Earthquake Forecast Verification for Northwestern Turkey

Öz

Seismic events have a pattern of recurrence in magnitude, time and space. Considerable effort is being spent to identify seismic patterns and successfully predict future earthquakes by using the recognized patterns. As a result of these intensive efforts, a variety of methods has been proposed. As the knowledge and experience in the field accumulated in parallel to the variety of the methods proposed, it was deemed necessary to test the performance of some of the highlighted methods, especially considering the wide reception of methods utilizing spatially smoothed seismicity (SSS), pattern informatics (PI) and Relative Intensity (RI). The performance of these methods in the prediction of future earthquakes has been selected for investigation.

The investigated area is the region bounded by 27⁰-33⁰ in longitudes and 39.8⁰-41⁰ in latitudes, well known for the North Anatolian Fault. The period of coverage has been selected such as to maximize the length with the minimum magnitude of completeness. As a result of such optimization, the period from 1973 to 2019 has been selected with minimum magnitude of completeness being determined as 3.8. In order to measure the relative performance of the methods, relative operating characteristic (ROC) analysis has been utilized. The method based on SSS has been adapted to the related ROC procedures, while the results of PI and RI methods are already suitable for the evaluation by ROC procedures.   

After the analysis was completed, according to the ROC procedures, none of the methods were singled out in forecast performance. However, when the ratio of hits versus total alarms and the area covered by the alarms, PI method outperforms two other methods by its efficiency. 

Anahtar Kelimeler

• Pattern informatics,relative intensity,earthquake forecast

Kuzeybatı Türkiye için Deprem Tahminleri Doğrulama Çalışması

Öz

Sismik hareketlerin büyüklük, zaman ve oluşum yerleri bağlamında, tekrarlama desenlerine sahip olduğu varsayılır. Sismik desenlerin belirlenerek geleceğe yönelik tahminlerin başarılı biçimde yapılabilmesi uğrunda dikkate değer ölçüde çaba harcanmıştır. Bu çabaların sonucu olarak, birçok yöntem geliştirilmiştir. Geliştirilen yöntemlerin çeşitliliği bağlamında bilgi ve deneyim artışı süregelmiş ve özellikle çoğunlukla kabul gören yöntemlerden, düzleştirmeye dayalı yöntemler (spatially-smoothed seismicity), desen bilgi (pattern informatics) ve göreli yoğunluk (relative intensity) yöntemlerinin yeni verilerle denenmesi gerekli olmuştur. Bahsi geçen yöntemler, deprem tahmin performansları açısından incelenmek üzere seçilmiştir.

İnceleme alanı 27⁰-33⁰ boylam ve 39.8⁰-41⁰ enlemleri arasında kalan, Kuzey Anadolu Fay Hattı ile ünlü bölge olarak belirlenmiştir. Geçmiş verilerin seçilmesi sırasında tamlık ölçütlerini sağlayan ve aynı zamanda en uzun dönemi kapsayacak şekilde belirlenmiştir. Bu kapsamda yapılan analiz sonucuna göre, tamlık ölçütünü sağlayan en küçük deprem büyüklüğü 3.8 olarak bulunmuş, tamlık ölçütlerine uyan dönem ise 1973 ile 2019 yılları arasında kalan dönem olarak belirlenmiştir. Tahmin yöntemlerinin başarısı ise göreli işletim ölçütü (ROC) analizi kullanılarak değerlendirilmiştir. Düzleştirme yöntemi uygulamaları ROC veri girdisi formatına göre uyarlanmış olup, PI ev RI yöntemleri is halihazırda ROC girdilerine uygun olarak veri üretmekte olduğundan herhangi bir uyarlamaya gerek kalmamıştır.

Çözümlemeler sonucunda, ROC değerlendirmeleri sonucunda yöntemlerden hiçbirisi öne çıkmamış ancak, başarılı tahminlerin toplam tahminlere ve tahminlerin kapladıkları alanlara göre değerlendirmesi sonucunda PI yönteminin diğer iki yönteme göre daha verimli bir yöntem olduğu belirlenmiştir.

Anahtar Kelimeler

• Örüntü bilişim,göreli yoğunluk,deprem tahminleri,kuzey anadolu fay hattı

Kaynakça

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