Seismic Vulnerability and Simplified Safety Assessments of Masonry Churches in the Ischia Island (Italy) after the 2017 Earthquake

ABSTRACT

On August 21st 2017 an earthquake of magnitude Mw = 3.9 occurred in the Ischia Island (Italy), causing numerous damages to ordinary and monumental buildings and two casualties. Immediately after the earthquake, teams from the Universities of Napoli Federico II and ‘Parthenope’, carried out inspections on the churches of the island in two phases: the first was developed in the post-emergency and was mainly aimed to assess the overall damage and the usability checks through the A-DC form, issued by the Italian Ministry of Heritage and Cultural Activity and Tourism (MiBACT); the second phase was preparatory to the vulnerability assessment of each church, carried out by filling in the second level form, issued by the Italian Group for the Defence against Earthquakes (GNDT). Based on the available data, a database made of 27 churches was created to individuate the most representative typologies, to perform a territorial vulnerability assessment, to carry out a detailed analysis of the recorded damages and to construct damage probability matrices. Moreover, for a homogenous class of churches, a predictive formulation of the mean damage was assessed and compared with other formulations available in the literature. Finally, simplified methods for assessing the seismic safety of the inspected churches were applied to the database, in order to confirm the homogeneity of the Ischia churches in terms of seismic vulnerability.

KEYWORDS:

• Damage
• masonry churches
• post-earthquake survey
• seismic safety
• seismic vulnerability

Acknowledgments

Authors want to acknowledge the Italian MiBACT, Department of Civil Protection and ReLUIS consortium for giving the possibility to help in the emergency phase and to analyse the gathered dataset. A special thank goes to all collaborators from the involved universities (Napoli Federico II, Napoli ‘Parthenope’) who passionately surveyed and judged all the inspected churches.

The research has been carried out within the activities of the national Reluis project 2019-2020 “MAppe di Rischio e Scenari di danno sismico (MARS) - Task 4.8 – Modelli e curve di fragilità delle chiese” and has also been funded by the University of Napoli ‘Parthenope’ with a grant within the call “Support for competitive research for the 2015–17 Period”.

Disclosure statement

No potential conflict of interest was reported by the authors.