Damage Assessment of Historical Masonry Churches Subjected to Moderate Intensity Seismic Shaking

An earthquake of magnitude 4.3 MW struck Cosenza (Calabria region, South Italy) and its immediate area on 24 February 2020. Although no damage was reported to ordinary masonry buildings, the ancient masonry churches suffered widespread damage. The herein article presents an analysis of the failures suffered by monumental buildings (e.g., churches) following a moderate seismic action. The contribution is based on the in situ damage observation of 14 churches, with a dating ranging from the 12th to 20th century. The study consists of a first phase, in which the different damage modes are identified, describing their causes and effects, and a second phase that correlates the damage detected to the main parameters that influence the seismic response of the churches (geometric characteristics, boundary condition, masonry and floor organization, past interventions, etc.), regardless of the state of conservation that was discrete for all buildings before the telluric event. From the rapid visual survey, the “weight” of each seismic parameter on the type of damage detected was then established. The past “retrofitting” interventions were decisive in the response of the ancient structure, with particular regard to those that made an aggravation of seismic mass and an increase in stiffness.