| The stability of the Mission Peak Landslide head scarp is controlled by at least four pervasive discontinuities. Kinematic analyses of these discontinuities supported field evidence for: (1) flexural toppling along (J2: 76/110), (2) single plane sliding on (J4: 42/260), and (3) wedge failures incorporating sets sub parallel to (J1: 60/196). Block Theory was applied to the retrogressive block failures along the head scarp boundaries to identify the most unstable block geometry (key blocks) intersecting the scarp face. Predicted key block geometry was inconsistent with corresponding block molds in the scarp face. This was attributed to statistical orientation error, and inconsistencies in joint spacing.; Head block deformation and total rock debris runout distance were numerically modeled using Discontinuous Deformation Analysis (DDA). Pseudostatic analyses showed complex modes of failure correlative to field observations. Total rock debris runout distances were comparable to results computed from the energy-line method, though unreliable due to numerical creep and inconsistent kinematics under dynamic conditions. |
