U. S. Geological Survey

 A Comparative Analysis of Hazard Models for Predicting Debris Flows in Madison County, Virginia


Meghan M. Morrissey, Gerald F. Wieczorek, and Benjamin A. Morgan
Open-File Report 01-0067


Figure 1.  Diagram illustrating the parameters involved in the factor of safety equation (Eqns. 1 and 4).  Tree root-soil system is located above the failure plane (D denotes depth to failure plane) where qo is tree surcharge, Cr , Cs are root and soil cohesion, and a is slope angle.  (From Hammond et al., 1992)