 35j.50 23j.37 34 6.2

8 22/5/1948 34j.65 24j.31 38 5.5

9 24/7/1948 34j.49 24j.49 20 6.4

10 17/12/1953 34j.47 24j.22 17 6.6

11 7/2/1953 34j.83 24j.11 33 5.7

12 14/5/1959 35j.11 24j.65 23 6.1

13 9/4/1965 35j.06 24j.31 39 5.9

14 27/4/1965 35j.65 23j.53 37 5.7

15 12/6/1969 34j.43 25j.04 ? 5.8

16 2/8/1969 34j.65 24j.01 ? 5.5

17 4/5/1972 35j.15 23j.56 14 5.9

18 29/11/1973 35j.18 23j.81 37 5.7

19 11/9/1977 35j.00 23j.10 – 5.9

20 21/6/1984 35j.31 23j.28 25 5.9

21 30/4/1992 35j.07 26j.63 20 5.6

22 30/4/1992 35j.22 26j.75 5 5.6

C. Monaco, L. Tortorici / Tectonop

destructive earthquakes responsible for damages in

the archaeological sites.

2. Damages on Phaistos and Agia Triada

The archaeological excavations of the Minoan

sites of Phaistos and Agia Triada show that the ruins

of these sites are affected by destructions compatible

with earthquakes and fire (La Rosa, 1995). Consid-

ering that these two sites developed in a time-span of

650 years, between 2000 and 1450 BC, a study of

the damages affecting the archaeological ruins can

provide useful information to obtain time-constraints

for possible natural events responsible for destruc-

tion. A detailed study has been thus carried out on

different typologies of damages of the two sites and

on their distribution. This study has been accompa-

nied by observations on the local geology to define

the possible relations between lithology and struc-

tures (fracture pattern) of the bedrock and building

damages.

2.1. Geological setting

The archaeological sites of Phaistos and Agia Triada

are located on the western part of the Plain of Messara,

an E–W-elongated Neogene–Quaternary basin that

separates the Psiloritis massif to the north from the

Asterousia ridge to the south (Fig. 1). This portion of

the island of Crete is a segment of the alpine orogenic

belt essentially formed by two major structural ele-

ments made up of several thrust sheets deriving from

the oceanic realm of the Neothetys and from the

Apulian continental margin (Bonneau, 1984; Hall et

al., 1984). The uppermost structural element includes

broken formations and melange terranes with ophio-

lites (Vatos and Arvi nappes) representing distinct

portions of an original accretionary wedge tectonically

overlain by crystalline rocks (Asteroussia nappe) be-

longing to the European paleomargin (Bonneau, 1984).

The lower structural element is made up of Mesozoic

carbonates of the Apulian paleomargin (Bonneau,

1984; Hall et al., 1984) which are represented by

distinct thrust sheets deriving from the deformation of

platform (Psiloritis and Tripolitza units) and pelagic

(Pindo and Ethia units) domains. During the Neogene,

the mountain building was accompanied (Hall et al.,

1984; Kilias et al., 1993; Fassoulas et al., 1994;

Fassoulas, 2001) by the development of a series of

syntectonic basins filled by coarse-grained continental

deposits (Tortonian Ambelouza Formation, Messinian

Varvara Formation and Lower Pliocene Courtes For-

mation). In the latest stages, Plio–Quaternary exten-

sional tectonics (Fassoulas, 2001) produced normal

fault systems which bound the major structural depres-

sions of the island, such as the Plain of Messara.

The palace of Phaistos and the center of Agia

Triada are located on an E–W trending hill made up

of sediments of the Messinian Varvara Formation

(Fig. 2). The bottom of this hill is formed by a 30-

m-thick sequence of whitish marls and silty clays

containing thin levels of marly limestones. These

sediments grade upward to a 10-m-thick interval

characterized by the occurrence of several beds of

yellowish calcarenites. At the top of the hill, well-

cemented calcarenites become dominant forming a

20-m-thick substratum on which the Phaistos palace

was built on.

