A large inventory of landslides exists for Allegheny County, Pa., and historical movement of many
of these has resulted in considerable damage to property, roads, and infrastructure. Along Interstate
Route 79, a subset of the landslide inventory includes deep-seated rockslides, two of which reactivated
during construction of the highway in the late 1960s (Gray and others, 2011). Following the initial
movement of the rockslides, slope-stability investigations were conducted (Hamel, 1969; Hamel and
Flint, 1969), and measures were taken to reduce their impacts to the highway, but movement of at least
one of the rockslides persists even today. Long-term continuous monitoring of such landslides provides
critical data used to assess how the state of activity and velocity of movement (when the landslide is
active) change with rainfall and snowmelt. Currently, we are continuously monitoring meteorological
conditions 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 collect
sufficient data to assess how extreme storms, prolonged wet periods, and melting of the snowpack affect
the landslide. The rockslide is an ideal location for such long-term monitoring because the land is owned
by the Pennsylvania Department of Transportation (PennDOT), and movement is not directly impacting
the highway; therefore no stabilization measures are necessary in the short term.
