The Shahrud fault in western Alborz is considered as a south-dipping reverse fault extended between the longitudes of 49.5 to 50.5°E and latitudes of 36.25 to 37°N. The northwestern end of the Shahrud fault zone overlaps the southeastern termination of the left-lateral Rudbar fault zone through an offset of 10 km. There is no evidence of historical seismicity along the fault, while records of instrumental seismicity are significant within the Shahrud and Rudbar faults relay zone. Since September 2015, the Deylaman temporary local seismic network has been installed over the area by the Institute of Advanced Studies for Basic Sciences (IASBS - Zanjan) investigating the pattern and kinematics of seismicity of the area in relation with major geological structures like the Shahrud fault. During this period of time, no important seismic activity was directly observed along the fault to reveal its active kinematics. According to our seismological and active tectonic results, the traditional definition and geographic extension of the “Shahrud thrust” is geologically unreliable. The Shahrud fault zone is, in fact, a complex structural assemblage produced by both kinematic and structural interactions of two distinct NNE-striking dextral and NW-striking sinistral fault trends at the southern flank of the Shahrud Valley.