Magnitude and epicentral uncertainty of historical earthquakes in northeastern Italy from macroseismic data

Historical earthquakes are essential for long-term seismicity and seismic-hazard assessment, but their location and magnitude are often poorly constrained by sparse and uneven intensity data. We apply the Bakun and Wentworth grid-search method to selected Intensity Data Points (IDPs) from DBMI15 for four earthquakes in northeastern Italy, using Mw-calibrated Italian attenuation models. We estimate intensity centres, intensity-based Mw values, and empirical 67% and 95% confidence contours. The resulting maps make the spatial resolution of each macroseismic field explicit and provide a quantitative layer for comparison with CPTI15/Boxer solutions and DISS seismogenic sources.