1:45 PM - 2:00 PM
[SSS09-06] Attenuation Characteristics of Strong Motions during the 2023 Turkey-Syria Earthquake and the comparison with other large crustal earthquakes
Keywords:Turkey-Syria earthquake, PGA, Near field ground motion
1. Introduction
On February 6, 2023, an earthquake of Mw 7.8 occurred in the East Anatolian Fault Zone (EAF), central and southern Turkey. This earthquake was followed by an Mw 7.5 earthquake, 9 hours after the Mw 7.8 earthquake. These earthquakes caused enormous damage in Turkey and Syria.
In this sstudy, based on currently available strong motion records and source fault information for the Mw 7.8 earthquakes, we investigated the attenuation characteristics of the peak ground acceleration (PGA), including records in the area very close to the seismic fault. The observation records of three recent large crustal earthquakes are also used to compare the level of ground motion for the Turkey-Syria earthquake.
2. data
The strong motion records used in this study have been published by Turkey Disaster and Management Authority (AFAD) on their website. We used the PGA values obtained at 271 observation stations, and the PGA is defined as the larger one of the two horizontal components. The fault line estimated by Milliner (2023) are used to calculate the closest distance from an observation station to the seismic fault (Clsd). The depth to the top of the fault was uniformly assumed to be 1 km, and the fault was assumed to be a vertical fault.
The three recent large crustal earthquakes, the 2002 Mw 7.9 Denali earthquake, the 2008 Mw 7.9 Sichuan earthquake, and the 2016 Mw 7.8 Kaikoura earthquake are also used in this study. The data for these earthquakes are provided by Ancheta et al. (2014), Bradley et al. (2017) and Si et al. (2010), respectively.
3. Results
Fig. 1 shows the attenuation characteristics of PGA for the Turkey-Syria earthquake. For comparison, the prediction by Si and Midorikawa (1999) are also plotted. The figure shows that the observed PGA are widely scattered. Especially, of the the 27 records within 10 km in Clsd, 17 records were within the range of the standard deviation of GMM by Si and Midorikawa (1999), but 5 records were below 200 cm/s2, which is much lower than other observation records at similar distances. Of the 11 observed PGA larger than the prediction of GMM within a distance of 40 km, it is confirmed that, 1 record was near the epicenter, and 9 records were distributed along the seismic fault located southwest of the epicenter.
On the other hand, in comparing the observed PGAs during the Turkey-Syria earthquake and other large crustal earthquakes, the observed PGAs of the 2002 Mw7.9 Denali earthquake and the 2016 Mw7.8 Kaikoura earthquake were confirmed within the variation range for those of the Turkey-Syria earthquake. In addition, the observed PGAs during the 2008 Mw7.9 Sichuan earthquake were also confirmed within the variation range for those of the Turkey-Syria earthquake within a distance of about 100 km, but the observed PGAs of the Sichuan earthquake has a stronger amplitude average at longer distances.
References: Milliner (2023): Caltech; Bradley et al. (2015), SRL; Ancheta et al. (2014): Earthquake Spectra; Si et al. (2010), 7thCUEE&5thICEE.
Acknowledgments: the authors thank Turkey Disaster and Management Authority (AFAD) for providing us the observation records.
On February 6, 2023, an earthquake of Mw 7.8 occurred in the East Anatolian Fault Zone (EAF), central and southern Turkey. This earthquake was followed by an Mw 7.5 earthquake, 9 hours after the Mw 7.8 earthquake. These earthquakes caused enormous damage in Turkey and Syria.
In this sstudy, based on currently available strong motion records and source fault information for the Mw 7.8 earthquakes, we investigated the attenuation characteristics of the peak ground acceleration (PGA), including records in the area very close to the seismic fault. The observation records of three recent large crustal earthquakes are also used to compare the level of ground motion for the Turkey-Syria earthquake.
2. data
The strong motion records used in this study have been published by Turkey Disaster and Management Authority (AFAD) on their website. We used the PGA values obtained at 271 observation stations, and the PGA is defined as the larger one of the two horizontal components. The fault line estimated by Milliner (2023) are used to calculate the closest distance from an observation station to the seismic fault (Clsd). The depth to the top of the fault was uniformly assumed to be 1 km, and the fault was assumed to be a vertical fault.
The three recent large crustal earthquakes, the 2002 Mw 7.9 Denali earthquake, the 2008 Mw 7.9 Sichuan earthquake, and the 2016 Mw 7.8 Kaikoura earthquake are also used in this study. The data for these earthquakes are provided by Ancheta et al. (2014), Bradley et al. (2017) and Si et al. (2010), respectively.
3. Results
Fig. 1 shows the attenuation characteristics of PGA for the Turkey-Syria earthquake. For comparison, the prediction by Si and Midorikawa (1999) are also plotted. The figure shows that the observed PGA are widely scattered. Especially, of the the 27 records within 10 km in Clsd, 17 records were within the range of the standard deviation of GMM by Si and Midorikawa (1999), but 5 records were below 200 cm/s2, which is much lower than other observation records at similar distances. Of the 11 observed PGA larger than the prediction of GMM within a distance of 40 km, it is confirmed that, 1 record was near the epicenter, and 9 records were distributed along the seismic fault located southwest of the epicenter.
On the other hand, in comparing the observed PGAs during the Turkey-Syria earthquake and other large crustal earthquakes, the observed PGAs of the 2002 Mw7.9 Denali earthquake and the 2016 Mw7.8 Kaikoura earthquake were confirmed within the variation range for those of the Turkey-Syria earthquake. In addition, the observed PGAs during the 2008 Mw7.9 Sichuan earthquake were also confirmed within the variation range for those of the Turkey-Syria earthquake within a distance of about 100 km, but the observed PGAs of the Sichuan earthquake has a stronger amplitude average at longer distances.
References: Milliner (2023): Caltech; Bradley et al. (2015), SRL; Ancheta et al. (2014): Earthquake Spectra; Si et al. (2010), 7thCUEE&5thICEE.
Acknowledgments: the authors thank Turkey Disaster and Management Authority (AFAD) for providing us the observation records.