Source parameters of the 2005-2008 Balâ-Sirapinar (central Turkey) earthquakes: Implications for the internal deformation of the Anatolian plate

Yeşim Çubuk*, Seda Yolsal-Çevikbilen, Tuncay Taymaz

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14 Atıf (Scopus)

Özet

Active tectonics of central Anatolia is mainly governed by the collision of the African, Arabian and Anatolian plates, which causes westward escape of Anatolia along the North and East Anatolian Fault zones, and the counterclockwise rotation of the Kirşehir block with insignificant internal deformation. The formation of the present-day tectonic processes in this region can be deduced from geophysical prospecting and seismological data. Although the seismicity in central Anatolia is distinctively lower than that in the northern and eastern parts of the Anatolian plate, small and moderate earthquakes (2.5≤Mw≤6.0) mostly occurred in the region in the past decades or so. For example, intense earthquake activity was observed in the Balâ-Afşar-Sirapinar (Ankara, central Anatolia) region in the period of 2005 to 2008 with destructive earthquakes of July 30, 2005 (Mw=5.2); December 20, 2007 (Mw=5.7) and December 26, 2007 (Mw=5.6). Therefore, these earthquakes are crucial to analyze the shallow crustal deformation in the central Anatolian block. In the present study, we obtained source parameters of 2005-2008 earthquake sequence using the regional moment tensor (RMT) inversion method. We analyzed complete broad-band waveforms recorded at near-field distances (0.45°≤δ≤3.6°). Our results reveal NW-SE directed right-lateral strike-slip faulting and NE-SW directed left-lateral strike-slip faulting mechanisms, which are clearly correlated with the conjugate fault systems in the Balâ-Afşar-Sirapinar region. However, some earthquakes also have E-W directed normal faulting components. We suggest that the major characteristics of 2005-2006 and 2007-2008 earthquake activity could have been dominantly associated with left-lateral and right-lateral strike-slip faulting mechanisms, respectively. The seismogenic depth is found to be about 8-10km. This result implies that earthquakes in the study region occurred mostly in the upper crust, which accommodates the strain by brittle deformation. Furthermore, our results are consistent with neotectonic features and available geophysical data (e.g., gravity, aeromagnetic and paleomagnetic) reported by previous studies. It may be envisioned that the joint interpretation of earthquake source parameters with those observations will shed light into the complex deformation processes for future studies.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)125-153
Sayfa sayısı29
DergiTectonophysics
Hacim635
DOI'lar
Yayın durumuYayınlandı - 18 Kas 2014

Bibliyografik not

Publisher Copyright:
© 2014 Elsevier B.V.

Finansman

This study is part of the M.Sc. Thesis by Çubuk (2010) which has been supported by İstanbul Technical University Research Fund (İTÜ-BAP) , and partly funded by Turkish National Scientific and Technological Foundation (TÜBİTAK) , project no: ÇAYDAG-107Y288 . We would like to thank Kandilli Observatory and Earthquake Research Institute (KOERI-UDIM) for providing regional earthquake data used. Tuncay Taymaz thanks İTÜ-BAP, TÜBİTAK, Turkish Academy of Sciences (TÜBA) in the framework for Young Scientist Award Program (TÜBA-GEBİP 2001), and Alexander von Humboldt-Stiftung (AvH) for partial funding. Careful reviews by two anonymous referees resulted in considerable improvement to an earlier version of this manuscript. We are particularly indebted to the Editor-in-Chief Rob Govers and Guest Editor İbrahim Çemen for their judicious insightful remarks. The authors benefited from TDMT_INVC software developed by Douglas S. Dreger. Generic Mapping Tools (GMT; Wessel and Smith, 1998 ), SAC2000 software ( Goldstein and Snoke, 2005; Goldstein et al., 2003 ) were used to prepare figures and to process conventional earthquake data. The authors are grateful to Abdullah Ateş and T. Serkan Irmak for their comments at the earlier stage of the manuscript.

FinansörlerFinansör numarası
Turkish National Scientific and Technological Foundation
TÜBİTAKÇAYDAG-107Y288
Alexander von Humboldt-Stiftung
Türkiye Bilimler AkademisiTÜBA-GEBİP 2001
Istanbul Teknik Üniversitesi

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