In this site (published on 6 November 2001) I found the following information:
Historical data suggest there is a major earthquake in Tehran every 158 years and the last one there was in 1830.
The 1990 Manjil-Rudbar earthquake occured 160 years after the last major earthquake in Tehran, just 2 years after reaching the 158 years interval.
Can we say the 1990 earthquake postponed a major earthquake in Tehran for another century?
It's true that the fault that caused the 1990 earthquake differs from the fault that caused the 1830 one; but the epicenters are close in a geographical sense and the seismic energy of the Earth got evacuated well in the region after the 1990 earthquake.
There was alao a 5.2 magnitude earthquake near Tehran on 2017-12-20; but that can't be counted a major earthquake. The 1830 earthquake had a magnitude of 7.1.
P.S. I don't know if evacuated is a good word here.