After the publication of version 4.0 of the CPTI catalogue [Rovida et al., 2022], a work plan was launched for improving knowledge on a few hundreds earthquakes included in the catalogue after preliminary studies carried out in the last decade of the twentieth century and identified by the heading AMGNDT95. Here we present the results of the investigation carried out on three of these earthquakes (1897, 1916, 1972) and of a fourth one (1794) that was unknown to all earthquake catalogues, and whose study was started by our late colleague Giancarlo Monachesi who was unable to complete it in time. All the studied earthquakes are located in the Marches region, but each occurred in a different historical-cultural context. Considering them all together, provides some clues for a...