MONTECITO, Calif. — Anxious family members awaited word on loved ones Wednesday as rescue crews searched grimy debris and ruins for more than a dozen people missing after mudslides in Southern California destroyed an estimated 100 houses, swept cars to the beach and left at least 17 victims dead. “It’s just waiting and not knowing, and the more I haven’t heard from them — we have to find them,” said Kelly Weimer, whose elderly parents’ home was wrecked by the torrent of mud, trees and boulders that flowed down a fire-scarred mountain and slammed into the coastal town of Montecito in Santa Barbara County early Tuesday. The drenching storm that triggered the disaster gave way to sunny skies, as hundreds of searchers carefully combed a messy landscape strewn with hazards. “We’ve gotten multiple reports of rescuers falling through manholes that were covered with mud, swimming pools that were covered up with mud,” said Anthony Buzzerio, a Los Angeles County fire battalion chief.