Failure mechanism of historic churches in Gorj county for shallow seismic action

Abstract

Two major shallow earthquakes hit Gorj county in Romania on the 13th and 14th of February 2023, one had a magnitude of ML = 5.2 at a depth of 17 km, while the second earthquake had a magnitude of ML = 5.7 and a depth of 6 km.Considering that Romania is a very religious country, it is home to several beautiful and historic churches, some of which are near the epicenter of these earthquakes and were affected and damaged. This study also provides useful details about the particular failure mechanism of such buildings subjected to shallow earthquakes with a large vertical component.The paper focusses on the analysis of six orthodox churches, likely to be among the most affected in the area. The analysis aims to assess and present the particular failure mechanism of these churches and to highlight the importance of vertical components in seismic actions. All churches are built with unreinforced masonry and are close to the epicenter of the earthquake, at distances between 4.4 and 12 km. Each building has a detailed overview of the vertical and horizontal cracks aiming to confirm the importance of vertical seismic components which in reality represents a dominant parameter in the near-field areas, despite the fact that are usually neglected in the seismic design.The observed failure mechanism confirms the division of the churches in several independent structural portions (indicated as rigid blocks) when subjected to shallow seismic actions.