Inhomogeneity of Macroseismic Intensities in Italy and Consequences for Macroseismic Magnitude Estimation

Abstract We show that macroseismic intensities assessed in Italy the last decade are not homogeneous with those of previous periods. This is partly related to recent adoption European Macroseismic Scale (EMS) place Mercalli–Cancani–Sieberg (MCS) scale used up about one ago. The underestimation EMS respect MCS a half degree on average and, even more significant, if estimated according approach developed for quick evaluations damage by seismologists Italian Department Civil Protection. also inhomogeneity over time differences between instrumental and magnitudes computed from intensity data, indicating an overestimation 0.3 units ones before year 1960 0.2 after such date. consistent studies hypothesized incorrect calibration mechanical recording seismometers operating surrounding countries introduction standard electromagnetic beginning 1960s. For reasons, preinstrumental earthquakes Catalogo Parametrico dei Terremoti Italiani seismic catalog, most hazard assessment Italy, might be overestimated, average, 0.1–0.2 magnitude units.