Operation Blackout is a Pan Pacific Defense Corps emergency protocol. In the event that the Kaiju are able to overwhelm an area, the PPDC are authorized to declare it lost, and begin an emergency evacuation to designated cities before isolating the compromised location.
When "Operation Blackout" is enacted, a five-day period allows for civilians to head to the nearest city and evacuate. After the five-day period is over, anything of value is either destroyed or evacuated. Bases are to be dug in and deactivated.