The seismic risk studies in Iran are in the first stages. Till now, no catalog of strong motion accelerograms was existing in Iran , and no study has been conducted on the entire of the strong motion data. This thesis presents therefore the first study on the whole strong motion data-set in Iran. A first objective in this work was to establish a catalog of strong motion to assign to each record - of a satisfactory quality - a seismic event with known location and magnitude. Such correspondance was possible based on the international (NEIC, ISC, ... etc) or national seismologic catalogs, for 279 analog and digital accelerograms. For 189 other digital data, for which no teleseismic or local information was available, the hypocentral distance and the moment magnitude are estimated based on each record. A special attention was paid to site effects, choosing 50 strong motion stations of the national network, where there were a lot of records. A new classification for site effects is proposed - based on the H/V ratio - which is relatively simple, and more reliable than the previously proposed methods. Finally, the attenuation laws for different parameters of strong motion (such as Arms, Arias intensity, PGA, PGV, and PGD, energy, duration and the spectral ordinates) are obtained and discussed, based on the whole set of 468 three-component accelerometric records.
