OICC Press Iranian Journal of Earth Sciences 2228-785X 14 2 2021 08 05 The pattern and kinematics of deep deformation of 2012 Ahar-Varzaghan earthquake doublet (MW 6.4 and 6.2), a New seismotectonic interpretation 112 130 10.30495/ijes.2021.685393 EN Mahnaz Nedaei Geology Department, Faculty of Basic Science, Payame Noor University (PNU), 19395-4697 Tehran, Iran|Board of Directors of Geological Society of Iran Hasan Alizadeh Geology Department, Faculty of Basic Science, Payame Noor University (PNU), 19395-4697 Tehran, Iran Mahdi Jahangiri Kavian Silise Kansar Co., Khoramdareh, Zanjan, Iran Journal Article 2021 08 05 The 11th August 2012 Ahar-Varzaghan earthquake doublet Mw 6.4 and 6.2 occurred near the city of Ahar, northwest Iran, in a region where there was no major mapped fault or any well-documented historical seismicity. To investigate the active tectonics and the state of pre and post-seismic stress distribution of the source region, we applied a combination of Coulomb stress change, b-value mapping, and the Fry method. Inferred Coulomb stress field reveals the E–W-striking (dextral) fault responsible for the first event and the NNE–SSW-striking (sinistral reverse) fault for the second event. The high slip stress-released regions in the obtained b-value map and the dominant anisotropies of aftershocks on regional stress-parallel cross-sections achieved by the Fry method, together with the distribution of aftershocks mechanisms, merely highlight the particular wedge-shaped structures namely the rhombic structures. The clockwise block rotation about the vertical axis under the right-lateral regional shear between the Kura basin to the north and the Central Iranian Block to the south and NW-oriented coeval shortening leads to the formation of rhombic structures. The results of this study improve our understanding of the kinematics of active deformation in NW Iran and have important implications for seismic hazard assessment of the region and potential future failure area.