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چکیده
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The attenuation of seismic waves in the Zagros region (southwestern Iran) was investigated using seismic waveforms collected from 2006 to 2019. The selected data set consists of 6421 local earthquakes (3 < ML < 5.5) recorded at a permanent network composed of 36 seismic stations. The quality factor of seismic body waves was estimated using the extended coda normalization method. Estimated values for Qp and Qs at five central frequencies (1.5, 3, 6, 12, 18 Hz) are Qp(r≤100km)=(57.3±3)f(0.71±0.11) and Qs(r≤100km)=(72±4)f(0.8±0.06), respectively. We used Wennerberg’s (Bull Seismol Soc Am 83: 279–290, 1993) method to separate intrinsic and scattering attenuation. This study suggests that the values of Qsc and Qi are close to coda attenuation, which may arise from the complex tectonic nature of the Zagros. The estimated results of coda wave attenuation show the same results as the intrinsic and scattering attenuation, which suggests that this is the main cause of the coda decay. According to our results, the attenuation of seismic waves in the Zagros area is significant due to geological features such as hidden faults, numerous fractures, a sedimentary layer, the Gachsaran Formation, and Hormuz salt. Spatial variation in Q values reveals that the attenuation is higher in the northern parts of the region than in the southern parts. The results of this study are compared to other seismically active areas.
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