Pamukkale Univ Muh Bilim Derg. Ahead of Print: PAJES-75505 | DOI: 10.5505/pajes.2024.75505

Stress field analysis of the Simav Basin

Nihan Hoskan
Istanbul University-cerrahpaþa, Faculty Of Engineering, Department Of Geophysical Engineering, Istanbul

In this study, the stress tensor analysis of the Simav Basin was established by using the azimuth and plunge of the P- and T- axes which were obtained from the focal mechanism solutions of 59 earthquakes compiled from various sources. The results obtained in the study were calculated within the 95% confidence limit. Accordingly, for Simav Basin, principal stress axes are established (56/74), (109/10), (17/12) in degrees, respectively; R stress ratio was found to be 0.4. As a result of the regional analysis, the fact that the maximum stress axis is vertical indicates the general stress area in the region shows the NNE-SSW trending extension regime. The results obtained in this study were compared with the stress tensor results obtained by other researchers for the Simav Basin, and it was determined that the results obtained in this study were calculated more precisely. In addition, in this study stress analysis was also carried out for the southwest and northeast sections of the basin separately. 23 earthquakes were used for the stress tensor analysis of the southwest of the basin. Principal stress axes were attained (350/80), (127/7), (38/7), respectively; The R value was calculated as 0.45. The minimum principal axis was obtained as N38E. For the northeast of the basin, 36 earthquake data were used and principal stress axes were obtained (252/64), (109/21), (13/14) respectively. The stress ratio R was calculated as 0.35. It has been observed there is a 25-degree difference for the minimum principal stress axis between the southwest and northeast of the basin. It is thought this situation is compatible with the direction of the faults in the SW and NE part of the basin.

Keywords: Principal Stress Axes, Stress Tensor Analysis, Simav Basin

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Simav Havzasý'nýn gerilme alaný analizi

Nihan Hoskan
Ýstanbul Üniversitesi-Cerrahpaþa, Mühendislik Fakültesi, Jeofizik Mühendisliði Bölümü, Ýstanbul

Bu çalýþmada Simav Havzasý’nýn gerilme tensör analizi, çeþitli kaynaklardan derlenmiþ 59 depremin odak mekanizmasý çözümlerinden elde edilmiþ P- ve T- eksenlerinin azimut ve dalýmlarý kullanýlarak bulunmuþtur. Çalýþmada elde edilen tüm sonuçlar %95 güvenilirlik sýnýrlarý içerisinde hesaplanmýþtýr. Buna göre Simav Havzasý için asal gerilme eksenleri derece olarak sýrasýyla (56/74), (109/10), (17/12); R gerilme oraný ise 0.4 olarak bulunmuþtur. Bölgesel analiz sonucunda en büyük gerilme ekseninin düþey olmasý, bölgenin genel gerilme alanýnýn, KKD-GGB doðrultusunda açýlma rejimi olduðunu göstermektedir. Bu çalýþmada elde edilen sonuçlar, Simav Havzasý için diðer araþtýrmacýlar tarafýndan elde edilen gerilme tensor sonuçlarý karþlaþtýrýlmýþ, bu çalýþmada elde edilen sonuçlarýn daha hassas hesaplandýðý belirlenmiþtir. Ayrýca, bu çalýþmada havzanýn güneybatý ve kuzeydoðu kesimi için de ayrý ayrý gerilme analizi yapýlmýþtýr. Havzanýn güneybatýsýnýn gerilme tensör analizi için 23 adet deprem kullanýlmýþtýr. Asal gerilme eksenleri sýrasýyla (350/80), (127/7), (38/7); R deðeri ise 0.45 olarak hesaplanmýþtýr. Minimum asal eksen K38D olarak elde edilmiþtir. Havzanýn kuzeydoðusu için 36 adet deprem verisi kullanýlmýþ ve asal gerilme eksenleri sýrasýyla (252/64), (109/21), (13/14) elde edilmiþtir. R gerilme oraný, 0.35 olarak hesaplanmýþtýr. Havzanýn güneybatýsý ile kuzeydoðusu arasýnda minimum asal gerilme ekseni için 25 derecelik bir deðiþim olduðu görülmüþtür. Bu durumun, havzanýn GB ve KD kesimindeki faylarýn doðrultusu ile uyumlu olduðu düþünülmektedir.

Anahtar Kelimeler: Asal Gerilme Eksenleri, Gerilme Tensör Analizi, Simav Havzasý

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