JOINT-INDUCED LANDSLIDE SUSCEPTIBILITY IN THE SOUTH AND CENTRAL APPALACHIAN MOUNTAINS, EASTERN US

Landslide susceptibility models typically account for (a) slope angle, (b) regional precipitation, (c) natural and anthropogenic landscape modification, and (d) lithology. Recent, field-based investigations of large, rock-block slides in northeast Alabama identify slides in areas where slopes are parallel to regional joint patterns. To investigate the potential for increased landslide susceptibility, we identify zones where slopes parallel regional joints in the southern Appalachian Mountains using joint measurements from the Valley and Ridge and western Blue Ridge (N=57; n=3,051) covering parts of Alabama, Georgia, Tennessee, and Virginia. Using these joint measurements, available LiDAR data, and published geologic maps, a predictive model is developed for identifying high-risk areas susceptible to joint-controlled landslides. High-risk areas are defined as areas where joint orientation and the strike of the slopes approach a subparallel trend (< 10° difference). Using this approach, seven high-risk areas within northeastern Alabama (N=3), Georgia (N=1), Tennessee (N=2), and southwestern Virginia (N=1) were identified for further evaluation. Surficial investigation of high-risk areas using LiDAR based DEM’s, geologic maps, and field reconnaissance indicates the presence of mass wasting features in northeastern Alabama along ridges with an orientation of ~ 070-250°. Within southwestern Virginia, ridges orientated ~ 065-245°, contain a previously unidentified slump and a previously mapped landslide. The presence of mass wasting features in 3 of 7 areas defined as high-risk for joint-related slope failure suggests the predictive model approach presented here is effective at identifying joint-controlled landslide risks and that joint orientations is an important factor for mass wasting in the southeastern U.S.