Surficial Failures in Santa Clarita, California, during the 2005 El Nino Storms

The 2005 El Nino weather phenomenon caused intense rainfall in Southern California that resulted in floods and numerous slope failures. In northern Los Angeles County, surficial failures originating in natural slopes resulted in debris flows that affected many residential properties in the town of Santa Clarita. Because surficial failures are shallow, that is, 2-4 ft (60-120 cm) deep, generally the debris they generate are individually small. However, when surficial failures are clustered and numerous, they tend to affect large surface areas and they generate considerable volumes of slide debris. This paper describes the characteristics of surficial failures that occurred on slopes in Santa Clarita, California, discusses methods of analyses, common testing practices by local consultants, and analysis requirements from controlling agencies.