Ancient and Medieval Earthquakes in the Area of L’Aquila (Northwestern Abruzzo, Central Italy), A.D. 1–1500: A Critical Revision of the Historical and Archaeological Data

Abstract

This historical seismology study examines and supplements what is currently known from written sources and archaeological literature about the earthquakes that took place in the area of L’Aquila (central Italy), struck by a damaging earthquake on 6 April 2009 (Mw 6.3), from the ancient Roman period to the late Middle Ages (first through fifteenth century A.D.). The persistence and magnitude of earthquakes in this area has had a strong bearing on the economy and culture of the communities that resided there, a fact borne out by historical accounts. The goal of this revision is to prompt thinking about earthquakes missing from the hazard estimates as well as on return periods for destructive earthquakes in the area. It presents a critical collation of data previously scattered among historical catalogs and writings. Ten earthquakes are examined for their historical and cultural background with a view to highlighting the existence of written sources and explaining both the quality of the available data and the information shortfall. We also show the limits and uncertainty of the information available, coming as it does from tersely written texts giving patchy coverage. This state of knowledge is due either to sources being lost or in certain centuries not being produced (there is a millennium of “lost” earthquakes) and to the present state of historical and archaeological research in this field. The historical and archaeological data we present are often poor/hard to quantify. Yet they are known and hence pose the problem of how to improve the earthquake catalogs and devise new quantitative approaches to hazard estimation based on multi-disciplinary dialog.