Dinar' da zemin büyütmesi ve 1 Ekim 1995 depreminde gözlenen hasarla ilişkisi

Bu çalışmada 1 Ekim 1995'de meydana gelen Dinar depreminin artçı şokları kullanılarak Dinar'da kurulmuş 5 istasyonda Klasik Spektral Oran,(KSO) ve Yatay/Düşey Spektral Oran (YDSO) yöntemleri ile zemin büyütmeleri hesaplanmıştır. Çalışma sonuçlarına göre, KSO yöntemi ile hesaplanan büyütmeler YDSO yöntemine göre 2-3 kat daha büyüktür. YDSO yönteminin özellikle büyütmelerde başarısız kalmasının ana nedeni, düşey bileşen kayıtlarının varsayılanın aksine yerel zemin koşullarından etkilenmesidir. Bu çalışmada Dinar Ovası içinde yer alan istasyonlarda düşey bileşendeki büyütme değerlerinin yatay bileşendeki büyütme değerlerine yakın olduğu görülmüş ve ova içindeki istasyonlarda 8 katına varan büyütmeler belirlenmiştir. Bu istasyonlarda zemin hakim titreşim periyodu 0.43-0.5 s (2-2.3 Hz) civarındadır. Bu değer, Dinar'da en fazla hasar gören 4-5 katlı binaların doğal titreşim periyodu ile çakışmaktadır. Bu nedenle, oluşan hasarda zemin büyütmeleri ve rezonans etkisinin önemli rol oynadığı sonucuna varılmıştır.

Site amplification in Dinar and relationship with damage observed on the October 1, 1995 earthquake

In this study, site amplifications at 5 stations located in Dinar were estimated with the aid of Classical Spectral Ratio (CSR) and the Horizontal-to-Vertical Spectral Ratio (HVSR) methods by using the records of the aftershocks of the October 1, 1995 Dinar earthquake. The results of the study suggested that site amplifications estimated by using the CSR method were 2-3 times higher than those estimated by the HVSR method. The reason for this discrepancy is due to the vertical motion records which were also affected by local geological conditions. The results of this study indicated that amplifications on the vertical motion records were approximately equal to those on the horizontal motion records. The stations located in the Dinar basin have site amplifications up to 8 times. At these stations, predominant soil periods are between 0.43 and 0.5 sec (2-2.3 Hz) and very close to the natural periods of buildings which were extensively damaged during the Dinar earthquake of October 1, 1995. Therefore, it was concluded that site amplifications and resonance effect have played important role in the damages occurred in Dinar during the earthquake.

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