A fuzzy logic methodology for assessing the resilience of past communities to tephra fall: a Laacher See eruption 13,000 year BP case

While volcanologists are experienced in assessing present and past volcanism, and while archaeologists are experts in understanding past societies, the study of how ancient volcanic activity has impacted contemporaneous communities remains little systematised. We here present a fuzzy logic-based methodology for bringing together expert assessments in evaluating the vulnerability and, by extension, the resilience of a group of late Pleistocene foragers to the Laacher See eruption, a large explosive eruption that affected continental Europe 13,000 years ago. Based on attributes assessing human health, shelter, food supply, and water supply our analyses suggest community resilience falls from 1.0 to 0.75 – 0.8 under a 5 cm tephra fall, to 0.45 – 0.50 with a 10 cm fall, and to 0.17 – 0.2 with an 18 – 20 cm tephra fall. Our explicit assessment of different experts’ evaluation of the different attribute’s relative importance facilitates a rigour in formulating such impact scenarios. The assessment methodology is rapid and can then be matched against existing evidence or, importantly, be used to also assess contemporary communities’ potential for loss under different tephra fall conditions. The methodology can be readily transferred between case studies and, in principle, between hazards, and could contribute significantly to the design of realistic disaster scenarios, which in turn serve to build resilience in at-risk communities.