In this study, I simulate high‐frequency ground motions at five stations in the National Capital Region (NCR) of India for a large hypothetical 8.5 earthquake in the Himalayan central seismic gap, at fault‐distances of about 200–300 km. A smaller magnitude earthquake (22 July 2007 4.9 Kharsali) is used as the first‐step empirical Green’s function (EGF) for the synthesis of an intermediate‐sized earthquake of magnitude 6.8 (1991 Uttarkashi earthquake). In the second step, the records of 6.8 synthetics are further used as the EGF in the simulation of the postulated 8.5 earthquake. Because the target region for the postulated earthquake is devoid of the necessary information on the geophysical constraints, I perform a suite of simulations for plausible scenarios of fault dimensions, stress‐drop ratios, C, and scaling factor, N (between the EGF and target earthquake). This article uses heterogeneous slip distributions and variable stress drops on the rupture plane to simulate the target earthquake, based on the power spectral density of the von Karman correlation function. The estimated values of the ground‐motion intensity measure (GMIM) such as peak ground acceleration, along with the engineering parameters such as the 5% damped, pseudospectral acceleration (Sa), Arias intensity (), and significant duration (), are compared for both the recorded and the simulated time histories. The estimated GMIMs of the 6.8 synthetics are examined with those of the 1991 6.8 Uttarkashi earthquake, whereas the 8.5 simulations are compared with those predicted by prevalent ground‐motion prediction equations for rock sites. The 8.5 earthquake scenarios indicate higher GMIMs and seismic hazard in the NCR, principally due to the area being underlain by sediment layers and fluvial deposits.