When I wrote Kingdom Authority, I realised that some of the spiritual powers of evil were locked up following the flood (1 Pet 318-19; 2 Pet 4-5). But I did not understand why was God able to do this after the flood, when he could not do it before the flood? The penny has now dropped.
The reason is as follows. God gave authority over the earth to humans. They had authority on earth and over the earth, but they did not have authority over the depths of the earth and the structure of the planet. God retained control of the planet itself.
When Adam rejected God, and submitted to the tempter, he placed himself under the authority of the spiritual powers of evil. They gained authority over the earth. The powers of evil had authority to be there, so provided they remained in contact with the earth, God could not touch them. If they had attacked the spiritual realms where God dwells, they would have been defeated in a minute. As long as they worked upon the earth, they were safe.
At the time of the flood, some of the spiritual powers attacked the depths of the earth and broke them up.
On that day all the fountains of the great deep were broken up (Gen 7:11).When some of the spiritual powers of evil attacked the great depths of the earth, they moved away from the place where they had authority upon the earth. God was able to send a host of angels and take them captive, so that they could not work on earth any more. God had authority to do this, because they had moved to a place where they did not have authority.