The whole sequence is cut by two main sets of

fractures which have been clearly observed in the

hysics 382 (2004) 103–116 105

Fig. 2. Morphotectonic map of the Kedros mountain region and the northwestern sector of the Messara Plain (location in Fig. 1). In the inset,

lower hemisphere equal-area projection showing the attitude of the fault planes and associated slickensides collected along the Spili fault is

reported; large arrows indicate the mean extension direction obtained by inversion of slickensides data.


upper calcarenitic interval (Fig. 3a). The first set is

mainly oriented N45jE and is characterized by a

spacing ranging 60–100 cm. The second set has

N130jE direction with a spacing of 40–70 cm.

These two sets enclose sub-rectangular blocks, which

favoured the quarrying of the rocks by the Minoan

people, as observed in the ancient quarry located at

the southernmost edge of the site of Phaistos.

From the morphological point of view, the slopes

of the hill exhibit several landslides because of the

clay nature of the sequence that forms its backbone.

The continuous retreat of landslide-scarps joining the

cliff of the top of the Messinian sequence has caused

the occurrence of large rock-falls affecting the calcar-

enitic interval. The most impressive rock-fall occur-

ring in the area affects the SE corner of the central

court of the palace of Phaistos, which was partially

destroyed (Fig. 4).

2.2. Phaistos

Phaistos is the best preserved archaeological site

of the Minoan civilisation. In this site two super-

imposed palaces related to the Protopalacial period

(2000–1700 BC) and to the Neopalacial period

(1700–1450 BC) are well preserved (Pernier, 1935;

Pernier and Bandi, 1951; Levi, 1976; La Rosa, 1985,

1989, 1992). The older building (first palace) is

Fig. 3. Pole-density diagrams showing the orientation of joints

affecting the substratum (diagram a) and the stone walls of the first

Palace of Phaistos (diagram b) and of the Royal villa of Agia Triada

(diagram c).

C. Monaco, L. Tortorici / Tectonophysics 382 (2004) 103–116 107

affected by huge destructions, attributed to earth-

quakes and fire that have been sealed by the con-

struction of the foundations and walls of the second

palace. This implies that the detailed study on the

nature and distribution of the damages affecting the

first palace can provide useful age-constraints on the

natural event responsible for the destruction of the

older palace.

The ruins of the older palace (Fig. 4), well

exposed at the SW corner of the site, consist of

20 rooms, mainly used for storage, with walls that

reach 6 m in height. The architecture of the building

is characterized by three distinct paved levels con-

taining pottery indicating an age ranging between

the 1850 and 1700 BC. Archaeological studies

testify that the older palace was partially recon-

structed with the addition of a ramp, the re-building

of the third level and with the arrangement of the

atrium (Levi, 1976; La Rosa, 1995). The whole

quarter was finally levelled and filled with a con-

crete, locally named astraki, to form the foundations

of the second palace.

The damages affecting the older buildings are

mainly represented by tilting of walls that are also

affected by a widespread fracturing and by falls of the

floors. The walls are usually tilted and rotated along

horizontal axes oriented both along the E–W and the

N–S directions, with rotating angles ranging between

7j and 25j (Fig. 4). The dividing-wall between the

rooms LVIII and LIX is tilted southwards at 7j,whereas the buttress between the rooms LIX and

LX reaches values of 15j (Fig. 4). Northwards and

southwards tilting and rotations with angles ranging

from 5j and 7j affect both the stairs and the northern

wall of the atrium. The major tilting are indeed

observed on the walls oriented N–S, which usually

lean to the west. In particular the western wall of the

room LXII is tilted to the west at 8j, whereas the

dividing-wall between the rooms LIII and LVI reaches

values of 20j describing as a whole an arc-shaped

geometry. Values of 20j are also measured on the wall

that, located at the third paved level, separates the

room LIII from the room LV. The western wall of the

atrium LVI leans forward at 25j towards the court

LXX with its barycentre out from the vertical projec-

tion of the horizontal rotation axis (Fig. 5). The

consequent collapse of the wall was inhibited by the

occurrence of a large buttress constituted by a pile of

Fig. 4. Plan of the southwestern part of the Phaistos Minoan palace (for location, see the inset). The remnants of the first palace (2000–1700

