THE STRUCTURAL COUPLING TO RUPTURE COMPLEXITY OF THE AFTERSHOCK SEQUENCE OF THE 2011 EARTHQUAKES IN LAKE VAN AREA (EASTERN ANATOLIA, TURKEY)

Öz

This study presents an analysis of the structural coupling to the two large destructive earthquakes that occurred in Lake Van area on October 23 (Mw 7.1), and November 9 (Mw 5.6), 2011, together with the azimuth-dependent distribution of the seismic activity and microseismicity clusters after the mainshocks, associated with the complex rupture processes of the aftershock sequence. The aftershock sequences after the two mainshocks were linked to the local crustal faults beneath Lake Van area, followed successively and produced unusually intense activity and significant damage in the area. The main purposes of this study are to document the spatial and temporal distribution and evolution of the October 23, 2011 aftershock hypocenters and the azimuth-dependent distribution of seismic activity, and to understand the structural character of the aftershock sequence using the distributional and evolutional patterns of the aftershock hypocenters. A total of 10,000 aftershocks were obtained from seismic data with a high signal-to-noise ratio collected over three years from October 23, 2011 to March 17, 2014. These aftershocks were relocated for the time periods from November 2011 through March 2012 to March 2014 and ≈ 5000 aftershocks were retained in the depth versus distance cross-sections to detect the clusters in the first step of study (November 2011-March 2012). The focal depth distribution of the aftershock clusters, the migration of hypocenter activity and microseismicity clusters were analyzed and the distributional patterns of the detected clusters were assessed using the geometric distribution of the aftershock hypocenters. The spatial and temporal distribution of aftershocks reveals interesting key features of the deep rupture complexity of the Van earthquake. This study presents the results of the first detailed hypocentral observations and this is important data for future seismic hazard analyses in the study area.

Anahtar Kelimeler

• Lake Van
• Van Earthquake
• Aftershock Sequence
• Microseismicity
• Clusters

VAN GÖLÜ BÖLGESİNDE 2011 YILI DEPREMLERİNİN ARTÇI ŞOK SERİSİ KIRILMA KARMAŞIĞINA YAPISAL BAĞLANTI(DOĞU ANADOLU, TÜRKİYE)

Öz

Bu çalışma, Van Gölü alanında gerçekleşen, 23 Ekim Van (Mw 7.1) ve 9 Kasım Edremit (Mw 5.6) 2011 yılı depremleriyle, artçışok kırılma karmaşığına bağlı olarak, anaşok sonrası oluşan küçük deprem kümelerinin ve genel sismik hareketliliğin, azimuta bağlı değişimini dikkate alarak kurulan yapısal ilişkinin bir analizini sunmaktadır. Her iki anaşoktan sonra oluşan artçışok serileri, Van Gölünün altında bulunan kabuk kökenli faylarla ilişkilendirilmiş ve ardarda olmak üzere, sıradışı yıkıcı bir etki oluşturarak, bölgede çok önemli bir zarara neden olmuşlardır. Bu nedenle, çalışmamızın temel amacı, 23 Ekim 2011 artçışok odak derinliklerinin zamana, mekana ve azimuta bağlı olarak dağılımını ve dağılım sürecini göstermek ve aynı zamanda, artçışok odak derinliklerini kullanarak, artçışok serilerinin yapısal karakterini anlamaktır. Bu çalışmada, yaklaşık 10.000 artçışok verisi, 23 Ekim 2011 ve 17 Mart 2014 tarihleri arasında 3 yıl süreyle kaydedilen, sinyal gürültü oranı yüksek deprem katalogundan elde edilmiştir. Bu artçışok veri seti, 2011 Kasım ve 2014 Mart tarihleri arasında yeniden yersel olarak konumlandırılmış ve bu çalışmanın ilk aşamasını teşkil eden, yaklaşık 5000 adet artçışok verisi, derinlik-uzaklık profil kesitlerinde, deprem kümelenmelerini tespit edebilmek için kullanılmıştır (Kasım 2011-Mart 2012). Böylece, artçışok kümelenmelerinin derinlik dağılımı, deprem odak derinliklerin hareketi ve küçük deprem kümelenmelerinin analizi gerçekleştirilmiştir ve ayrıca, artçışok odak derinliklerinin geometrik dağılımı kullanılarak, tespit edilmiş deprem kümelenmelerinin dağılım geometrilerinin analizi yapılmıştır. Artçışokların zamanda ve mekandaki dağılımları, Van depremini oluşturan fayın derinlerdeki kırılma karmaşasına dair, çok ilginç temel özelliklerini açıkça göstermiştir. Bu çalışma, ilk kez, deprem odağı analizi detaylı gözlem sonuçlarını vermektedir ve bu veri sonuçları, çalışma alanında, gelecekteki olması muhtemel deprem hasar analizleri için çok önem arz etmektedir.

Anahtar Kelimeler

• Van Gölü
• Van Depremi,
• Artçışok Sekansı
• Mikrosismisite
• Kümeler

Kaynakça

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