The megacity of Tehran, the capital of Iran, is subjected to a high earthquake risk. Located at the central part of the Alpine–Himalayan seismic belt, Tehran is surrounded by several active faults that show some M7+ historical earthquake records. The high seismic hazard in combination with a dense population distribution and several vulnerability factors mean Tehran is one of the top 20 worldwide megacities at a high earthquake risk. This article aims to prepare an assessment of the present-day earthquake risk in Tehran. First, the earthquake risk components including hazard, exposure, and vulnerability are evaluated based on some accessible GIS-based datasets (e.g., seismicity, geology, active faults, population distribution, land use, urban fabric, buildings’ height and occupancy, structure types, and ages, as well as the vicinity to some critical infrastructures). Then, earthquake hazard maps in terms of PGA are prepared using a probabilistic approach as well as a surface rupture width map. Exposure and vulnerability maps are also provided deterministically in terms of population density and hybrid physical vulnerability, respectively. Finally, all these components are combined in a spatial framework and an earthquake risk map is provided for Tehran.

We investigate the geodetic data set of Interferometric Synthetic Aperture Radar (InSAR) including Advanced Land Observation Satellite (ALOS)‐2 and Sentinel‐1A/1B satellites for inferring the fault model of the 2017 $Mw$ 7.3 Sarpol Zahab, Iran, earthquake. The InSAR deformation fields show that the seismogenic fault does not reach the ground surface, but some shallow folds have been triggered by the mainshock. Our preferred faulting model suggests that the coseismic rupture occurs on a single planar fault surface with a strike angle of 337.5°. Two significant slip sources are determined by the geodetic data: one is located within the 11.8‐ to 13.5‐km depth range with a peak slip of 4.9 m, and the other occurs at the shallower depth (10.5–12.5 km) with a peak slip of 4.5 m. Both of them are responsible for the primary deformation signals in the geodetic imagery. The significant fault slip concentrates at the 10‐ to 14‐km depth within the Pan‐African basement. However, most of the aftershocks have depths between 3 and 12 km in the shallow sedimentary section. We hypothesize that the Hormuz Salt section with a depth of 12–13 km detaches the high‐slip zones from the aftershock cluster, by which the fault slip is not transferred through the intervening salt section to the surface. The predicted static Coulomb stress change by our preferred faulting model at a depth of 10 km could encourage the occurrence of aftershocks. Moreover, the triggered fault‐related folding in the southwest of the seismic zone has a positive Coulomb stress change and aseismic slip caused by the mainshock.