BC) are in white, whereas the foundations of the second palace (1700–1450 BC) are in grey. Roman numbers refer to the distinct rooms of the

first palace; arrows indicate the polarity of the tilting suffered by the walls.


ruins (Fig. 5). This is made up of blocks of stones and

fragments of walls belonging to the higher levels of

the palace with a ruditic and arenitic matrix cemented

by carbonate concretions. One of the most impressive

damages of the older palace is represented by the

collapse of the floor of the second level of the room

Fig. 5. View from the north of the western wall of the atrium LVI of the Phaistos Minoan palace tilted of 25j to the west towards the court LXX.Note the buttress constituted by a pile of ruins (a), which supports the stone wall whose barycentre is out from the vertical projection of the

horizontal rotation axis (for location, see Fig. 4).


LV, which was also accompanied by a southward

rotation at 15j (Fig. 6). To the south, on the western

wall of the room LV, a horizontal wooden beam slot

running at the same level of the un-collapsed portion

of the second floor is well preserved (Fig. 6). This

suggests that the collapsed second floor was recon-

structed after his destruction. Finally, the walls are

also affected by fractures distributed in two distinct

sets oriented along N120jE and N45jE directions

(Fig. 3b). This fracture pattern is consistent with the

joint distribution observed on the substratum.

The characters and distribution of the damages,

compared with that observed in other historic town

centres located in Italy, Bulgaria, Greece and Turkey

(Christoskov et al., 1995; Di Vita, 1995; Gergova et

al., 1995; Giuffre, 1995; Stiros, 1996, 2000; De Boer

and Hale, 2000; Waelkens et al., 2000) strongly

suggest that they could be related to a seismic event

characterized by local MKS intensity I = IX–X and

occurred nearby (at about 10–20 km) the site. The

relations between the construction of the first and the

second palace suggest that this earthquake occurred at

the end of the Protopalacial period (La Rosa, 1995)

causing the disruption of the older palace by shaking

strongly conditioned by the fracture system affecting

the rocks of the substratum.

2.3. Agia Triada

The Royal Villa of Agia Triada (Fig. 7), situated 3

km NW of Phaistos (Fig. 2), shows an overall L-

shaped plan and it is related to the Neopalacial period

(beginning of the XVII century BC). The palace (La

Rosa, 1985, 1989, 1992) extends for a length of about

80 m along the E–W direction and for about 50 m

along the N–S direction and it is constituted by 30

rooms separated by walls that reach 3 m in height. The

occurrence of several stairs suggests that the palace

was constituted by at least two distinct levels. The

restoration of the ruins also preserved the original

damages caused by the final disruption of the palace

occurred in the 1450 BC.

The most impressive damages that affect the

ruins of Agia Triada are located in the official

apartments of the western portion of the palace. In

the northwest wing the main-walls are tilted west-

wards at angles ranging between 5j and 8j, where-as in the northeast wing they are inclined to the

north reaching angles of 10j (a in Fig. 7, and Fig.

8). At places, blocks of the outside main walls are

rotated along vertical axes with angles ranging from

5j to 10j. The stairs of the northeast wing (b in

Fig. 7) are strongly ruined with the steps tilted

Fig. 6. West-looking of the collapsed floor of the second level of the room LVof the Phaistos Minoan palace. Note the well-preserved horizontal

wooden beam slot (see arrow) running at the same level of the un-collapsed portion of the second floor (for location, see Fig. 4).


towards the west of about 10j. The walls are also

affected by pervasive fractures, distributed in two

main sets oriented N65jE and N115jE (Fig. 3c),

which are consistent with the distribution of joints

in the substratum and in the ruins of the older

palace of Phaistos.

