This study presents the results of a detailed structural analysis of the west-central Alborz with emphasis on the pattern of neotectonic stress field on the Manjil-Rudbar fault This part of the Alborz mountain is characterized by an abrupt change of structural trend from NW-SW to N-S in Talesh mountain. in order to determine th geometry and mechanism of faults around The Manjil-Rudbar-Earthqake-fault are fault planes and related striations in 28 stations measured. By inversion of these data, stress directions and associated tectonic regime for each station hsd been determined.
Inferring principal stress direction (s1) from the geological indicators (inversion of the fault slip data) and the focal mechanisms (p-axis), a map of stress orientation around the Manjil-rudbar fault is proposed. The stress direction shows in vicinity of the fault an E-W directed stress that lies nearly parallel to the strike of itA way from the fault the stress direction becomes parallel to the regional stress direction namely NE-directed. Fault-parallel stress direction near the fault suggests an effect of the extremely high shear strength resulted from the N-S-directed convergent of the Iranian plate toward the rigid Caspian block. The tectonic regime deduced by version of fault slip data shows two distinct behaviors:in vicinity of the fault it shows a strike-slip regime, which results from compressive regime away from it.