Geological and Historical‐Based Approaches to Define Scenario Earthquake: Case‐Studies and Application at Municipality‐Scale in Italy

This study compares two approaches for determining earthquake magnitude (M) and source‐to‐site distance (R) to assess seismic scenarios in Italy. The first method relies on geological criteria from the Italian seismogenic sources database (DISS3.3.0), while the second method uses historical earthquakes from the DBMI‐CPTI15 Italian catalogue. Both approaches lead to the identification of the M–R pairs (M ≥ 5.5) that can produce the most severe shaking on a site ( maximum scenario) or that affect the site most frequently ( modal scenario), in terms of median values of the spectral parameters obtained by an empirical ground motion model. The analysis encompasses around 8000 municipalities in Italy, suggesting a valuable approach for defining reference scenario earthquakes for damage and risk analyses, as well as for engineering design purposes.