Seismic quiescence and magnitude-frequency statistics of current earthquake activity in the Central Anatolian Region (Turkey) and its vicinity

Öz

In this study, seismic quiescence and magnitude-frequency statistics of current seismic activity in and around the Central Anatolian Region of Turkey were achieved. Seismicity studies in this region have gained considerable importance due to the strong/large earthquake occurrences in recent years. b-value shows a tendency to decrease after 2002 and decreases from 1.58±0.03 to 1.25±0.05 at the beginning of 2019. Region-time distribution of b-value shows significant changes in NF and its vicinity along the south, west, northwest and southwest directions, among MFZ, KKFZ and KOFZ, in and around SRF and along its northwest direction, between SRF and EAFZ. Seismic quiescence regions at the beginning of 2019 consist the northwest ends of TGFZ and study area including AF, the northeast of SF, between SF and CAFS, the northeast parts of CAFS, the west of MF, between SRF and EAFZ, the southeast end of TGFZ, KKFZ and its vicinity, the southwest of Tuzgölü. Consequently, these regions may be considered as one of the most likely areas for future strong/large earthquakes.

Anahtar Kelimeler

• b-value,earthquake potential,seismic quiescence,seismic hazard

Orta Anadolu Bölgesi (Türkiye) ve civarındaki güncel deprem aktivitesinin sismik durgunluk ve magnitüd-deprem sayısı istatistiği

Öz

Bu çalışmada, Türkiye’nin Orta Anadolu Bölgesi ve civarındaki güncel deprem aktivitesinin sismik durgunluk ve magnitüd-deprem sayısı istatistikleri gerçekleştirilmiştir. Son yıllardaki güçlü/büyük deprem oluşumları nedeniyle bu bölgedeki depremsellik çalışmaları oldukça önem kazanmıştır. b-değeri 2002 yılından sonra bir azalma eğilimi göstermektedir ve 2019’un başında 1.58±0.03’ten 1.25±0.05’e düşmüştür. b-değerinin bölge-zaman dağılımları, güney, batı, kuzeybatı ve güneybatı yönleri boyunca NF ve civarında, MFZ, KKFZ ve KOFZ arasında, kuzeybatı yönü boyunca SRF ve civarında, SRF ile DAFZ arasında önemli değişimler göstermektedir. 2019 yılı başlangıcındaki sismik durgunluk bölgeleri, TGFZ’nin kuzeybatı sonlarını ve AF’yi içeren çalışma alanını, SF’nin kuzeydoğusunu, SF ile OAFS arasını, OAFS’nin kuzeydoğu kısımlarını, MF’nin batısını, SRF ile DAFZ arasını, TGFZ’nin güneydoğu sonunu, KKFZ ve civarını, Tuzgölü’nün güneybatısını içermektedir. Sonuç olarak, Bu bölgeler, gelecekteki güçlü/büyük depremler için en olası alanlardan birisi olarak düşünülebilir.

Anahtar Kelimeler

• b-değeri,sismik tehlike,deprem potansiyeli,sismik durgunluk,sismik tehlike

Kaynakça

1. Gutenberg B., Richter, C.F. Frequency of earthquakes in California, B. Seismol. Soc. Am. 34 185-188, 1944.
2. Scholz C.H. The frequency-magnitude relation of microfracturing in rock and its relation to earthquakes, B. Seismol. Soc. Am. 58 399-415, 1968.
3. Wyss M., Martirosyan A.H. Seismic quiescence before the M7, 1988, Spitak earthquake, Armenia, Geophysical Journal International 134(2) 329-340, 1998.
4. Wyss M., Habermann R.E. Precursory seismic quiescence, Pure Appl. Geophys. 126(2-4) 319-332, 1988.
5. Console R., Montuori C., Murru M. Statistical assessment of seismicity patterns in Italy: Are they precursors of subsequent events?, J. Seismol. 4 435-449, 2000.
6. Polat O., Gok E., Yılmaz D. Earthquake hazard of the Aegean Extension region (West Turkey), Turkish Journal of Earth Sciences. 17 593-614, 2008.
7. Katsumata K. Precursory seismic quiescence before the Mw = 8.3 Tokachi‐oki, Japan, earthquake on 26 September 2003 revealed by a re‐examined earthquake catalog, J. Geophys. Res. 116 B10307, 2011.
8. Öztürk S. Characteristics of Seismic Activity in the Western, Central and Eastern Parts of the North Anatolian Fault Zone, Turkey: Temporal and Spatial Analysis, Acta Geophysica. 59(2) 209-238, 2011.

