The propagation characteristics of the regional Sn shear waves have been mapped
to provide insight into the lithospheric structure of the Anatolian and Iranian
plateau and the surrounding regions. Thousands of regional earthquakes within
the distance range of 2–15 degrees were recorded by broadband and short
period stations located in Turkey and nearby regions, especially new data recorded
by 29 broadband stations in the Eastern Turkey Seismic Experiment network. The
propagation efficiencies of Sn were determined visually using their amplitude
and frequency content. Attenuation maps were
then tomographically constructed using the observed propagation efficiencies.
Our results confirm that Sn propagates efficiently in the uppermost mantle beneath
the Mediterranean Sea, the Black Sea, and the Caspian Sea and along the Zagros
fold and thrust belt. Sn is not observed in eastern Turkey, northwestern Iran,
or central Anatolia. In contrast to previous available studies, this study considerably
improved the mapped location of the boundaries between the zones of efficient
and attenuated Sn. Our results are best explained by an absence of lithospheric
mantle, or the presence of thin and hot lithospheric mantle beneath most of
the Anatolian and Iranian plateau.
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An edited version of this paper was published by AGU. © 2003 American Geophysical Union.
Figure 4. (a) Map showing Sn efficiency tomography results. Green lines are major tectonic boundaries and coast lines, black lines are national boundaries. (b) Resolution test using a synthetic checkerboard for extinction path length of 350 km (Q = 100).