P-Alıcı Fonksiyonları ve Rayleigh Dalgası Grup Hızları’nın Birleşik Ters Çözümü’nden Doğu Anadolu Fay Zonu’nun Kabuk ve Üst Manto Hız Yapısı

Abstract

Geçmişten günümüze, yoğun depremselliğin meydana geldiği Doğu Anadolu Fay Zonu (DAFZ) aktif bir plaka sınırıdır. Bu aktivite bölgenin jeodinamik yapısı ile kesinlikle ilişkilidir. Arap plakasının kuzeye ve Avrasya plakasının güneye hareketinden dolayı, Anadolu plakası saat yönünün tersi doğrultusunda batıya doğru kaçmaya teşebbüs etmektedir. Bu tektonik hareket, önemli tektonik yapıların gelişmesine sebep olmaktadır. Aktif plaka hareketleriyle ilişkili olarak, kuzey-doğuda Kuzey Anadolu Fayı ve güney-batıda Ölü Deniz Fayı ile kesişen Doğu Anadolu Fayı’nın S-dalgası hız yapısı bölgenin tektonik yapısını yorumlamada oldukça önemlidir. Bu çalışmada DAFZ boyunca sekiz adet geniş-bantlı deprem istasyonundan toplanan verilerin kullanılmasıyla, P-Alıcı Fonksiyonu ve Rayleigh dalgası grup hızı birleşik ters çözümü yöntemi uygulanmıştır. P-Alıcı fonksiyonları 3-bileşen geniş-bantlı sismometreler de kayıt edilen ve her istasyon için ayrı ayrı yaklaşık 80 adet tele-sismik depremin kullanılmasıyla elde edilmiştir. Diğer taraftan, Rayleigh dalgası grup hızı dispersiyon eğrileri için odak derinliği 50 km’den küçük ve moment magnitüdü 5.0’dan büyük 21 lokal deprem kullanılmıştır. Her istasyon için bu iki yöntemden elde edilen sonuçlar, kabuk ve üst-mantonun 1-Boyutlu S-dalgası hız yapısını belirlemek için birlikte ters çözüm işlemine tabii tutulmuştur. DAFZ boyunca, S-dalgası hız modelleri üst kabukta yani yaklaşık olarak 4-12 km derinliklerinde, düşük hızlı tabakaların varlığını göstermektedir. Bununla birlikte, istasyonlar boyunca Conrad süreksizliği 22 km derinliği civarındadır. Ayrıca, kabuk-manto geçişi yaklaşık olarak ~44 km derinliğindedir. Sonuç olarak, bu çalışma, incelenen bölgenin tektoniği ile uyumlu kabuk ve en üst manto S-dalgası hız yapısını ortaya koymaktadır.

Keywords

• Alıcı Fonksiyonları
• Rayleigh Dalgası Dispersiyonu
• Birleşik Ters Çözüm
• Kabuk Yapısı
• Kesme Dalgası Hızı
• Doğu Anadolu Fay Zonu

Crust and Uppermost Mantle Velocity Structure beneath Eastern Anatolian Fault Zone from Joint Inversion of P-Receiver Functions and Rayleigh Wave Group Velocities

Abstract

The Eastern Anatolian Fault Zone (EAFZ) is an active plate boundary where intense seismicity has occurred from past to present. This activity is related to the geodynamic structure of the region. Because of the Arabian plate northward motion and the Eurasian plate southward motion, the Anatolian plate has attempted to escape westward with anticlockwise rotation, caused the development of important tectonic structures. Concerning these active plate motions, the S-wave velocity structure of EAFZ intersecting the North Anatolian Fault Zone (NAFZ) in the northeast and the Dead Sea Fault Zone (DSFZ) in the southwest is important in interpreting the tectonics of region. The present study is conducted on the joint inversion of P-wave receiver functions and Rayleigh wave group velocities techniques using the data collected from eight broadband stations along the EAFZ. The P-receiver functions are analyzed using approximately eighty teleseismic events for each station, recorded by the three-component broadband seismometers. On the other hand, for the Rayleigh wave group velocity dispersion curves calculations twenty-one regional earthquakes are used, which have focal depth less than 50 km and bigger than moment magnitude Mw=5.0. The analyses obtained from these two techniques is jointly inverted to determine the 1-D S-wave velocity structure of crust and uppermost mantle for each station. The results of inversion indicate that the S-wave velocity models show that the low-velocity layers are identified within the approximately 4-12 km in the upper crust. Besides, the Conrad discontinuity is determined as the depth of ~22 km along with the seismic stations. Furthermore, the crust-mantle boundary is ~44 km depth along with the EAFZ. Consequently, this study yields the crustal and uppermost mantle S-wave velocity structure compatible with the regional tectonics of the studied region.

Keywords

• Receiver Functions
• Rayleigh Wave Dispersion
• Joint Inversion
• Crustal Structure
• Shear Wave Velocity
• Eastern Anatolian Fault Zone

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