Damage classification of residential buildings in historical downtown after the ML5.5 earthquake in Zagreb, Croatia in 2020

Abstract A severe earthquake hit Zagreb on the 22nd of March 2020 (magnitude ML = 5.5, with an epicenter 7 kilometers north of the city center). During the COVID-19 lockdown, the event occurred and caused significant damage to the built environment and enormous disruption in everyday life. Brief facts about the Zagreb earthquake, the typology of buildings in the city, and the data collection after the quake itself are described. The paper focuses on post-earthquake assessment, damage classification, and failure patterns of residential buildings in Zagreb's old historical town, where masonry structures prevail. The earthquake critically damaged buildings that are important architectural achievements and ruptured Zagreb's historically recognizable city center. Furthermore, the data collected in the rapid post-earthquake assessment were analyzed and discussed. Graphical representations of damages are detailed and accompanied by photographs. This earthquake exposed Croatian building stock's vulnerability that should be mitigated as efficiently as possible in the coming years.