The strong ground motion and structural response analysis of 06 February 2023 Pazarcık and Elbistan earthquakes (Mw 7.7 and 7.6): a Case study for Malatya-Türkiye, Eastern Anatolia

Abstract

A major event with a magnitude of 7.7 (Mw) located in Pazarcık district of Kahramanmaraş on February 6, 2023. Approximately nine hours later, a second earthquake with a magnitude of 7.6 (Mw) located in the Elbistan region of Kahramanmaraş, approximately 100 km from the first earthquake according to the Disaster and Emergency Management Presidency (AFAD). These two earthquakes and the subsequent aftershocks caused many deaths, destruction and severe damage in areas close to the East Anatolian Fault Zone. The seismological and structural observations applied in the Malatya, one of the provinces affected by earthquakes, are presented in this study. For this purpose, acceleration data recorded at the strong motion station located in Malatya province and operated by the AFAD were examined. The seismic stations located in the Kale, Doğanşehir, and Akçadağ districts, located close to the province of the Malatya, were examined for the peak ground acceleration, the peak ground velocity, and the peak ground displacement for each station. Additionally, the spectral acceleration and the Arias intensities were calculated, also. The highest acceleration among these three stations in the Pazarcık earthquake was observed as approximately 0.16 g at station 4414 in the Kale district, and in the Elbistan earthquake, approximately 0.45 g at station 4406 in the Akçadağ district. Since the accelerations of the main shocks were not recorded at the stations in the Malatya city center, both the peak ground acceleration and the spectral acceleration values were predicted by using the ground motion prediction equations (GMPEs). The largest ground accelerations were predicted between 0.15 and 0.2 g for the Pazarcık earthquake and 0.3–0.4 g for the Elbistan earthquake in the Malatya province, also by using GMPEs, for different soil types. The peak ground acceleration that can be produced by DD-2 (the earthquake with a probability of 10% of exceed in 50 years) earthquakes in the center of the Malatya, is 0.361 g according to the Türkiye Building Earthquake Code 2018 (TBEC 2018). The Kahramanmaraş earthquakes (Mw 7.7 and 7.6) caused heavy damage to the structures in Malatya center because they exceeded the maximum ground acceleration value that could be produced according to the 2018 Türkiye Earthquake Hazard Maps (TEHM 2018). The results of the time-domain analysis applied to a collapsed building in the center of Malatya showed the necessity of obtaining site-specific earthquake spectra and making building designs and performance analyses by taking into account the structure-soil interaction. Taking these situations into consideration, it is expected that the building designs to be made based on the calculation of the largest spectrum acceleration values that may occur due to an earthquake in the worst ground conditions in the center of Malatya will be safer against earthquakes.