Palaeoseismological Information from Church Repairs Dated by Inscriptions: Evidence from Eighteenth Century Greece

Abstract Numerous inscriptions in churches in the Eastern Mediterranean commemorate the year of their repair, occasionally reflecting ignored postseismic recovery. To identify which inscription-dated repairs reflect seismic damage and then to derive palaeoseismological information, this study focuses on poorly known earthquakes with enough energy to damage clusters of nearby churches, usually structures with a dominant frequency >4–5 Hz, vulnerable to intensities VII at minimum. Clusters of church inscriptions, postdating known earthquakes and spread in areas compatible with typical seismic damage zones, are first identified. Then, background historical information is used to discard repairs reflecting insurgencies and wars, socioeconomic and political changes, or population changes. Remaining clusters of repairs can only represent postseismic recovery, and this result can be validated by architectural evidence. No other natural effect can account for such clusters in most parts of the Eastern Mediterranean. The information obtained can be transformed into minimum intensities and then into parametric seismic information. This method can also be applied to unrecorded seismic events. The advantages and limitations of the proposed method are discussed in three eighteenth century clusters of inscriptions in the territory of modern Greece, when church repairs were highly restricted under the Ottoman rule: (1) an earthquake ∼1700 in Kozani, with strong motion compatible to that of a 1995 Ms 6.6 earthquake; (2) an earthquake in Lamia in 1740, providing constraints on the activated fault; and (3) a wave of church construction in Samos Island, essentially reflecting population changes.