THE SPATIAL ANALYSIS OF b-VALUES OF THE AREA BETWEEN BODRUM AND FETHIYE DISTRICTS, THE SOUTH-WESTERN ANATOLIA, TURKEY

Abstract

The estimation of the variation of the b-value, which is frequency distribution of a magnitude given in an earthquake data set of any region, is important parameter for interpretation of tectonic mechanism and seismic hazard assessment of that region. There is an inverse correlation between stress and b-value. The magnitude-frequency relationship is described by the well-known the Gutenberg-Richter relationship. The purpose of this paper is to investigate the recent seismicity of the region between the Bodrum and Fethiye, the south-western Anatolia in Turkey. A total of 27357 earthquake data is taken into account in this study in the period between 2004 to 2020 with magnitude (Ml) larger than 2. The majority of focal depths of earthquakes are concentrated between 0 and 33 km. The b-value in the Gutenberg-Richter relationship was estimated by the maximum likelihood method in this study. The estimated b-values range between 0.5 and 2 in the study region. While the lower b-values (0.5-1) are located at the SE of the study area (mainly the Beydağları unit), higher values (1-2) are trending on the west-east direction along the fault zones. The highest b-values in the study area are possibly related with the brittle lower-mid crust, thermal regime, normal faults and young basins bounded by these faults.

Keywords

• Guttenberg-Richter Relationship
• b-value
• Seismic Hazard
• The Maximum Likelihood Method.

BODRUM VE FETHİYE İLÇELERİ ARASINDAKİ BÖLGENİN b-DEĞERLERİNİN UZAYSAL ANALİZİ, GÜNEYBATI ANADOLU, TÜRKİYE

Abstract

Herhangi bir bölgenin deprem veri setinde verilen bir büyüklüğün frekans dağılımı olan b-değerinin değişiminin tahmini, o bölgenin tektonik mekanizmasının yorumlanması ve sismik tehlike değerlendirmesi için önemli bir parametredir. Gerilme ile b-değeri arasında ters korelasyon bulunmaktadır. Magnitüd-frekans ilişkisi, iyi bilinen Gutenberg-Richter ilişkisi ile tanımlanır. Bu makalenin amacı, Bodrum ve Fethiye ilçeleri arasındaki bölgenin (GB Anadolu, Türkiye) yakın zamandaki sismisitesini araştırmaktır. Bu çalışmada 2004-2020 yılları arasında magnitüdü (Ml) 2'den büyük toplam 27357 deprem verisi kullanılmıştır Depremlerin büyük çoğunluğunun odak derinlikleri 0 ile 33 km arasında yoğunlaşmaktadır. Bu çalışmada, Gutenberg-Richter ilişkisindeki b-değeri, maksimum likelihood yöntemiyle hesaplanmıştır. Hesaplanan b-değerleri çalışma bölgesinde 0.5 ile 2 arasında değişmektedir. Daha düşük b değerleri (0.5-1) çalışma alanının GD'sunda (esas olarak Beydağları birimi) yer alırken, batı-doğu yönelimli yüksek değerler (1-2) fay zonları boyunca yer almaktadır. Çalışma alanındaki en yüksek b değerleri muhtemelen kırılgan alt-orta kabuk, termal rejim, normal faylar ve bu faylarla sınırlanan genç havzalarla ilgilidir.

Keywords

• Gutenberg-Richter İlişkisi
• b-değeri
• Sismik Tehlike
• Maksimum Likelihood Yöntemi.

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