godzilla 2014 what i was thinking

Area 51 

Or godzilla has been taking a nap for 60 years...

i supose this, after attacking him with so many 'tests' in the pacific up to 63, godzilla dissapears for about 50 or 60 years then attacks the nulcear plant (if that was him) or is reawaken by the radiation from that plant which could've been attacked by the MUTO monsters, who were probably engineered by MUTO to combat godzilla should he or anouther(depending on the actual plot or the characters perspective) but i'm not sure on that, about half of the answer will be in the Godzilla: The Awakening prequel comic

Well, people are likely more in shock about how everything is crumbling around them first before noticing the giant culprit, and those who thought they saw him would likely be interrogated and notified that they experience heavy trauma from the event that caused them to believe they were seeing it.