9. Ali S.M. Statistical analysis of seismicity in Egypt and its surroundings, Arab. J. Geosci. 9, 52, 2016.
10. Öztürk S. Space-time assessing of the earthquake potential in recent years in the eastern Anatolia region of Turkey, Earth Sci. Res. J. 21(2) 67-75, 2017.
11. Rodriguez-Perez Q., Zuniga F.R. Imaging b-value depth variations within the Cocos and Rivera plates at the Mexican subduction zone, Tectonophysics. 734-735 33-43, 2018.
12. Chiba K. Spatial and temporal distributions of b-values related to long-term slow-slip and low-frequency earthquakes in the Bungo Channel and Hyuga-nada regions, Japan, Tectonophysics. 757 1-9, 2019
13. Bozkurt E. Neotectonics of Turkey-a synthesis, Geodinamica Acta. 14 3-30, 2001.
14. Özsayın E., Dirik K. Quaternary activity of the Cihanbeyli and Yeniceoba fault zones: İnönü-Eskişehir fault system, Central Anatolia, Turk. J. Earth Sci. 16 471-492, 2007.
15. Gökten E., Varol B. General geology of the region and seismic sources. In Başokur, A. (eds) Geological-geophysical-geotechnical properties of soils west of the city of Ankara and dynamic behavior, Ankara University, pp.12-32 (in Turkish), 2010.
16. Şaroğlu F., Emre O., Kuşcu O. Active fault map of Turkey, General Directorate of Mineral Research and Exploration. Ankara, Turkey, 1992.
17. Ulusay R., Tuncay E., Sönmez H., Gökçeoğlu C. An attenuation relationship based on Turkish strong motion data and iso-acceleration map of Turkey, Eng. Geol. 74(3-4) 265-291, 2004.
18. Wiemer S. A software package to analyze seismicity: ZMAP, Seismological Research Letters. 72(3) 373-382, 2001.
19. Reasenberg P.A. Second-order moment of Central California seismicity, 1969-1982, J. Geophys. Res. 90(B7) 5479-5495, 1985.
20. Wiemer S., Wyss M. Minimum magnitude of completeness in earthquake catalogs: Examples from Alaska, the Western United States, and Japan, B. Seismol. Soc. Am. 90(3) 859-869, 2000.
21. Utsu T. Aftershock and earthquake statistic (III): Analyses of the distribution of earthquakes in magnitude, time and space with special consideration to clustering characteristics of earthquake occurrence (1), Journal of Faculty of Science, Hokkaido University. Series VII (Geophysics) 3 379-441, 1971.
22. Frohlich C., Davis S. Teleseismic b-values: Or, much ado about 1.0, J. Geophys. Res. 98(B1) 631-644, 12993.
23. Mogi K. Magnitude-frequency relation for elastic shocks accompanying fractures of various materials and some related problems in earthquakes, Bulletin of the Earthquake Research Institute, Tokyo University. 40 831–853, 1962.
24. Wiemer S., Wyss M. Seismic quiescence before the Landers (M=7.5) and Big Bear (M = 6.5) 1992 earthquakes, B. Seismol. Soc. Am. 84(3) 900-916, 1994.
25. Katsumata K., Kasahara M. Precursory seismic quiescence before the 1994 Kurile Earthquake (Mw=8.3) revealed by three independent seismic catalogs, Pure Appl. Geophys. 155 43-470, 1999.
26. Joseph J.D.R., Rao K.B., Anoop M.B. A study on clustered and de-clustered world-wide earthquake data using G-R recurrence law, International Journal of Earth Sciences and Engineering. 4 178-182, 2011.
27. Aki K. Maximum likelihood estimate of b in the formula and its confidence limits, Bulletin of the Earthquake Research Institute. Tokyo University 43 237-239, 1965.
28. Çobanoğlu İ., Bozdağ Ş., Dinçer İ., Erol H. Statistical approaches to estimating the recurrence of earthquakes in the Eastern Mediterranean region, İstanbul Univ. Eng. Fac. Earth Sci. J. 19(1) 91-100 (in Turkish with English abstract), 2006.
29. Kahraman S., Baran T., Saatçı İ.A., Şalk M. The effect of regional borders when using the Gutenberg-Richter model, case study: Western Anatolia, Pure Appl. Geophys. 165 331-347, 2008.
30. Özmen B. Assessment of the statistical earthquake hazard parameters for the Central Anatolia region, Turkey, Arab. J. Geosci. 8 6341-6351, 2015.