On August 21, 2022, the Western Australian town of Cadoux experienced a magnitude 4.4 earthquake. According to the report of the incident, that earthquake might be an aftershock of a magnitude 6.1 earthquake the town experienced 43 years earlier, in June 1979.
According to Geoscience Australia,
it was quite common for aftershocks to be experienced decades later, and this most recent tremor could have been an aftershock from the 6.1-magnitude event more than 40 years ago.
If such delays in the occurrence of aftershocks are quite common what is regarded as being the longest interval between the main quake and aftershock? Secondly, what is the reason for such delays?