Estimation of the quality factor of earthquake shear waves in the Seismic Province of Central and Eastern Iran

Having the seismic quality factor for each area and observing its changes due to occurrence of earthquake one could obtain some information concerning the inner structure of the earth and type of the soil in the area. Also the seismicity of the area could be acquired and using it the other parameters of an earthquake such as the velocity, magnitude etc. could be estimated. Recently the Q factor has been introduced as a pre-indicator for an earthquake and any changes of it could be a sign of earthquake occurrence in a place. Another application is generation of artificial accelerograms with higher accuracy. The aim of this article is calculation of the parameter of loss in Q factor in the seismic province of central-east Iran. In this respect first the previous research works were collected and studied and then by returning to the seismography and geology data banks of Iran and obtaining the needed information such as the seismic provinces of Iran and considering the accelerograms, the preliminary stages of the research were completed. In continuation, a total number of 419 earthquake records were employed for the central-east Iran zone. Baseline correction was first applied to the records and then the loss in the seismic quality factor was calculated using different methods. The research shows that loss in the seismic quality factor is to a large extend dependent upon the geological structure of the considered area. Also by increase in the shear wave velocity, the value of Q is decreased and by increase in the frequency, it would increase. Finally, the obtained relationships in this research were compared to other relationships in Iran and around the world. The proposed relationships in this research have a high efficiency with respect to other relationships for the central-east Iran zone.