One Earthquake, Two Scenarios: The Baffling Case of the 1467 Siena Earthquake.

Historical seismology is a work in progress: the overall picture of a given historical earthquake, no matter how long taken for granted, can sometimes change, either thanks to the discovery of “new” (i.e. previously unknown or unheeded) historical sources, or by considering the research output of other disciplines. Historical seismologists tend to give precedence in their studies to written evidence, derived (when a choice is possible) from the sources 1) most likely to provide information useful to fulfill their main objectives (i.e. assessing macroseismic data points, reconstructing macroseismic fields and damage scenarios), and 2) not requiring long-drawn out, possibly unsuccessful searches that would hardly fit with their generally tight deadlines. Unavoidably, this approach mean to discard interesting but elusive evidence, whose records are buried too deep to make a search cost- effective, or were never written down at all but survive as the marks which past earthquakes left on buildings. It is up to the scholar to find ways and means to interpret these unwritten records, even if the readings taken are not always conclusive. The archaeoseismological study of historic towns and buildings allows to gain in-depth knowledge of how a given earthquake interacted with architectures and building components and in some cases, it can also provide evidence of the social, economic, or even political consequences of some earthquakes. The project PROTECT – Knowledge for PReventiON - Technique s for repairing seismic damage from the medieval period to the modern era (financed by the European Union’s Horizon 2020 research and innovation program together with a Marie Skłodowska-Curie Individual Fellowship) applies, on an entirely experimental basis, the methods of archaeoseismological analysis to the historic centre of Siena (Tuscany), to improve the knowledge of its context for purposes of seismic risk reduction. By weaving together the information gathered by different humanistic and scientific disciplines, the PROTECT ...