Yalçın KALYONCUOĞLU, Osman UYANIK, Selda ALTUNCU, Elçin GEÇİM

GUTENBERG- RICHTER BAGINTISINDAKİ b DEĞERİNİN TESPİTİ İÇİN ALTERNATİF BİR METOT VE GÜNEYBATI TÜRKİYE'DE BİR UYGULAMASI

Çalışmada Güneybatı Türkiye’nin sismik riski ve sismisitesinin uzaysal dağılımı ele alınmıştır. Bu amaç için 1964–2002 yılları arasında bölgede meydana gelen M≥4 olan 722 adet deprem verisi kullanılmıştır. Sismisite parametrelerinin belirlenebilmesi ve haritalanması için çalışılan alan 169 alt bölgeye ayrılmıştır. Her bir alt bölge için, Gutenberg-Richter magnitüd-frekans bağıntısındaki b değeri en küçük kareler tekniği ve yeni bir alternatif metotla hesaplanarak doğrudan en küçük karelerden elde edilen sonuçlar ile karşılaştırılmıştır. Yeni alternatif metotta Gutenberg-Richter bağıntısındaki a parametresi sabit alınmıştır. Güneybatı Türkiye boyunca her iki teknik içinde b değeri farklı değişim göstermiştir. Yeni alternatif metot ile Güneybatı Türkiye’nin Doğusu yüksek b değeri gösterirken, Batı kanadında düşük b değerleri baskın olarak bulunmuştur. Son olarak, her iki teknikle de Poisson modeli kullanılarak çalışma alanı içerisinde M≥6 depremin 75 yıllık bir süreçte oluşma riski ve dönüş periyotları hesaplanarak haritalanmıştır. Her iki teknikle oluşturulan risk ve dönüş periyodu haritaları alternatif metotla oluşturulan b parametresi sismisite haritalarıyla oldukça uyumlu olarak bulunmuştur. Ayrıca, her iki teknikle de elde edilen risk ve dönüş periyotları bir biri ile tamamen uyumludur. Çalışma alanının Batı kanadında M≥6 bir depremin oluşma riski %90–95 ve dönüş periyodu da 15– 30 yıl olarak elde edilmişti

Anahtar Kelimeler:

Gutenberg-Richter b değeri, Sismik risk, Sismisite, Güneybatı Türkiye

AN ALTERNATIVE METHOD FOR THE ESTIMATION OF b-VALUE IN THE GUTENBERG-RICHTER RELATION WITH AN APPLICATION IN SOUTHWEST OF TURKEY

In this study, the spatial distribution of seismicity and seismic hazard is undertaken for the Southwest of Turkey. For this purpose, the earthquakes of magnitude of M≥4 which were occurred between 1964 - 2002 were used in Southwest of Turkey. For the estimation of seismicity parameters and its mapping, Southwest of Turkey is divided into 169 rectangular subregions. The b value from the Gutenberg-Richter frequency-magnitude distributions is calculated by least squares method with a new alternative method and compared with the results directly calculated by least squares method. The a value in the Gutenberg-Richter frequency-magnitude distributions is taken a constant value in the new alternative method. The b value shows different distributions along the Southwest of Turkey for both techniques. From the new technique, low b-values are dominant in the western part of the studying region, while higher b-values are present in the eastern part. Finally, the return period and occurrence probability risk of M≥6 earthquakes in 75 years were calculated using Poisson model for both techniques. Maps of the occurrence probability risk and return period showed a better consistency with the b parameters seismicity maps calculated from new method. Moreover, the return period and occurrence probability risk maps calculated from both techniques showed a better consistency,with each other. The occurrence probability risk and return period of M≥6 earthquake were calculated as %90-95 and 15-30 years, respectively, from the Poisson model in the western part of the studying region.

