Estimation of Coda Wave Attenuation in the East Anatolia Fault Zone, Turkey

In this study, the attenuation of coda waves Qc(f) has been estimated for different lapse times and frequencies in the East Anatolian Fault Zone (EAFZ) in Turkey using a single back-scattering model of S-coda envelopes. The data include 255 earthquakes recorded by ten stations. The frequency-dependent Qc values are estimated at central frequencies of 1.5, 3, 6, 8, 12, and 18 Hz using 20–30–40 s lapse time windows. Along this fault zone, the frequency-dependent Qc obtained for all data and lapse time is Qc = 57.5f0.82. The entire study area is divided into six subregions according to the magnitude of the earthquakes and the location of the fault segments. The estimated average frequency-dependent relation for all lapse times are; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{I}} \right)}} }} = 3 4. 3f^{0. 9 3} $$\end{document} for Bingöl–Karliova–Erzincan triple junction; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{II}} \right)}} }} = 56.3f^{0.71} $$\end{document} for Bingol–Lake Hazar segment; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{III}} \right)}} }} = 68.5f^{0.75} $$\end{document} for Lake Hazar–Sincik segment; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{IV}} \right)}} }} = 72.5f^{0.78} $$\end{document} Hazar–Sincik and Çelikhan–Gölbaşı faults; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{V}} \right)}} }} = 59.7f^{0.87} $$\end{document} for Kahramanmaras triple junction and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{{{\text{c}}_{{\left( {\text{VI}} \right)}} }} = 67.4f^{0.94} $$\end{document} for Amanos Range and Karasu Basin. The lowest Qc is determined between Bingol and Malatya. The highest Qc value is along Amanos Range. In addition, Qc values are calculated for each regions at different lapse times. The average Qc value of the study region varies from 53 ± 11 at 1.5 Hz to 498 ± 41 at 18 Hz for 20 s lapse time window, as its variation is from 116 ± 11 at 1.5 Hz to 749 ± 75 at 18 Hz of central frequency for 40 s lapse time window. The increase of Qc with lapse times changes from one subregion to another along the fault zone. The rate of increment is significantly higher in Bingöl–Karliova–Erzincan triple junction than in the other subregions. This rapid increase of low Qc values in the junction reaches the general attenuation characteristics of the fault at 40 s lapse time. Finally, the low Q0 and high n values can be attributed to the energy loss as a result of the heterogeneity and activity along the fault zone. The increase of Qc with frequency, lapse time may be related to heterogeneity decreases with depth. The rapid increase of Qc with depth in Bingöl–Karliova–Erzincan triple junction may be interpreted that the effect of the Northern Anatolian Fault Zone is effective in the upper crust is not so deep compared to EAFZ.