Abstract

Landslides are a persistent threat to mountainous communities and a frequent occurrence here in western North Carolina (WNC) due to steep slopes and heavy rainfall. The orientation of weaknesses in the rocks, such as foliations and fractures, can also contribute to landslide frequency. Thus, structural patterns and geomorphological processes need to be understood in order to mitigate these natural hazards. Recent field and geophysical research has suggested that Cenozoic uplift of the southern Appalachian mountains resulted in networks of fracture systems across WNC, called lineaments, that can increase the risk of landslide hazards. Slope failure assessments have been completed in many surrounding counties by the North Carolina Geological Survey (NCGS), with examples of slope failure attributed to lineament fractures. One of the lineaments, the Laurel Creek Lineament, is exposed through the town of Spruce Pine, NC. Fractures associated with this lineament are abundant throughout the Spruce Pine 7.5-minute quadrangle and dominantly strike toward 260°. The target of this study was to examine concentrations of landslides in the Spruce Pine quadrangle and evaluate the role of lineament fractures in the occurrences of these landslides. 63 landslides were identified in the field and from 1-m resolution LiDAR elevation models with ArcGIS software. The aspect of landslide directionality was compared to the orientation of fractures and foliations. Landslide aspects ranged from 010° to 340°, with higher frequencies parallel to the joint fabric. ~25% of the landslides occurred on east or west facing slopes with aspects parallel to the joints. Another 43% of landslides occurred at aspects that could indicate block failure along foliations or wedge failure between the foliations and joint fractures. These data indicate that lineament fractures are an important structural control on slope stability in this quadrangle.

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