In this paper, the Damghan Fault System is introduced based on findings of detailed structural and morphotectonic studies and a comparison of neotectonics patterns within its various parts. This fault system on the southern margin of eastern Alborz comprises four segments including Dehmolla-Siahkuh, Siahkuh- Rudbar, Rudbar-Fooladmahalleh and Labrud-Shotorgardan. The Dehmolla-Siahkuh segments is a strike slip normal fault, while the mechanism of all the others is sinistral reverse. This system is one of the important tectonic elements within the left lateral transpression shear zone with a N60E trend which, in this paper, is being reported as the Astaneh-Attary transpression shear zone. The Astaneh and Attary faults forms its northern and southern boundaries respectively. The Dehmolla- Siahkuh and Siahkuh-Rudbar segments with distinct activity in the Quaternary form a clockwise rotational fault, which is separated from the Rudbar-Fooladmahalleh segment by the Labrud- Shotorgardan segment. The rotational part of the Dehmolla-Rudbar is a transfer fault for the Labrud-Shotorgardan tear fault.
     The Labrud-Shotorgardan segment has neither a structural relation nor a similar behavior in the development of sedimentary basin with the Attary fault in the Jam region. Although the area contained within the Astaneh-Attary left lateral shear zone was clearly active in the Quaternary and this activity has left clear evidences in the Dehmolla-Siahkuh, the Siahkuh-Labrud and the Labrud- Shotorgardan segments but its Quaternary activity in the western part (Rudbar-Fooladmahalleh segment), has mainly indicated a sinistral mechanism along the Astaneh fault.
      Young geological kinematic evidences for the existence of a left lateral transpression shear zone in this part of eastern Alborz, supports the dynamic findings resulting from analysis of earthquake focal mechanism and surface deformation of historical and instrumental earthquakes as well as the results of satellite studies conducted on the lithospheric plates. All these evidences confirm the application of a compressional oblique stress on the Astaeh-Attary region in a north-northeast direction which could mobilize the Damghan fault system according to the proposed model.