Keywords:

Gutenberg-Richter b value, Seismic risk, Seismicity, Southwest of Turkey,

PDF

___

Allen C.R., Amand P., Richter C.F., Nordquist J.M. (1965):“Relation Between Sismicity and Geological Structure In The S. California Region”, Bull. Seismol. Soc. 55, 752-797.
Bath M. (1983): “Earthquake Magnitude-Recent Research and Current Trends”, Earth. Sci. Rev. 17, 315-398.
Evernden J.F. (1970): “Study of Regional Seismicity and Associated Problems”, Bull. Seismol. Soc. Am., 60, 393-446.
Frohlich C., Davis S. (1993): “Teleseismic b-Values: or, Much Abouth 1.0”, J. Geopyhys. Res., 98, 631- 644.
Gutenberg B., Richter C.F. (1944): “Frequency of Earthquakes in California”, Bull. Seismol. Soc. Am., 34, 185-188.
Hazidimitriou P.M., Papadimitriou E.E., Mountrakis D.M., Papazachos B.C. (1985):”The Seismic Parameter B of The Frequency-Magnitude Relation and Its Association with The Geological Zones In The Area of Greece”, Tectonophysics, 120, 141-151.
IRIS (Incorporated Research Institutions for Seismology) www.iris.edu.
Ishomoto M., Lida K. (1939): “Observations of Earthquakes Registered with The Microseismograph Constructed Recently”, Bull. Earthq. Res. Inst., 17, 443-478.
Kijko A. (1988): “Maximum Likelihood Estimation of Gutenberg-Richter B Parameter For Uncertain Magnitudes Values”, Pure Appl. Geophys., 127, 573-579.
Kiremidjian A.S., Shah H.C. (1975): “Seismic Hazard Mapping of California”, The John A. Blume Earthquake Eng. Center, Report No.21, Dept. of Civil Engr., Stanford Univ.
Manakou M.V., Tsapanos T.M. (2000): “Seismicity and Seismic Hazard Parameters Evaluation in The Island of Crete and Surrounding Area Inferred from Mixed Data Files”, Tectonophysics, 321, 157-178.
Miyamura S. (1962): “Magnitude-Frequency Relations and Its Bearing to Geotectonics”, Proc. Japan. Acad., 38, 27-30.
Mogi K. (1967): “Earthquakes and Fractures”, Tectonophysics, 5, 35-55.
Mori J., Abercrombie R.E. (1997): “Depth Dependence of Earthquake Frequency-Magnitude Distributions in California”, J. Geopyhys. Res., 102, 15081-15090.
Olsson R. (1999): “An Estimation of Maximum b-Value in the Gutenberg-Richter Relation”, Journal of Geodynamics, 27, 547-552.
Pacheco J.F., Scholz C.H., Sykes L.R. (1992): “Changes in Frequency-Size Relationship from Small to Large Earthquakes”, Nature, 355, 71-73.
Papazachos B.C. (1974): “Dependence of the Seismic Parameter B on the Magnitude Range”, Pure Appl. Geophys., 112, 1059-1065.
Papazachos B.C. (1999): “An Alternative Method for A Reliable Estimation of Seismicity with an Application in Greece and the Surrounding Area”, Bull. Seismo. Soc., 89, 111- 119.
Scholz C.H. (1968): “The Frequency-Magnitude Relation of Microfracturing In Rock And Its Relation To Earthquakes”, Bull. Seismol. Soc. Am., 58, 399-415.
Shi Y., Bolt B.A. (1982): “The Standard Error of the Magnitude-Frequency B-Value”, Bull. Seismol. Soc. Am., 72, 1677-1687.
Tsapanos T.M., Galanopoulos D.G., Burton P.W. (1994): “Seismicity in the Hellenic Volcanic Arc: Relation between Seismic Parameters and the Geophysical Fields in the Region”, Geopyhys. J. Int., 117, 677-694.
Turcotte D.L. (1986): “A Fractal Model of Crustal Deformation”, Tectonophy, 132, 261-269.
USGS (United States Geological Survey) www.usgs.gov
Wang J.H. (1988): “B-Values of Shallow Earthquakes in Taiwan”, Bull. Seismol. Soc. Am., 78, 1243-1254.
Wang J.H. (1994): “On The Correlation of Observed Gutenberg-Richter’s B-Value and Omori's P-Value for Aftershocks”, Bull. Seismol. Soc. Am., 84, 2008-2011.
Wiemer S., Mcnutt S.R., Wyss M. (1998): “Temporal and Three-Dimensional Spatial Analysis of the Frequency-Magnitude Distributions Near Long Valley Caldera, California”, Geopyhys. J. Int., 134, 409-421.
Wiemer S., Wyss M. (1997): “Mapping The Frequency-Magnitude Distributions in Asperities: An Improved Technique to Calculate Recurrence Times”, J. Geopyhys. Res., 102, 15115-15128.