Seismological and Seismotectonic Characteristics of Earthquake Swarm in the Southern Nisyros Basin of the Aegean Sea

Öz

In this study, the temporal and spatial characteristics of the seismological parameters of the earthquake swarm occurred in the NE-SW direction on the Southern Nisyros Basin in east of the Aegean Cycladic Volcanic Arc between 1 April 2021 and 4 October 2021 was investigated. The focal mechanism solutions of 20 earthquakes with magnitude ML≥4.0 between the relevant dates show that the NW-SE direction tectonic extension is active throughout the basin. It has been determined that the normal faults controlling both sides of the basin are responsible for the swarm. The completeness magnitude representing the earthquake swarm was Mc=2.7, and the Gutenberg-Richter (G-R) equation was found to be LogN(ML)=0.86*ML-5.55 for the annual a-value. In the comparison of the temporal and spatial patterns of the earthquake activity and G-R variables in the region before and after April 1, 2021, the seismicity patterns and G-R values showed significant differences. It was observed that the earthquake swarm after 1 April 2021 occurred in an area between low b-value (high stress) and high b-value (low stress) that developed in the previous period.

Anahtar Kelimeler

• Earthquake swarm
• Extensional tectonics
• Completeness magnitude
• b-value
• Active fault

Ege Denizi Güney İncirli Havzası Deprem Fırtınasının Sismolojik ve Sismotektonik Özellikleri

Öz

Bu çalışmada, Ege Kiklad Volkan Yayı'nın doğusunda yer alan Güney İncirli Havzası’nda 1 Nisan 2021-4 Ekim 2021 tarihleri arasında KD-GB doğrultusunda oluşan deprem fırtınasının sismolojik özelliklerinin zaman ve mekânda değişimi incelenmiştir. İlgili tarihler arasında büyüklüğü ML≥4.0 olan 20 depremin odak mekanizması çözümleri, KB-GD yönündeki tektonik genişlemenin havza boyunca aktif olduğunu göstermektedir. Havzanın her iki tarafını denetleyen normal fayların deprem fırtınasından sorumlu olduğu saptanmıştır. Deprem fırtınasını temsil eden tamlık büyüklüğü Mc=2.7, Gutenberg-Richter (G-R) denklemi ise yıllık a-değeri için LogN(ML)=0.86*ML-5.55 olarak bulunmuştur. 1 Nisan 2021 öncesi ve sonrası dönemde bölgedeki deprem etkinliğinin ve G-R değişkenlerinin zamansal ve mekânsal dağılımları kıyaslandığında, depremsellik örüntüleri ve G-R değerleri önemli farklılıklar göstermiştir. 1 Nisan 2021 sonrası deprem etkinliğinin daha önceki dönemde gelişen düşük b-değeri (yüksek gerilim) ve yüksek b-değeri (düşük gerilim) arasında kalan bir alanda oluştuğu gözlenmiştir.

Anahtar Kelimeler

• Deprem fırtınası
• Genişleme tektoniği
• Deprem büyüklüğü tamlığı
• b-değeri
• Aktif fay

Kaynakça

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