Investigation of the Directivity Effect of the February 6th Kahramanmaraş Earthquakes Using Tp and Ground Motion Prediction Equations
摘要
On February 6, 2023, two devastating earthquakes occurred nine hours apart in southern Türkiye and northern Syria. The first earthquake occurred with a magnitude of M 7.7, where the epicenter is located in Pazarcık and the second one occurred with a magnitude of M 7.6, where the epicenter is located in Ekinözü-Elbistan. These earthquakes were followed by aftershocks of varying magnitudes. A total of 11 provinces, primarily Kahramanmaraş, Hatay, Adıyaman, Gaziantep, Malatya, and Adana, were severely affected. A total of over 55,000 lives were lost, more than 14.01 million people were affected, and over 75 thousand buildings received heavy/medium damage. In this study, the directivity effect of the earthquakes and the damage relationship are examined, since this behavior has a significant impact on the structural damage of buildings. To examine the directivity effect, the records of 344 seismic stations for the 7.7 magnitude earthquake and 383 seismic stations for the 7.6 magnitude earthquake were analyzed. Wavelet analysis was performed to investigate the pulse effect in ground motions. The pulse periods were calculated for each station record. The earthquake prediction equations were used to compare the peak ground acceleration and spectral acceleration values for stations within a 200 km radius to epicenter. The intensity parameters such as cumulative absolute velocity was also investigated. The relative story drift behavior of a reinforced concrete frame was examined as a damage indicator at different locations based on the station strong motion records where the pulse period was dominant and those exposed to the peak ground velocity. In this way, the directivity effect of the earthquakes and the distribution of damage were evaluated.