Took me a while to get back to this thread... Each location has a different "resurgency" rate, which gets faster as later locations open up. The general formula for the resurgency rate is:
((60 - location_ID * 1.5) * 60)
So for KAF (location #2, that's:
((60 - 2 * 1.5) * 60) = 3,420 seconds, or 57 minutes for each point raise
And each subsequent location will creep up by a point 1.5 minutes faster than that. Which is not exactly true, there's some rounding in there which means sometimes the resurgency rate goes up by 1 min, sometimes 2 mins.