Abstract

Coda quality factor (Qc) estimates for the Faryb region in the southeast Zagros have been obtained by using aftershock data of the Tiab earthquake of 28 February 2006, recorded within an epicentral distance of 100 km. More than 394 earthquakes were recorded by a local temporary network consisting of 9 short‐period stations installed for one month after 28 February 2006. Qc was estimated using the single‐backscattering model in frequency bands of 0.5–24 Hz. In this research, the spatial and temporal variation of Qc in the Sanandaj–Sirjan zone is studied. To explore the lateral variation, Qc is calculated for nine stations and in different parts of the covered area. The lowest values are derived in KALI station in the southern part and the higher value in BAGA station in the northern part, but generally there is an absence of significant lateral variation in coda Qc in the Faryab region. To investigate the attenuation variation with depth, Qc value was calculated for eight lapse times. The average frequency relation for this region is Qc=(28±1.1)f (1.14±0.01) at 5 s lapse time window length and Qc=(105±1.3)f (0.98±0.047) at 30 s lapse time window length. Qc increases with depth; however, the rate of increase of Qc is not uniform with depth in the study area. Beneath the Faryab region, the rate of increase of Qc is greater at depths less than 49 km (compared to larger depths), indicating a low attenuation structure at less than ∼49  km depth, which is the Moho depth in this region.

You do not currently have access to this article.