Journal of Seismology and Earthquake Engineering
Volume:8 Issue: 1, Spring 2006

Active faulting in Iran is a direct indicator of active crustal deformation due to the convergence between Arabia and Eurasia which occurs at 2.1-2.5 cm/yr. In this paper active faults of Iran have been considered in some detail. Geometric characteristics, mechanisms and the trend of active fault zones in different areas of Iran have been discussed while considering their tectonic differences. Active faults in Zagros are blind and the focal mechanism solutions of the earthquakes of the region point to the presence of both thrust and transverse strikeslip faulting in its basement. Whereas in the rest of the country most active faults reach the surface. The earthquake mechanism solutions along active fault systems in eastern and central Iran imply dominance of strike-slip faulting in a transpression regime. Conversely, active faults in NW Iran are transtensive. The Alborz and Kopeh-Dagh fault zones are relatively vast active fault zones in which location of individual active faults is difficult. Aside from raised terraces in the shores of the Oman Sea, information on active faults in the Makran region is scarce.

Oblique plate convergence in collision zones may lead to complex regional strain partitioning because inherited crustal faults have various orientations with respect to the orogenic belt and the convergence vector. Combined field structural and geomorphic investigations and SPOT image analysis document the kinematic framework enhancing transfer of strike-slip partitioned right-lateral motion from along the backstop to the interior of the Zagros foldand- thrust belt in a context of active, high-angle right-oblique plate convergence. Transfer occurs by slip on the N-trending right-lateral Kazerun fault system that connects to the termination of the Main Recent Fault, a major NW-trending dextral fault partitioning oblique convergence at the rear of the belt. The Kazerun Fault system consists in three N-trending fault zones ended by bent, orogen-parallel splay thrust faults allowing slip from along the Main Recent Fault to become distributed by transfer to longitudinal thrust faults and folds.

The influence of the in-plane flexibility of floor systems on the seismic response of the structures may become significant, particularly when considerable floor slab cracking and yielding is expected. Since in recent years the composite floor systems (steel beams with upper concrete slab) have been used widely in the steel buildings, the investigation of the diaphragm behavior of composite floor systems subjected to lateral loads, is inevitable. As a part of a comprehensive study of the effective parameters in the diaphragm behavior and in-plane characteristics of the composite floor systems, two half-scale single story building models with the parameter of the direction of the joists were tested. The scale-model structures were steel buildings with composite floor system consisting of four square panels supported by side frames with X bracing. The structures were designed under the seismic load specified in the seismic code of Iran, but to ascertain the inelastic behavior of the diaphragm, the stiffness of the lateral load resisting system of the structures were increased by doubling the number of bracings, then the cyclic lateral load was applied to the structures up to failure. The paper reports on the results of the test program performed at the structural engineering laboratory of Building and Housing Research Center of Iran (BHRC). The results show that the composite diaphragms present good performance under lateral loads; however the diaphragms'' in-plane characteristics such as stiffness, ultimate strength, stiffness degradation and the crack pattern of the floor slabs are affected significantly by the relative direction of the floor joists to the lateral load (perpendicular or parallel).

Damage prediction of buried pipeline under earthquake environments is the first stage for the seismic risk analysis. In this paper, we use a Knowledge Discovery in Database (KDD) method for the pipeline damage prediction even though many studies have been performed so far with the aid of empirical, statistical, and/or theoretical methods. By employing the KDD method, much higher accurate damage prediction could be done for better understanding of pipeline damage distribution. Related factors were analyzed by a GIS based model of the Kobe water buried pipelines in the 1995 Kobe Earthquake, and a decision tree of pipeline damage classification was developed based on the Classification and Regression Tree (CART) method. A verification of the method was focused to the modeled area, and accuracy of the proposed prediction method was confirmed in comparison with an actual damage as well as predicted ones by commonly used formula of damage estimation. Results of the developed KDD model showed that the model could predict correctly the number of damage in pipeline network. The proposed method by KDD turned out the distribution of damage better than other damage estimation methods.