A Logical Methodology for Archaeoseismology: A Proof of Concept at the Archaeological Site of Sagalassos, Southwest Turkey

Archaeoseismology is currently controversial, with criticisms over the extent to which this research field can contribute to seismic-hazard analysis and, in- deed, as to whether man-made structures can be used as earthquake indicators at all. Addressing these concerns—in other words, refining the utility of archaeologi- cally derived earthquake information to permit its inclusion in earthquake-hazard assessments—requires first a systematic, quantitative, and interdisciplinary approach to the seismocultural record. Here, we modify a semiquantitative logic-tree formalism developed for palaeoseismology to explore a methodological scheme that can track uncertainties in successive stages of archaeoseismological investigation. The end result of our logic-tree formalism is a value that expresses the level of certainty to which an archaeological site has recorded a palaeoearthquake and thus reflects its relative significance with respect to a seismic-hazard analysis; we call this measure the archaeoseismic quality factor (AQF). We illustrate how the methodological scheme might work by applying it to Saga- lassos in southwest Turkey, an archaeological site for which earthquake effects are extensively reported. The resulting AQF that we derive from our critical review of the Sagalassos dataset is currently meaningless, because comparable values from equiva- lent reappraisals of earthquake evidence at other archaeological sites are needed for its relative significance to be appreciated. Nevertheless, the varying levels of uncertainty that we assign for different stages in the logic tree allow us to identify key weaknesses in the earthquake hypothesis at Sagalassos, deficiencies that might be redressed through future investigations onsite. The logic-tree formalism offers the potential of a standardized procedure to compile, categorize, and evaluate archaeoseismological information in a form that might, with refinement from wider earthquake archaeology studies, be appropriate for seismic-hazard analysis.