Tracing Past Earthquakes Through the Analysis of Building Transformations in the Historic Center of Gerace

The historic center of Gerace, in Calabria (Italy), has suffered several earthquakes of various intensities over the centuries. These events have repeatedly damaged its buildings, which today appear largely stratified. Earthquakes can result in shifts and tilts in masonry or brickwork, displaced walls, warped floors, missing sections, and sometimes, a complete collapse of the structure; at the same time, they obviously can result in the consequent reparations—with reinforcements or integrations of the masonries for example—transformations—such as the introduction of new constructive techniques or new structural system—and reconstruction. Although earthquakes of various intensities probably left traces on buildings, it is not immediate or easy to recognize these signs and link them to the specific seismic event in Gerace. In the same way, it is mostly not possible to assert that the transformations present in buildings derive from post-earthquake modifications and transformations, or from other different reasons that have arisen over time. Starting from these considerations, this proposal aims to illustrate the development of analyzes on the morphological evolution of the buildings aggregates of the historic center. In particular, we want to face with a type of analysis that arises from evidence observable in the field, and that is therefore mostly based on visual investigations of the buildings. Given the scarcity of documentation, only in some cases is it possible to obtain confirmation from the archive documentation on what has been reconstructed. For this reason, in the historic center of Gerace, direct analyzes of buildings represent the main method with which to study the historical buildings. The in-depth knowledge of the selected cases had the objective of developing expeditious models that highlight the signs and construction phases that characterize the selected building sample, and which can thus suggest possible future collapse phenomena, this to be able to predict the possible behavior under future stresses.