mehdi zare - Engineering Geologist & Research Associate, Earthquake Reconnaissance Dept., II EES, Tehran, P.O.Box: ۱۹۳۹۵/۳۹۱۳,I.R.Iran
ali urumiehei - Assistant Professor of Engineering Geology, Engineering Geology Dept., Tarbiat-Modarres UniversityTehran, I. R. Iran

Selection of the strong ground motion parameters and the earthquake time-histories is of great importance for seismic resistant design of the engineered structures, In the case of paucity of the accelerometric data and when the network is not contained of sufficient accelerography stations, like Iran, more difficulties are existed for the optimized selections. The empirical method of selection of the seismic parameters is studied in a case study herein, with a special reference to the site geology. The method is evaluated in two different pairs of sites in northern Iran, where the strong motion records are obtained during the Manjil, Iran earthquake of June ۱۹۹۰ Finally six comments are suggested as some guidelines for selection of time-histories for the engineered sites.