ABSTRACT
The landslide wrecked many residences, and many more bank accounts. Of the 69 residences involved in existing or potential sliding, 21 were entirely destroyed, and many more threatened, pending subsurface investigation and implementation of corrective measures. The Bluebird Canyon Landslide occurred in a hillside residential district on a dip slope of the ridge between Rimrock Canyon and Bluebird Canyon. Geologic field mapping and surface measurements have defined the boundaries of the October 2, 1978, landslide, permitting an estimation of its three-dimensional geometry. The landslide occurred within the Topanga Formation of interbedded siltstone and sandstone. The landslide appears to lie within a synclinal structure. Deterioration of an ancient landslide to the threshold of reactivation commonly proceeds as miniscule cumulative change. The preliminary investigation has resulted in three major types of evidence of older landslide episodes: aerial photographic studies, identification of older landslide materials, and mapping of old surfaces of rupture.