Also in this site, the damage scenario is character-

istic of a local intensity I = IX–X on the MKS macro-

seismic scale. This earthquake occurred nearby the

archaeological site in the 1450 BC and probably

caused also the disruption of the second palace of

Phaistos and of other minor sites of the plain of

Messara such as the rural village of Kannia (Fig. 1)

near Gortina (La Rosa, 1985).

3. Late Quaternary normal faulting

The features of damages occurring at Phaistos and

Agia Triada suggest that they could have been

caused by seismic events which could be related to

ruptures along the Late Quaternary faults occurring

on the island of Crete (Angelier, 1979; Armijo et al.,

1992; Fassoulas, 2001). Despite the high level of

Fig. 7. Plan of the Royal villa of Agia Triada with the observed damages on the stone walls (a) and stairs (b).


crustal seismicity (Table 1) and the occurrence of

active faults characterizing the island of Crete, de-

tailed relationships between faulting and earthquakes

have not been clearly documented. In the geological

approach, we thus focus on potential active faults

occurring nearby the archaeological sites of Phaistos

and Agia Triada. These sites are located at the

western edge of the Plain of Messara, along the

southern border of the Psiloritis mountain range that

occupies the central part of the island of Crete (Fig.

Fig. 8. View from the south of the westward tilted stone wall of a magazine belonging to the north–west wing of the villa of Agia Triada (for

location, see Fig. 7).


2). The southern front of this massif is bounded by

south-dipping Quaternary normal faults that extend

in ESE direction for total length of about 70 km.

About 20 km NW of the archaeological sites (Fig. 2),

a normal fault segment exhibits a young morpholo-

gy, mostly Late Pleistocene–Holocene, indicating a

very recent activity. This segment, known as Spili

fault (Angelier, 1979), bounds to the south the

Kedros ridge, a massif constituted by the Triassic–

Paleogene carbonate sequence of the Ethia unit (Fig.

2). Southwards, the Spili fault bounds the Akoumia-

nos river valley, a tectonic depression filled by

Quaternary conglomerates and sands unconformably

covering the Tortonian deposits of the Ambelouza

Formation (Fig. 2). The fault trace extends at the

boundary of the mountain front for a total length of

about 25 km. It strikes along a direction ranging

between N100jE and N140jE and dips at 60–70j to

the south. Two superimposed generations of slicken-

sides are well recognizable on the fault plane. The

older generation, visible only in places, shows

pitches ranging between 50j and 65j, whereas the

younger generation of slicknesides, which pervasive-

ly affect the fault plane, has pitches between 90j and


110j. Inversion of the youngest slickensides data

yield a roughly NE extension direction (see inset a in

Fig. 2).

The cumulative height of the Spili fault scarp varies

along strike and reaches values of 300 m at its

northwestern edge. Between the villages of Kria Brisi

and Spili (Fig. 2), a 8–10-m high rejuvenated scarp is

well exposed at the base of the cumulative degraded

escarpment. In this sector, the footwall is entrenched

by narrow V-shaped canyons and wine glass valleys.

On the hangingwall that is characterized by the occur-

rence of an unentrenched drainage network, syntec-

tonic sedimentary wedges occur. They are constituted

by alluvial and colluvial deposits made up of calcar-

eous breccias and conglomerates deriving from the

unroofing of the uplifting footwall. The thickness of

these sediments strongly decreases from the hanging-

wall to the footwall, where they are represented by a

few metres thick indurated breccias directly lying on

the calcareous bedrock. Deposits with similar features

Fig. 9. View of the Spili fault escarpment (for location, see Fig. 2). Note

endured Wurmian deposits.

