عنوان مقاله [English]
In general, seismic attenuation is caused by a combination of both scattering and intrinsic mechanisms. Scattering redistributes wave energy within the medium but does not remove energy from the overall wave field. In contrast, intrinsic attenuation mechanisms convert wave energy to heat through friction, viscosity, and thermal relaxation processes. The frequency-domain spectral decay method is employed to estimate frequency dependence value of Qs.
We used foreshock, main-shock and aftershock of Darb-e-Astane earthquake acceleration data with magnitude of 5.1, 6.1 and 4.9 for estimation at 1.5, 3, 6, 12 and 24 Hz central frequencies, respectively. The estimated average frequency dependence shear wave quality factor gives the relation. Shear wave quality factor are increasing from 156 to 592 at frequency band of 1-2 Hz and 16-32 Hz, respectively.
The Q0 value with frequency for this area is similar to those obtained for similar tectonically active regions in the world.