Evaluation of 08 August 2019 Bozkurt (Denizli-Turkey, Mw 6.0) earthquake in terms of strong ground-motion parameters and Coulomb stress changes

An earthquake with a moment magnitude (Mw) of 6.0 and a focal depth of 11 kms occurred in Bozkurt (Denizli, Turkey) on 08 August 2019. In this study, the peak ground acceleration (PGA) values of the Bozkurt earthquake recorded at stations are compared with four different ground-motion prediction equations (GMPEs). Subsequently, the acceleration response spectrums belonging to three stations with PGA values of more than 50 gals are compared with both the GMPEs and the Turkish Building Earthquake Code. As a result of the conducted assessments, the values closest to the recorded PGA values are calculated with the AK14 equation. Additionally, it is observed that the response spectrums received from stations 2005 and 3205 achieved greater values than the TBEC 2018 design spectrums. In addition to these assessments, the stress tensor analysis is conducted for the area of the Bozkurt earthquake and principal stresses in parallel with the normal faulting are observed. The stress variations before and after the Bozkurt earthquake are examined with the Coulomb stress analysis. The focal mechanism data belonging to 12 earthquakes that occurred between 1965 and 2019 are utilized to model the variation of the stress before the mainshock, and it is observed that the Bozkurt earthquake occurred in the positive stress area. With post-mainshock stress variations, it is observed that the majority of the aftershocks occurred in the areas with high stress. The aftershocks generally occurred on the East-Southeast of the mainshock. Coseismic Coulomb stress variation is modelled using the fault focal mechanism solution calculated with the moment tensor solution using fault mechanism obtained by moment tensor inversion and the distribution of the earthquake epicenters is evaluated to be compatible. By modelling the stress variation, important information can be provided for earthquake hazard assessment studies. In addition, the reliability of earthquake risk mitigation studies can be further increased.

Automated summary

In this study, the Bozkurt earthquake in Turkey was analyzed by comparing the recorded peak ground acceleration (PGA) values with different ground-motion prediction equations (GMPEs). The stress tensor and Coulomb stress variations before and after the earthquake were examined, revealing that the mainshock occurred in a positive stress area and the majority of aftershocks occurred in areas with high stress. The seismic hazard assessment and earthquake risk mitigation studies can benefit from these stress variations.