What kind of natural disaster happened on Tuesday in La Conchita, California?

Rescuers with listening devices sensitive enough to pick up a whimper or faint tapping searched Tuesday for victims feared buried in a mudslide that sent trees and dirt thundering onto this seaside hamlet, killing at least six people. There was hope of finding survivors because searchers were discovering spaces under the debris large enough to hold people, Ventura County Fire Chief Bob Roper said as darkness fell on the rescue effort for a second night. Authorities said around a dozen people were missing, and 10 had been injured.