Why do some nuclear detonations leave craters, and others don’t?

Question

Hiroshima and Nagasaki didn’t, but other detonations did, like Castle Bravo.

In: Chemistry

Answer 1

The Castle Bravo detonation was both 1. orders of magnitude stronger than the Hiroshima and Nagasaki bombings and 2. took place *on the ground*. Little Boy and Fat Man were detonated about 500m above ground level.