have been observed along other active fault in Pelo-

ponnesus such as the Sparta and Kalamata faults

(Armijo et al., 1991, 1992). These deposits have been

related to cold and dry climate occurring during the

Wurmian glaciation (Dufaure, 1977), which gave rise

to uniform steep slopes (z 30j) at the base of Qua-

ternary fault escarpment. Thus they constitute a good

marker to evaluate the fault activity since 10–11 ka,

when the glacial conditions ceased and the slip rate

outpaced erosion and sedimentation rates (Armijo et

al., 1992; Benedetti et al., 2002). The 8–10-m high

scarp at the base of the mountain front has been

interpreted as the result of the Holocene activity along

the Spili fault. In fact, as along the Sparta and Kala-

mata faults, this scarp offsets the calcareous slope near

the mountain-piedmont junction, where the alluvial

and colluvial deposits are severely deformed showing

in place roll-over anticlines and mountain-wards tilting

with angles that reach values of 30j. This young scarpmay be interpreted as resulting from several faulting

the 1.5-m high scarplet located at the mid-slope which offsets the


events consequent to crustal earthquakes as observed

along other active faults in Afar, Greece and Italy

(Tapponnier et al., 1990; Armijo et al., 1991, 1992;

Stewart and Hancock, 1991; Piccardi et al., 1999;

Benedetti et al., 2002). On this basis, a rough vertical

slip-rate of about 0.7 mm/year can be estimated for the

Spili fault during the last 10 ka. Between Spili and Kria

Brisi (Fig. 9), the Holocene scarp is also characterized

by the occurrence of a 12-km long and 1–1.5-m high

light-coloured basal ribbon which could be related to

the last seismic event.

Along the northern border of the Plain of Messara

(Fig. 2), the E–W trending Agia Galini fault charac-

terized by a very young morphology occurs. To the

west, this fault extends offshore along the coastline

between Agia Pavlos and Agia Galini defining on the

footwall a coastal cliff with a maximum height of 400

m. Onshore, to the East of Agia Galini, this fault

segment is defined by a 100-m high cumulative scarp,

characterized by the occurrence of a series of trape-

zoidal and triangular facets. The Agia Galini fault

separates the Tortonian clastic deposits cropping out

on the footwall from the Quaternary alluvial deposit

of the Plain of Messara on the hangingwall (Fig. 2).

On the footwall, two main marine terraces occurring

at a maximum elevation of 163 m and 223 m are

recognizable, testifying for a sustained uplift of the

upthrown block.

4. Conclusions

The analysis of damages affecting the archaeolog-

ical sites of Phaistos and Agia Triada reveals that

these settlements were probably destroyed by two

large seismic events with IX–X MKS intensity oc-

curred around 1700 and 1450 BC, respectively. More-

over, geological and morphological studies carried out

in the neighbouring areas show the occurrence of E–

W trending Quaternary fault segments belonging to a

50-km long system that control the present topogra-

phy and exhibit steep young scarps with very sharp

morphology, mostly Holocene in age. These normal

faults are activated by a NW–SE-oriented extension

which is consistent with the seismicity (see focal

mechanisms in Fig. 1) characterizing this area in the

last 50 years. On this basis, we may infer that the Spili

and Agia Galini faults are good candidates to be

considered active faults generating large earthquakes

that could have destroyed the settlements of Phaistos

and Agia Triada.

