As I posted in another thread on bomb damage, this is a crater from a 550-lb bomb dropped from a Stuka attacking an armored train; the scale of the crater can be estimated from the track guage and the people standing to the left of the train:
(http://mailer.fsu.edu/~akirk/tanks/pol/PolishArmoredTrain.jpg)
The US Air Force had standard approximations for crater size depending on bomb weight:
Bomb Weight Crater Diameter
250-lb GP 10 feet
500-lb GP 15 feet
1000-lb GP 35 feet
2000-lb GP 50 feet
The depth of a crater is approximately half its diameter; this approximation holds all the way up to large nuclear detonations.