Seismicity of Western Crete and the destruction of the town of Kisamos at AD 365: Archaeological evidence

Abstract

The study of numerous archaeological excavations permits us to concludethat shortly after AD 355–361, the wealthy Roman town of Kisamos inwestern Crete was affected by a devastating earthquake (minimum intensityXI), which left many of the town's inhabitants buried under the ruins. Thisearthquake can be related to the July 21, 365 earthquake (M > 8),which was associated with a great tsunami, and was probably responsible forup to 9 m uplift of Western Crete; it probably resulted from thereactivation of a major thrust fault along the Hellenic Arc. Thearchaeological stratigraphy of Kisamos between circa AD 50 and AD650 testifies to two other, small-scale stratigraphic discontinuities that maybe related to two other smaller earthquakes, which produced 10–20 cmof coastal subsidence in AD 46–66 and in circa AD 270. There isevidence for a tsunami associated with the AD 46–66 earthquake, whichagrees with sedimentological data from the nearby ancient harbour ofPhalasarna, which was uplifted about 6.5 m in AD 365.The following evidence indicates that Western Crete is not seismicallyquiescent, as previously believed on the basis of historical data, but that ithas been affected by very strong, AD 365-type earthquakes followed byrelatively quiescence periods, that were at least several thousand years long:(1) Major earthquakes of Western Crete produced coastal uplift orsubsidence, while coastal stability indicates the absence of strongearthquakes; such stability characterizes this part of the island after AD365; (2) No evidence of earthquakes exist in the archaeological record ofKisamos between AD 365 and circa AD 650 and of Chania since AD1400/1500.