The empirical relations of magnitude versus surface

rupture length (SRL) and magnitude versus maximum

vertical displacement (MVD) compiled for historical

and instrumental earthquakes from the broader Aegean

region (Pavlides and Caputo, 2004) represent a good

tool to estimate the magnitude of a possible earthquake

related to ruptures occurring along the Spili fault. This

fault segment, which extends for a total length of about

25 km, is characterized by a 8–10-m high Holocene

escarpment and by a 12-km long and 1.5-m high

scarplet. Assuming that the up to 1.5-m high scarplet

has been generated by a single seismic event and that

the rupture at the surface corresponds to a length of 12

km, both the relations M versus SRL and M versus

MVD suggest that the Spili fault could generate earth-

quakes with Mi6.5. These estimated values of mag-

nitude and surface rupture are also consistent with the

empirical relationships among magnitude, rupture

length and surface displacement obtained for the active

normal faults all over the world (Wells and Copper-

smith, 1994). Taking into account that the 8–10-m

high Holocene scarp of the Spili fault could be

considered as the result of the summation of 5–7

earthquakes with Mi6.5, for this fault segment a

recurrence interval of 1.4–2.0 ka for the last 10 ka

could be inferred. The Spili fault extending NNW of

the sites of Agia Triada and Phaistos may thus be

considered as potential source of seismic events that,

characterized by Mi6.5, were responsible for the

damages in these Minoan settlements. Nevertheless,

the recurrence interval estimated for this structure is

not compatible with the lapse of time of about 250

years occurring between the two inferred earthquakes

that destroyed Phaistos (1700 BC) and Agia Triada

(1450 BC). Two distinct hypotheses can be inferred to

explain this irregularity of earthquake time intervals.

The first hypothesis assumes that the two events were

generated by ruptures occurring along two distinct

faults (e.g. the Spili and the Agia Galini faults)

belonging to the same seismogenic zone. Different

ruptures along adjacent fault segments could be

explained with changes of the Coulomb failure stress

caused by earthquake ruptures occurring along a fault,

triggering the subsequent shock on the other one (King

et al., 1994; Jacques et al., 1996, 2001). Following this


line of reasoning, we suggest that when a rupture

occurred along the Spili fault, this perturbed the stress

state of the adjacent segments (e.g. the Agia Galini

fault) favouring subsequent ruptures. The second hy-

pothesis supposes that the Spili fault is characterized

by the occurrence of non-periodic earthquakes. This

assumption is suggested by cosmogenic dating

obtained on the Sparta normal fault scarp which show

time intervals ranging between 500 and 4500 years

(Benedetti et al., 2002).

Finally, both of the hypotheses imply that the

Minoan palatial centres were destroyed by large

earthquakes related to ruptures along distinct faults

affecting the Crete island rather than a single cata-

strophic event that caused the abrupt destruction of

the Minoan civilisation in the eastern Mediterranean

(see Driessen and Macdonald, 2000 and reference

therein).

Acknowledgements

We wish to thank Vincenzo La Rosa, Head of the

Centro di Archeologia Cretese of the University of

Catania, for access to the Minoan sites of Phaistos and

Agia Triada and for thoughtful discussions and for

providing the archaeological data reported in this

paper.

References

Angelier, J., 1979. Neotectonique de l’Arc egeen. Soc. Geol. Du

Nord 3 (418 pp.).

Armijo, R., Lyon-Caen, H., Papanastassiou, D., 1991. A possibile

normal fault rupture for the 464 BC Sparta earthquake. Nature

351, 137–139.

Armijo, R., Lyon-Caen, H., Papanastassiou, D., 1992. E–W exten-

sion and Holocene normal fault scarps in the Hellenic arc. Ge-

ology 20, 491–494.

Benedetti, L., Finkel, R., Papanastassiou, D., King, G., Armino, R.,

Ryerson, F., Farber, D., Flerit, F., 2002. Post-glacial slip history

of the Sparta fault (Greece) determined by 36Cl cosmogenic

dating: evidence for a non-periodic earthquakes. Geophys.

Res. Lett. 29 (87), 1–4.

Bonneau, M., 1984. Correlation of the Hellenides nappes in the

south-east Aegean and their tectonic reconstruction. In: Dixon,

J.E., Robertson, A.H.F. (Eds.), The Geological Evolution of the

Eastern Mediterranean. Geol. Soc. London, Spec. Publ., 17,

pp. 517–528.

Christoskov, L., Gergova, D., Iliev, I., Rizzo, V., 1995. Traces of

seismic effects on archaeological sites in Bulgaria. Ann. Geofis.

38, 907–918.

