The geoarchaeology of seismically triggered soft sediment deformation structures (SSDS)

Previous approaches to earthquakes in archaeology, characterizing the geoarchaeological subfield archaeoseismology, have focused on types of seismic destructions and anti-seismic constructions in architectural remains. A challenge often raised in archaeoseismology relates to issues of equifinality since other human or environmental factors can also cause the archaeoseismc types in question. Furthermore, geological markers of earthquakes are rarely identified directly, i.e., stratigraphically, with archaeoseismic evidence. To address these challenges, this paper offers a methodological innovation through the geoarchaeological subfield of soil micromorphology to investigate earthquakes in the form of seismically triggered soft sediment deformation structures (SSDS) in direct stratigraphic association with architecture. Applications to the case of Helike in Greece — infamous victim of a major earthquake in 373 BCE — reveal not only key evidence for three earthquake events in the form of seismically triggered SSDS but also other geological hazards, including flooding and rapid coastal change, in association with Hellenistic period (late fourth to second century BCE) architecture. The results offer advancements for archaeology and suggest that geoarchaeology and soil micromorphology applications become standard in archaeology, particularly archaeoseismology, for the identification and interpretation of earthquakes. These advancements offer new avenues for exploring geological aspects of the human past.