New study of the January-February 1703 seismic sequence in central Italy Introduction

This paper proposes a new study of the important seismic sequence that struck central Italy starting from January 1703. The sequence is currently quoted in the seismic catalogs with three main shocks that occurred between January 14th and February 2nd of that year, with magnitudes ranging between 6.0 and 6.9. Despite the already vast corpus of documentation and the extensive bibliography, due to the studies carried out between the 80s and 90s of the last century, the knowledge of this seismic sequence can be still improved. For this reason, an in-depth study was undertaken with a twofold objective: first to re-examine what was already known, starting from known sources, secondly to enrich the documentary resources to increase the number of intensity points, with new data. Information from approximately 390 locations was then analyzed, including more than 150 locations not included in the reference study of the sequence. The results of this new assessment are based on a chronological reconstruction hypothesis of the shocks of the sequence that, when assigning macroseismic intensity, considers the impact of damage progression due to multiple shocks. Through this approach, the shocks already quoted in the catalogs are reassessed as faithfully as possible, with a richer framework of knowledge than in the past. The intensity assessment (EMS-98) has allowed building a new and richer macroseismic dataset and proposing a new interpretation of the sequence, at the same time highlighting the problems that affect the uncertainty in the intensity.