I agree with Lulu. I can now discuss alcohol with my 16yr old very calmly and she feels comfortable about telling me when she has had alcohol or what her friends get up to when they drink. I think for her seeing her friends really drunk and having to look after then has put her off to a certain extent.
I would ask her what things she think could have happened out there in the bush in the worst case scenario. Also ask her who she thinks she has hurt and how, make her realise she has hurt herself too. (th youth liason officer at the police station gave me those tips)
She needs to take ownership of the situation rather than someone just telling her she is a naughty girl.
Good luck