A large inventory of landslides exists for Allegheny County, Pa., and historical movement of manyof these has resulted in considerable damage to property, roads, and infrastructure. Along InterstateRoute 79, a subset of the landslide inventory includes deep-seated rockslides, two of which reactivatedduring construction of the highway in the late 1960s (Gray and others, 2011). Following the initialmovement of the rockslides, slope-stability investigations were conducted (Hamel, 1969; Hamel andFlint, 1969), and measures were taken to reduce their impacts to the highway, but movement of at leastone of the rockslides persists even today. Long-term continuous monitoring of such landslides providescritical data used to assess how the state of activity and velocity of movement (when the landslide isactive) change with rainfall and snowmelt. Currently, we are continuously monitoring meteorologicalconditions and movement of a rockslide along the northbound side of Interstate Route 79 in Aleppo, Pa.(Figure 1). The project is intended to extend over many years (approximately 5 to 10) in order to collectsufficient data to assess how extreme storms, prolonged wet periods, and melting of the snowpack affectthe landslide. The rockslide is an ideal location for such long-term monitoring because the land is ownedby the Pennsylvania Department of Transportation (PennDOT), and movement is not directly impactingthe highway; therefore no stabilization measures are necessary in the short term.
