Correlation of soil conditions with seismic damage of structures in Craiova, Romania

This study is focused on an evaluation of the correlation between the soil conditions and the seismic damage observed after the Vrancea March 4, 1977 intermediate-depth earthquake in Craiova, Romania. A significant number of existing studies in the literature have focused on the evaluation of damage for Bucharest, but the effects of the 1977 earthquake in Craiova have been very rarely discussed and presented. Craiova was the second city in Romania after Bucharest in terms of building damage and casualties as a result of the 1977 Vrancea seismic event, even though it is situated at a considerable distance (more than 250 km) from the epicenter. The 1977 event affected old low-rise masonry structures located in the central part of the city, as well as low-rise unreinforced masonry structures built after 1950. The soil conditions are evaluated based on a recently compiled collection of geological, geotechnical, and ground motion data from the study area. No correlation between the earthquake observed damage and the number of standard penetration test (SPT) blows at a depth of 6 m or the soil layer at a depth of 3 m can be inferred from the available data. Moreover, the analyses show practically no influence of the terrain slope on the ground motion amplitudes for Craiova, which is situated on the left bank of Jiu River. The vulnerability characteristics of unreinforced masonry structures from Craiova and other cities are also evaluated in this study. The relative frequencies of unreinforced masonry structures having increased damage degrees is significantly larger for the Iasi and Craiova data sets. Finally, an estimation of the peak ground accelerations in four cities in Romania is evaluated based on the damage of unreinforced masonry structures.