Set up a parenting contract with your teen and have some stop-in or drive-by checks done by relatives and the authorities. Talk with your teen. Let them know all of the things you have put into place in order to keep them safe and responsible.
The problem is that your teen may think, "How are my parents going to find out?" If you answer that question with, "We have people checking up on you and our home." Then your teen will be less likely to have a party.
Teens Home Alone FAQ: