Orta Anadolu’da kabuğa ait sismik P ve S dalga hızı yapısının belirlenmesi

Yıl 2019, Cilt: 25 Sayı: 6, 775 - 784, 25.11.2019

İbrahim Hakan Demirsıkan Şakir Şahin , Erdinç Öksüm

Öz

Bu
çalışmada, Orta Anadolu’da yerel depremlerin varış zamanlarından hareketle
Poisson oranı Tomografisi metodu kullanılarak üç boyutlu

(3-B) hız yapısını belirlenmiştir. Bu çerçevede, toplam 27.141 adet depreme ait
109.740 adet P dalgası ve 102.934 adet S dalgası varış zamanı verisi
kullanılmıştır. Depremler Boğaziçi Üniversitesi, Kandilli Rasathanesi ve Deprem
Araştırma Enstitüsü’ne (KRDAE) bağlı Ulusal Pasif Hareket Sismik Ağı’na bağlı
istasyonlar tarafından kaydedilmiştir. İnceleme alanında bulunan deprem
istasyonları ve deprem merkez üssü dağılımı, elde edilen Vp ve Vs hız
dağılımının 40 km’ye kadar güvenilir sonuç verdiğini göstermektedir. Dama
tahtası (Checkerboard) çözünürlük testi ve ışın yolu dağılımları bu durumu
doğrulamaktadır. Tomografik sonuçlar, Orta Anadolu’da kabuk ve üst mantoda
yanal heterojenliklerin varlığına işaret etmektedir. Depremlerin bölgedeki
karmaşık tektonik ve jeolojik yapıdan dolayı genel olarak sismik hızın düştüğü
alanlarda oluştuğu dikkati çekmektedir. Düşük veya yüksek hız değerlerine sahip
olan tüm bölgelerin gerilme enerjisi birikimi için potansiyel alanlar olduğunu
görülmektedir. Elde edilen P ve S dalga hızı modelleri, Orta Anadolu'daki
mevcut sismotektonik yapıyı net bir şekilde ortaya koymaktadır.

Anahtar Kelimeler

P ve S dalga hızları, Sismik tomografi, Orta Anadolu, Sismik hız

Determination of seismic P and S wave velocity structure of crust in Central Anatolia

Öz

In
this study, the three-dimensional (3-D) velocity structure was determined by
Poisson ratio Tomography method based on the arrival time of local earthquakes
in Central Anatolia. For this purpose, 109.740 P-wave and 102.934 S-wave
arrival time data from 27.141 earthquakes were used. Earthquakes were recorded
by stations related to the National Passive Motion Seismic Network of Bogazici
University, Kandilli Observatory and Earthquake Research Institute (KOERI).
Distribution of the stations and earthquake epicenters shows that the Vp and Vs
velocity model yield reliable results up to 40 km depth. Checkerboard
resolution test and ray path distributions confirm this situation. Tomographic
results indicate the presence of lateral heterogeneities in the crust and upper
mantle in Central Anatolia. It is remarkable that the earthquakes occur in
areas where the seismic velocity is low due to the complex tectonic and geological
structure in the region. The results of the study show that all regions with
low or high seismic velocities are potential areas for the accumulation of
stress energy. Resulting P- and S-wave velocity models clearly show the
existing seismotectonic structure in Central Anatolia.

Anahtar Kelimeler

P and S wave velocity, Seismic tomography, Center Anatolia, Seismic velocity

Kaynakça

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