Historical Pathology And Past Interventions

The Monastery is situated in a Neocene tectonic graben between the mountains Egaleo and Korydallos at the west side of Athens, 150 m away from the E-W trending marginal fault between the alpine Mesozoic limestone and the post-alpine deposits (Mariolakos et al. 2000). Located in a tectonically active area, many intensive earthquakes damaged Dafni Monastery throughout the centuries (from 11th c. to our era). Partial collapses and extended damage were provoked to the structure and the mural mosaics, which led to major interventions. Detailed presentation of the long history of the monument is reported in Delinikolas et al. 2003, whereas a concise summary is given in this paragraph.

Two main phases of construction have been identified in the Katholikon of Dafni Monastery, both dating back to the middle Byzantine period. Although the construction type of masonry is similar in the two phases, the composition and final texture of pointing mortar used is different, thus allowing for the two phases to be identified in situ. The first phase comprises the main church and the narthex (Fig. 8). A reddish mortar containing crashed bricks was used for the pointing of the joints of the monument's external façades. At a second phase, a portico or exonarthex was added to the church (in its west part); masonry piers in the corners and marble ionic columns in the middle were used to support the arches of the added perimeter walls. Over the portico and the west part of the church a first floor was also added. Finally a spiral staircase tower was constructed in the NW corner of the narthex (Fig. 9). A whitish mortar with a yellowish patina was used for the pointing of the joints of the external façades.

Severe damage was provoked to the church during the 13th century, when Athens was occupied by the Franks. The first floor and the three groined vaults

Figure 9. West and south façade: 2nd construction phase, graphical representation of Stikas as modified by Delinikolas (Stikas 1962, Delinikolas et al. 2003).
Figure 10. Graphical representation of the W façade of the portico as restored by the Cistercians (Delinikolas et al. 2003).

of the exonarthex have probably collapsed, provoking severe damage to the rest of the structure. The narthex, the dome and its supporting system were as well severely damaged. Thus, extensive interventions were undertaken by the Cistercian monks mainly in the west part of the monument (13th-15th c.). The upper part of the west wall and the majority of arches, were reconstructed with curved stones following the gothic style (Figure 10). Furthermore the exonarthex was covered with a timber roof and bastions were built on the top ofthe walls. The remains ofthe constructions ofthe first floor, the narthex and the rest of the church were also locally repaired. These extended interventions in

Figure 11. West façade of the exonarthex before and after Stikas restoration interventions (photos Stikas, 1962).

the west part of the Katholikon can be considered as the third construction phase of the building.

During Othoman occupation strong earthquakes provoked further deterioration of the damages of the entire church. Cracks appeared on the vaulted roof of the crypt and the narthex, whereas severe damage and partial collapse occurred to the exonarthex and the spiral staircase. Thus, the arches of the exonarthex perimeter walls were filled with masonry, and extended alterations took place in the west part of the monument. During that period some of the ionic columns were taken by Lord Elgin to England.

The structural condition of the monument was further deteriorated during the 19th and the 20th centuries, due to numerous earthquakes occurred and major interventions were applied for the preservation of the monument. One should mention the 1889 and 1894 earthquakes (estimated magnitudes 6,7 and 7,0 on the Richter scale), the 1914 earthquake (M 6,0R), the 1981 earthquake (M 6,7R) and finally the 1999 one (M 5,9R). After the 1889 earthquake, the heavily damaged dome and its drum were removed and reconstructed. Three concentric iron rings (I-beams) were inserted at the base of the drum of the dome, as identified during the recent restoration works. Before removing the old dome, the mosaics were detached and, after their conservation, partially re-attached to the monument by Italian Conservators. During these interventions, the lime based mortar of the mosaics substrata was replaced with a hydraulic lime based one. The 1894 strong earthquake caused further damages; even the recently reconstructed dome and its drum were once again cracked. Extended interventions took place to the west part of the monument, including the reconstructions of almost the entire narthex (Troump, 1896). In the period of 1897 to 1907, two stone buttresses both sides of the north entrance to the church were constructed, while metallic trusses (fixed on new foundation) were installed both sides of the south central piers, together with iron plates and bars inserted at three levels, in order to confine them. In 1914, the suggestion is made for external confinement of the central cupola with an iron ring. This solution, however, was applied 40 years later.

In that period of 1955-1960 the ottoman interventions were removed from the exonarthex (Fig. 11)

Figure 12. Interventions to the monument: Plan.

and the Cistercian construction phase was restored by Stikas (Stikas 1962). The collapsed part was rebuilt and the missing ionic columns were replaced by masonry piers. A concrete beam was installed in the interior of the reconstructed parts, without affecting the byzantine remains of the SW pier. The upper part of the SE chapel was also reconstructed, while extended local re-pointing took place in various areas of the Katholikon, using mainly cement based mortars. Fortunately the non deteriorated old mortars were not removed. Thus, they survived to our days in better condition than those used by Stikas, which presented extended decay and during the recent restoration works were removed.

Figures 12 to 14, taken from Delinikolas et al. 2003, present the historical pathology and past interventions on drawings. The reconstructed parts of the monument are shown with solid colors. Yellow: 13th-15th c., orange: 1891, green: 1895, purple: 1897-1907, dark blue: 1955-60.

The 1981 earthquake (Alkyonides islands) caused numerous hair cracks to the building and severe damages to the mosaics. Thus, the pathology observed in the monument after the 1999 earthquake was only partly due to this severe earthquake.

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