Just watched a portion of Victory at Sea that showed some depth charge attacks by US destroyers in the Atlantic. The overall size/scale of the explosions you show above seems about right for the DCs set on very shallow depths (maybe first run over a sub that was just spotted on the surface or at periscope depth). However, it's hard to tell from your post but if that's only one DC going off then there seem to be too many repeating gysers. Basically, it looked like there was only one big water eruption per DC. The subsequent runs (with deeper settings) didn't produce anywhere near this large an effect - basically just a low, roiling swelling up without the real high gyser effect. I've never really watched a DC attack in external view in SH4, so I'm not sure if this depth effect is modeled in the game or not.
Shallow:
Deep:
