Stathis C. Stiros

Alexandria in Egypt is reported to have been highly affected in A.D. 320 by an earthquake somewhat similar to the 1955 M 6.4 event, the strongest near-field event in this country since 1900. The A.D. 320 event was later characterized as spurious, reflecting a misunderstanding of a word referring to the impacts of the heresy of Arius on the Alexandria Church by the ninth century historian Theophanes. Shedding light on this earthquake is important because it is included in earthquake catalogs and studies of seismic risk; the latter is high due to the type of structures and foundation soils of Alexandria, a sprawling city of nearly six million people. An analysis of the previously examined and ignored ancient texts, of their sources, of their historical context, as well as of their copying, editorial, and translation history, indicates no earthquake in Alexandria in A.D. 320, nor that this spurious event reflects the misunderstanding of an ancient word. A possibility is that the information on an earthquake in the year A.D. 320, confirmed by another sixth century book, refers not to Alexandria, but to another town, the composite name of which was corrupted. According to this hypothesis, the A.D. 320 earthquake affected Alexandria Troas, on the Aegean coast, near the Homeric Troy, and close to a strand of the North Anatolian fault and the Aegean Sea, or Alexandria Catisson (Alexandria ad Issum), modern Iskenderun, near the East Anatolian fault. Both towns are in highly seismically active areas in Türkiye (Turkey).

Philippi, a small Greek and then Roman town in Northern Greece, became a flourishing pilgrimage center in the fourth century, commemorating the first Christian community in Europe established by St. Paul. After the sixth century, impressive churches and other buildings of the town were turned into ruins, currently registered in the UNESCO World Heritage. The reasons and timing of the demise of the town are unclear, and several scenarios have been proposed to explain them. Analysis of excavation data indicates no signs of invasion by Slavs or Avars, but sitewide destruction, which can be assigned to a major unrecorded earthquake that occurred probably within approximately 15 yr after 615, as numismatic data (hiatus in coin circulation) reveal. This result is important because Philippi is in a low-seismicity region, whereas an earthquake alone cannot easily explain the demise of a town with a millennium-long history. However, it was found that the destructive earthquake had produced an up to 10 m drop in a karstic spring feeding a low-gradient aqueduct, depriving Philippi of a main infrastructure of a Roman and Byzantine town, especially of a pilgrimage center. This, in combination with the overall sociopolitical situation, hindered the town’s postseismic recovery. The destruction pattern and extent, as well as the structural characteristics of the destroyed buildings, testify to a strong earthquake of intensity IX or X (MMS) from a nearby source. Two nearby known active normal faults are candidates for the earthquake source, but the Xanthi fault, well marked in the topography, and especially its continuation offshore, is more likely, because it runs mid-distance (about 20 km) from Philippi and the Town of Thasos, another site for which seismic damage at the same period was claimed.

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.

In January 2004 a Mediterranean cyclone in the Aegean Sea seriously affected the north coast of Samos Island, damaged the harbour mole of a coastal village, and catapulted its building material along with heavy boulders to the inner harbour basin. This area was also affected by a 2020, magnitude 7.0 earthquake which produced localized tsunamis. The evidence from the 2004 cyclone, with boulders shifted from known positions and with known trajectories, can contribute to the debate for the causes of mobilization of coastal boulders because of storms, tsunamis, or their combination.

“De Mundo” (“On the Cosmos”), an influential ancient anonymous treatise (manuscript) covering natural phenomena and philosophical ideas, is assigned by the majority of investigators to pseudo‐Aristotle, an unknown philosopher of Roman times mimicking Aristotle. This article focuses on differences in the geological content between “Meteorologica” (“Meteorology”), the famous work of Aristotle on Natural Sciences, and “de Mundo.” Four themes are examined: the evolution of the legend of the 373 BC earthquake and tsunami at Helike and Boura (Gulf of Corinth, Greece) based on new geoarchaeological and archaeological evidence, volcanic eruptions of the Aeolian Islands and Etna, but not of Vesuvius (Italy), neurotoxic effects of gas seepage, mostly in oracles, and the style of referencing to geological information. The new geoarchaeological evidence permits the dating of “de Mundo” in the first century AD, thereby refining previous interpretations, and implies no evidence of change in Aristotle's philosophical and geographical ideas at the end of his life. The overall analysis provides an explanation for the legend of the catastrophe of Helike, and it highlights the potential of geoarchaeological methods to provide new insights even into literary, philosophical, and geographical issues, and the dating of various ancient manuscripts.

Understanding the length and subdivisions of ancient length units is necessary for Archaeology, Architecture, and engineering, among other fields. These metrological units derive from anthropocentric concepts (fathom, cubit, foot, finger, etc.) and hence their metrological characteristics are variable and unknown for various ancient civilizations. The Roman length units are well determined, but the ancient Greek units are not. A rule sculpted in a metrological relief recently permitted the recognition of the Doric foot as having a length of 327 mm, but the broader use and divisions of this length unit remain unknown. In this article we present evidence of use of the Doric foot from the modeling of an ancient, atypical small theatre of the 4th–3rd century B.C., at Makyneia, on the western Greece mainland. It was found that this structure was designed using the Doric foot and its division in 24 (or even 12) digits. This result from a small provincial town indicates that the Doric foot was in broad use in architectural and engineering works of the ancient Greek World, and this result may be used to solve various problems of that era.