Artçı Depremler Üzerinde Oluşan Gerilme Değişimlerinin Coğrafi ve İstatistiksel Dağılımlarının İncelenmesi

Deprem sırasında fay çevresinde oluşan statik gerilme değişiminin bir sonra meydana gelecek deprem veya depremlerin oluşumuna etki ettiği bilinmektedir. Bir depremin ardından oluşan ±0.1 bar (±0.01 MPa) mertebesindeki gerilme değişimi artçı şokların dağılımını etkileyebilmektedir. Halbuki büyük depremlerden sonra açığa çıkan daha büyük gerilmeler 200 km yarıçaplı bir alanda oluşacak artçı şok dağılımlarını mekânsal ve zamansal olarak da etkilemektedir. Bu çalışmada Küresel Centroid Moment Tensör (CMT) kataloğundan seçilen 116 adet M≥7 deprem kaynak olarak modellenerek çevresinde meydana getirdiği gerilme değişim alanlarına düşen artçı şok dağılımları incelenmiştir. Katalog üzerinde farklı zaman periyotlarında de test edilen analizlere göre, her bir ana deprem sonrası oluşan artçı şok dağılımı %58 ile %62 arasında gerilmenin arttığı alanlarda, %38 ile %42 arasında oluşan artçı şoklar ise, gerilme azalımı olan alanlarda meydana geldiği gözlenmiştir. Yapılan analizlere göre küresel çapta gerçekleşen gerilme difüzyonu ters faylanmalar vasıtasıyla gerçekleşmiştir. Depremler sonucunda oluşan artçı şokların %80’i ters faylanma mekanizmalı ana depremlerden meydana gelmektedir. Dolayısıyla, depremlerden sonra çevre faylarda meydana gelen gerilme değişimlerinin hesap edilmesiyle, sismik tehlike bölgeleri tespit edilebilmektedir.

Anahtar Kelimeler:

Küresel CMT Kataloğu, Omori Yasası, Coulomb Gerilme, deprem analizi

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