Characterization of the 2017 mass movement episode in Snow Creek Canyon, Forest Falls, San Bernardino County, California

SMSU Event Center BC

A mass movement in Snow Creek Canyon, above the town of Forest Falls, occurred on February 17, 2017. The mass movement rapidly moved downslope and transported large boulders and trees approximately 610 m (2000 ft) down the narrow canyon. The purpose of this study was to characterize the mass movement in terms of materials in motion, moisture content, nature of movement, and rate of movement. The study analyzed historic aerial photographs, ground based imagery and videos, and photos obtained by UAV to understand the mode and velocity of movement. Sediment and rock samples from the source area were analyzed to determine rock type, mineral content, physical weathering and observe signs of historical tectonic activity. Meteorological and seismic databases were accessed to obtain timing and volume of precipitation as well as potential seismic activity before the movement occurred. Previous work that has been conducted within the study area was examined to compare and contrast the findings to the Snow Creek Canyon event. Data collected during the study confirmed the Snow Creek Canyon mass movement was a translational rockfalldebris-slide. The fractured-nature and weathering of the insitu material and the sudden and violent movement contribute to rapid breakdown into sediment that later appears to be remobilized down-canyon into debris flows