Landslides are geological disturbances of land that can occur in time periods ranging from weeks to a year.
The impact of landslides to our region is nothing new, it is estimated in Allegheny county spent $3 million in public money, and 650,025 in private funds in 2001 and 2002. From February to April 2018 alone it is estimated that in western Pennsylvania $22 million dollars of damages were inflicted, provoking govern Tom Wolfe to sign a Proclamation of Disaster Emergency.
There are many factors that can contribute to the probability of a landslide occurring. In our county we are at an increased risk for landslides due to the geology of western Pennsylvania and weather patterns. One geological factor that adds to the number of landslides is the prevalence of red beds, soft clay like soil that is often sandwiched between harder layer of sediment and prone to movement when over saturated. Quick, heavy rains accompanied by the rapid freezing and thawing of this water trapped in between rock layers also contributes to the sudden destabilization of slopes and hillslide. While some measures can be made to map landslide risk areas, landslides are fundamentally unpredictable. However, this does not imply that they are unpreventable. A comprehensive study done by the USGS on landslides in 1975 estimated that approximately 90% of all landslides in allegheny county were human made or induced. By this it is meant that some interference with the natural land structure cause destabilization that many times rain or snow patterns exacerbate, ultimately leading to a slide.
It is important as a home or business owner to know where you fall on a landslide risk map, so that you can be informed before making any land modifications to your property. As it stands, all responsibility for a landslide happening on private property is the property owners expense alone, even when a landslide results in hundreds of thousands in damages. However, when landslide affect public property, such as when they spill onto public roads, the state and county often have to spend exorbitant amounts to repair the damages, as we have seen this year. Understanding where landslides are most likely to impact private infrastructure could help prevent state and individual spending on landslides significantly. Take the first steps to understand what risk you have, and what preventative measures you can take to prevent landslides.