Site effects exacerbate the building damages from Mw7.8 Turkey Earthquake, 2023

Abstract

Abstract It is well-known that the impact of site effects on ground motion is a crucial factor to consider for earthquake disaster protection and mitigation. On February 6, 2023, southeastern Turkey experienced two strong earthquakes with Mw7.0 or greater followed by multiple aftershocks, resulting in significant casualties and economic losses. Field investigations revealed that mid-rise and high-rise buildings in Kahramanmaras and Antakya both situated in the valley, suffered severe damage. In this paper, H/V technique is used to study how site effects affect ground motion and damage in two cities by using S-wave periods based on the records of historical strong motion response and the main earthquakes. The H/V spectral ratio indicates that the predominant frequency tends to be lower near the valley and higher toward the hill slope. The nonlinearity of the site was found to amplify the acceleration response spectrum within a certain range, exceeding the local structure defense standards. Additionally, the observed building natural vibration period and response spectrum indicate a higher likelihood of resonance occurrences in mid-rise and high-rise structures situated in areas of depression. The results demonstrate that site effects exacerbate earthquake damage in Kahramanmaras and Antakya.