Description: The Susceptibility to Deep-Seated Landslides map covers the entire state of California and was originally published in May of 2011 as CGS Map Sheet 58. It made use of several data layers of varying scales and formats, such as Landslide Inventory, Geology, Rock Strength, and Slope. For the statewide analysis of landslide susceptibility, the methodology of Wilson and Keefer (1985) was used in combining the rock strength and slope data layers as implemented by Ponti, el al. (2008) to create classes of landslide susceptibility (0 to 10, low to high). These classes express the generalization that on very low slopes, landslide susceptibility is low even in weak materials, and that landslide susceptibility increases with slope and in weak rocks. The landslide susceptibility matrix, based on Rock Strength (RS) and Slope Steepness (SS) in degrees, is described below:RS(1) & SS(<3 to 10); RS(2) & SS(<3); RS(3) & SS(<3) = susceptibility 0. RS(1) & SS(10 to15) = susceptibility class 3RS(2) & SS(3 to10) = susceptibility class 5RS(1) & SS(15 to 20) – susceptibility class 6RS(1) & SS(20 to 30); RS(3) & SS(3 to 10) = susceptibility class 7RS(1) & SS(30 to >40); RS(2) & SS(10 to 15) = susceptibility class 8RS(2) & SS(15 to >40); RS(3) & SS(10 to 15) = susceptibility class 9RS(3) & SS(15 to >40) = susceptibility class 10