jerk, jolt
raid
deed
crackdown - for the That's Life! puzzlers
Crash is a 5-letter word that can refer to "a sudden noise".
The word punitive if defined simply basically means "punish". So to take sudden punitive action would be to take sudden disiplinary action essentially.
A four letter word starting with the letter a is able.
onrush
craving
Sudden
Unexpected
fervent
It depends on what you mean by 'four letter word'. Thea has four letters, so yes it is. It is not a swear word, so it's not that kind of 'four letter word'.