Seismic-risk Mitigation for Brittle Museum Exhibits: Zagreb Experiences and Perspectives

Abstract

A strong M_L5.5 earthquake, that struck Zagreb in March 2020 caused significant damage to many buildings in the city centre and several museums had to be temporarily closed or relocated. However, what is sometimes being overlooked, are the many valuable museum collections that were severely damaged or irreparably destroyed due to the excessive seismic vibrations. Mainly due to a lack of financial resources and inadequate spatial conditions and capacities, even the most valuable and unique artifacts in Croatian museums are often insufficiently seismically protected. The paper addresses seismic risk mitigation for sculptures and other brittle artworks that are particularly sensitive to strong seismic accelerations. In contrast to the traditional rigid securing of protected objects, a novel technique, namely base isolation, benefits from their partially unrestrained sliding movement, which accommodates the ground vibrations. Although it has proven effective for many valuable sculptures around the world, it is however, extremely costly and mostly out of reach of the limited financial resources of the Croatian cultural sector. The experiences of the Zagreb museums and the implemented protection mechanisms before and after the March 2020 earthquake are being examined, with the aim of discussing feasible solutions that suit local means and circumstances.