Mudslide — Ronnie Dauber

Mudslide is the first of five books in the Misadventures of Sarah Davies, and it's where the team of teens bond together and become the main characters of the series.
Sarah Davies and her cousin Meagan set out on a grade 12 class trip along the Snake River in Idaho for a three-day hiking trip. The horrifying dream she had the night before is soon put aside as she realizes that she is teamed with the football icon who she has secretly admired all year. But things are not what they seem, and soon the fun trip turns to a horrific nightmare when team conflicts and unexpected storms trap Sarah's team in the direct path of a deadly mudslide. She is buried in mud and when she finds Meagan they team with Ali and Brad to find the missing classmates who fell victim to the rampage of the mudslide. This action-packed adventure becomes a fast-paced race against time as Sarah has to overcome conflicts and her own fears to survive the storms that lie ahead.