Laser scanning-based detection of morphological changes of a historical building occurred during a seismic sequence: Method and Case study

A tall masonry building in an area hit by an earthquake could suffer of some damages whose detection and evaluation are necessary for both emergency management and planning of restoration works. A complete characterization of the health state of a potentially damaged structure requires an integration of data provided by several techniques, which could be impossible in earthquake emergency conditions. The duration of a seismic sequence can reach several months and the state of a tall building could change after each significant shock. Terrestrial laser scanning (TLS) allows a fast and contactless acquisition as well as an accurate geometric modeling of a building and therefore can be used to evaluate the seismic-induced changes, possibly related to damages. The results of a study based on TLS monitoring the 100-m high Asinelli tower (Bologna, Italy), which is a very important element of the Italian medieval cultural heritage, during the 2012 Emilia Romagna seismic sequence are provided and discussed here. This work focuses on both method and case study. It is aimed to show how much information, reliable and accurate, can be extracted in a quick and simple way under alert conditions. Moreover, the structural behavior of the tower is provided. Considerations about natural oscillations of a tower subjected to seismic activity are also provided.