De Boer, J.Z., Hale, J.R., 2000. The geological origins of the oracle

at Delphi, Greece. In: McGuire, W.G., Griffiths, D.R., Hancock,

P.L., Stewart, I.S. (Eds.), The Archaeology of Geological Cata-

strophes. Geol. Soc. London, Spec. Publ., 171, pp. 399–412.

Di Vita, A., 1995. Archaeologists and earthquakes: the case of 365

A.D. Ann. Geofis. 38, 971–976.

Driessen, J., Macdonald, C.F., 2000. The eruption of the Santorini

volcano and its effects on Minoan Crete. In: McGuire, W.G.,

Griffiths, D.R., Hancock, P.L., Stewart, I.S. (Eds.), The Archaeo-

logy of Geological Catastrophes. Geol. Soc. London, Spec.

Publ., 171, pp. 81–93.

Dufaure, J.J., 1977. Neotectonique et morphogenese dans une

peninsula mediterraneenne: Le Peloponnese. Rev. Geogr. Phys.

Geol. Dyn. 19, 27–58.

Fassoulas, C., 2001. The tectonic development of a Neogene basin

at the leading edge of the active European margin: the Heraklion

basin, Crete, Greece. J. Geodyn. 31, 49–70.

Fassoulas, C., Kilias, A., Mountrakis, D., 1994. Post-nappe stack-

ing extension and exhumation of HP/LT rocks in the island of

Crete, Greece. Tectonics 13, 127–138.

Gergova, D., Iliev, I., Rizzo, V., 1995. Evidence of a seismic event

on Thracian tombs dated to Hellenistic period (Sveshtari, north-

eastern Bulgaria). Ann. Geofis. 38, 919–926.

Giuffre, A., 1995. Seismic damage in historic town centres and

attenuation criteria. Ann. Geofis. 38, 837–843.

Hall, R., Audley-Charles, M.G., Carter, D.J., 1984. The signifi-

cance of Crete for the evolution of the eastern Mediterranean.

In: Dixon, J.E., Robertson, A.H.F. (Eds.), The Geological Evo-

lution of the Eastern Mediterranean. Geol. Soc. London, Spec.

Publ., 17, pp. 499–516.

Jacques, E., King, G.C.P., Tapponnier, P., Ruegg, J.C., Manighetti,

I., 1996. Seismic activity triggered by stress changes after the

1978 events in the Asal Rift, Djibuti. Geophys. Res. Lett. 23,

2481–2484.

Jacques, E., Monaco, C., Tapponnier, P., Tortorici, L., Winter, T.,

2001. Faulting and earthquake triggering during the 1783 Cala-

bria seismic sequence. Geophys. J. Int. 147, 499–516.

Kilias, A., Fassoulas, C., Mountrakis, D., 1993. Tertiary extension

of continental crust and uplift of the Psiloritis metamorphic core

complex at the central part of the Hellenic arc. Bull. Geol. Soc.

Greece 28, 297–314.

King, G.C.P., Stein, R.S., Lin, J., 1994. Static stress changes and the

triggering of earthquakes. Bull. Seism. Soc. Am. 84, 935–953.

La Rosa, V., 1985. Preliminary considerations on the problem of the

relationship between Phaistos and Haghia Triada. Scripta Med-

iterranea 6, 45–54.

La Rosa, V., 1989. Nouvelle donnees du Bronze moyen au Bronze

recent a Hagia Triada. Aegeum 3, 81–92.

La Rosa, V., 1992. Ayia Triada and Phaistos. In: Myers, J.W.,

Myers, E.E., Cadogan, G. (Eds.), The Aerial Atlas of Ancient

Crete. Univ. of California Press, Berkeley, pp. 70–77.

La Rosa, V., 1995. A hypothesis on earthquakes and political power

in Minoan Crete. Ann. Geofis. 38, 881–891.

Levi, D., 1976. Festos e la civilta minoica. Ateneo, Roma, p. 864.

