Akademik Veri Yönetim Sistemi
TECTONOPHYSICS, cilt.659, ss.53-62, 2015 (SCI-Expanded)
The attenuation of coda waves has been inferred for Central West Turkey, which is characterized by a very complex tectonic evolution. The selected dataset is composed of 440 waveforms from 228 local earthquakes with a magnitude range of 2.9-4.9. The coda quality factor (Q(c)) was estimated for five central frequencies (f(c) = 1.5, 3, 5, 7, 10 Hz) and eight lapse times (t(L), ranging from 25 to 60 s), based on the assumption of single isotropic scattering model. Estimated Q(c) values were strongly dependent on frequency and lapse time. The frequency dependence of Qc values for each lapse time was inferred from Q(c)(J) = Q(o)f(n) relationships. Q(o) values change between 32.7 and 82.1, while n values changes between 0.91 and 0.79 for the lapse times of 25 and 60 s, respectively. The obtained low Qo values show that the Central West Turkey region is characterized by a high seismic attenuation, in general. The whole region was divided into four subregions to examine spatial differences of attenuation characteristics. Obtained 1/Q(o) and n values versus the lapse time for each subregion implies the tectonic complexity of the region. Lapse time dependencies of attenuation and n values were also examined for subdatasets from two different ranges of event depth (h < 10 km and h >= 10 km) and distance (r < 40 km and r >= 40 km). High attenuation and its high frequency dependence for long distances manifest the elevation of isotherms and increasing heterogeneity with depth. This could be associated with the extensional intra-continental plate setting, forming regional tectonics in the back-arc area. (C) 2015 Elsevier B.V. All rights reserved.