Recent earthquakes (2000-2021) in and around the Friuli Venezia Giulia region (NE Italy) and quality improvements of the OGS network monitoring capabilities

Regular monitoring of the seismicity in north-eastern Italy began in 1977, one year after the strong earthquake that caused about 1000 victims in Friuli. Over the years, the monitoring network operated by OGS has increased, today reaching a consolidated level in terms of geometry and number of stations. Furthermore, the entire data acquisition and processing system, which has changed over the years, is currently also highly robust. After the huge number of studies on the 1976 seismic sequence and on the regional seismicity developed in the 1970s and 1980s, the present paper illustrates a comprehensive work on the subject since the beginning of the 21st century. With this work, we take up the thread and analyse the evolution of seismicity in the first two decades of the 21st century (2000-2021). As part of the study, we took a retrospective look at the qualitative development of the data provided by OGS over time, basically focusing on the earthquake catalogue obtained by the network recordings and developing a new relation for calculating the duration magnitude..