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GEOPHYSICAL RESEARCH LETTERS,
VOL. 30, NO. 24,
8041,
doi:10.1029/2003GL017390,
2003
Shear wave splitting in a young continent-continent collision: An example from Eastern Turkey
Eric Sandvol
Department of Geological Sciences, University of Missouri, Columbia, MO, USA
Niyazi Turkelli
Kandill Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey
Ekrem Zor
Kandill Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey
Rengin Gok
Kandill Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey
Tolga Bekler
Kandill Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey
Cemil Gurbuz
Kandill Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey
Dogan Seber
Institute for the Study of the Continents, Cornell University, Ithaca, NY, USA
Muawia Barazangi
Institute for the Study of the Continents, Cornell University, Ithaca, NY, USA
Abstract
We have determined the shear wave splitting fast polarization direction and delay time using data from the ETSE broadband
experiment (Eastern Turkey Seismic Experiment), a deployment of 29 broadband seismic stations across the collision zone of
the Arabian, Eurasian, and Anatolian plates. Our results show that the fast polarization directions are relatively uniform
and they exhibit primarily NE–SW orientations. No abrupt changes in anisotropy directions are observed across the main tectonic
units in the region: the Bitlis Suture (BS) and the North and Eastern Anatolian Fault zones. The fast polarization directions
are determined to be sub-parallel to the Anatolian, Arabian, and Eurasian absolute plate velocities, except for those stations
in the northeastern corner of the Anatolian Plateau. Observed delay times range from 0.7 to 2.0 seconds with an average value
of 1.0 second; the largest values are within the northern Anatolian Plateau which is underlain by an exceptionally low velocity
zone in the uppermost mantle. We interpret shear wave splitting as the vector difference of the Eurasian lithosphere and northeastern
or southwestern directed flow of the asthenospheric mantle. Comparisons of the polarization anisotropy with measurements of
Pn azimuthal anisotropy suggest vertical anisotropic layering except in those areas which are underlain by partially molten
uppermost mantle.
Received 23
March
2003;
accepted 21
May
2003;
published 10
September
2003.
Index Terms: 7200 Seismology; 7203 Seismology: Body wave propagation; 7218 Seismology: Lithosphere and upper mantle; 8102 Tectonophysics: Continental contractional orogenic belts.
Read Full Article (file size: 479670 bytes) Cited by
Citation: Sandvol, E., N. Turkelli, E. Zor, R. Gok, T. Bekler, C. Gurbuz, D. Seber, and M. Barazangi
(2003),
Shear wave splitting in a young continent-continent collision: An example from Eastern Turkey,
Geophys. Res. Lett.,
30(24),
8041,
doi:10.1029/2003GL017390.
Copyright 2003 by the American Geophysical Union.
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