09:00 〜 09:15
[S07-1-03] Estimation of site amplification using ground motion records at strong motion stations in Turkey
A strong ground motion network has been operated in whole of Turkey by AFAD (Prime Ministry Disaster and Emergency Management Authority, Turkey). Strong motion records from the observation have provided important data in understanding strong motion features and reasons of damage in many past earthquakes in Turkey. Many studies on local site effects in many areas in the country have been conducted using strong motion records, such as Avcilar area in the west Of Istanbul (Ozel et al., 2002).
In this study we have estimated site effects at the AFAD stations in whole of Turkey. Strong ground motion data observed during 754 earthquakes at 465 strong motion stations were used to estimate effects of source, propagation path and site amplifications using a spectral separation technique in the frequency domain at a frequency range of 0.5 to 20Hz. Since we used theoretical amplification of soil layers over the basement with an S-wave velocity of about 2km/s as similar to Ozmen et al. (2016), the estimated amplification factors in our analysis can be regarded as effects of all geological layers over the basement.
Q-values are slightly larger than those from previous studies. Most of the source spectra can be explained with the omega-square model. The amplifications at most of the sites in the central part of Turkey are small at all the frequency, while large amplification factors are found at sites in the south-western part of Turkey and along the east Anatolian fault. In particular the amplification factors are large at high frequency at some stations around the Marmara sea suggesting effects of shallow soil. We furthermore discuss relationships of the amplification factors with averaged S-wave velocity values in some depths at some of the stations.
In this study we have estimated site effects at the AFAD stations in whole of Turkey. Strong ground motion data observed during 754 earthquakes at 465 strong motion stations were used to estimate effects of source, propagation path and site amplifications using a spectral separation technique in the frequency domain at a frequency range of 0.5 to 20Hz. Since we used theoretical amplification of soil layers over the basement with an S-wave velocity of about 2km/s as similar to Ozmen et al. (2016), the estimated amplification factors in our analysis can be regarded as effects of all geological layers over the basement.
Q-values are slightly larger than those from previous studies. Most of the source spectra can be explained with the omega-square model. The amplifications at most of the sites in the central part of Turkey are small at all the frequency, while large amplification factors are found at sites in the south-western part of Turkey and along the east Anatolian fault. In particular the amplification factors are large at high frequency at some stations around the Marmara sea suggesting effects of shallow soil. We furthermore discuss relationships of the amplification factors with averaged S-wave velocity values in some depths at some of the stations.