Sorry my calculations are way out (been a while since i was at school). It is roughly equal to 900,000 1 mega ton nukes
worked out as follows google the enrgy in megaton nuke find following url
http://hypertextbook.com/facts/2000/MuhammadKaleem.shtml
energy of a 1 megaton nuke = 84 000 000 000 000 000 joules
kinetic energy = mass times distance
assuming supes moved the moon just 1 km I dunno i did not read the book
google mass of moon http://hypertextbook.com/facts/2002/AdaLi.shtml
moon mass 74 000 000 000 000 000 000 kg multiplied by distance in metres (1000) = 74 000 000 000 000 000 000 000 joules
divide the 74 000 000 .. etc by the 84 000 etc and you get 880,852,380.
anyhoo the case is worse for dc supes has only to use one billionth of his power to destroy a city. the guys a frickin nano surgeon of restraint