Lyon-Caen, H., Armijo, R., Drakopoulos, J., Baskoutass, J., Deli-


bassis, N., Gaulon, R., Kouskouna, V., Latoussakis, J., Makro-

poulos, K., Papadimitriou, P., Papanastassiou, D., Pedotti, G.,

1987. The 1986 Kalamata (South Peloponnesus) earthquake:

detailed study of a normal fault, evidences for east–west exten-

sion in the Hellenic arc. J. Geophys. Res. 93, 14967–15000.

McKenzie, D., 1978. Active tectonics of the Mediterranean region.

Geophys. J. R. Astron. Soc. 30, 109–185.

National Observatory of Athens, 2002. Earthquake Catalogue of

Greece. Web site http://www.gein.noa.gr.

Papanastassiou, D., Lataoussakis, J., Stavrakakis, G., 2001. A re-

vised catalogue of earthquakes in the broader area of Greece for

the period 1950–2000. Bull. Soc. Geol. Greece 34, 1563–1566.

Pavlides, S., Caputo, R., 2004. Magnitude versus faults’ surface

parameters: quantitative relationships from the Aegean Region.

Tectonophysics 380, 159–188.

Pernier, L., 1935. Il palazzo minoico di Festos. La Libreria dello

Stato, Roma, p. 786.

Pernier, L., Bandi, L., 1951. Il palazzo minoico di Festos. La Libre-

ria dello Stato, Roma, p. 647.

Piccardi, L., Gaudemer, Y., Tapponnier, P., Boccaletti, M., 1999.

Active oblique extension in the central Apennines (Italy):

evidence from the Fucino basin. Geophys. J. Int. 139,

499–530.

Pondrelli, S., Morelli, A., Ekstrom, G., Mazza, S., Boschi, E.,

Dziewonski, A.M., 2002. European–Mediterranean regional

centroid-moment tensors: 1997–2000. Phys. Earth Planet. Inter.

130, 71–101.

Stewart, I., Hancock, P.L., 1991. Scales of structural heterogeneity

within neotectonic normal fault zones in the Aegean region.

J. Struct. Geol. 13, 191–204.

Stiros, S.C., 1996. Identification of earthquakes from archaeological

data: methodology, criteria and limitations. In: Stiros, S., Jones,

R.E. (Eds.), Archaeoseismology. British School at Athens, Fitch

Laboratory Occasional Paper, vol. 7, pp. 129–152.

Stiros, S.C., 2000. Fault pattern of Nisyros Island volcano (Aegean

Sea, Greece): structural, coastal and archaeological evidences.

In: McGuire, W.G., Griffiths, D.R., Hancock, P.L., Stewart, I.S.

(Eds.), The Archaeology of Geological Catastrophes. Geol. Soc.

London, Spec. Publ., 171, pp. 385–398.

Stiros, S.C., 2001. The AD 365 Crete earthquake and possible

seismic clustering during the fourth to sixth centuries AD in

the eastern Mediterranean: a review of historical and archaeo-

logical data. J. Struct. Geol. 23, 545–562.

Tapponnier, P., Armijo, R., Manighetti, I., Courtillot, V., 1990.

Bookshelf faulting and horizontal block rotations between over-

lapping rifts in southern Afar. Geophys. Res. Lett. 17, 1–4.

Waelkens, M., Sintubin, M., Muchez, P., Paulissen, E., 2000. Ar-

chaeological, geomorphological and geological evidence for a

major earthquake at Sagalassos (SW Turkey) around the middle

of the seventh century AD. In: McGuire, W.G., Griffiths, D.R.,

Hancock, P.L., Stewart, I.S. (Eds.), The Archaeology of Geo-

logical Catastrophes. Geol. Soc. London, Spec. Publ., 171,

pp. 373–384.

Wells, D.L., Coppersmith, J.K., 1994. New empirical relationship

among magnitude, rupture length, rupture width, rupture area

and surface displacement. Bull. Seism. Soc. Am. 84, 974–1002.

http:\\www.gein.noa.gr

faulting and effects of earthquakes on minoan archaeological sites in crete (greece)

Documents