A recent large landslide that killed more than 30 people in Washington has renewed national focus on such hazards. Mike Lynch updates us on landslides in Ky.
Matt Crawford of the Kentucky Geological Survey has been using a landslide site in Boyd County as a research laboratory since 2012. A slide there badly damaged a home that was only four years old, forcing the owner and his family to abandon it.
Six holes were drilled at the site, and automated instruments were set up, to help Crawford monitor further movement of the soil, and keep track of rainfall and ground water—which can trigger landslides.
For several years, Crawford has been gathering information on Kentucky landslides and visiting dozens of sites, including a Carroll County hillside where a large slide recently destroyed an unoccupied house and blocked a road. With contributions from local and state agencies, he has built a database of 3,000 landslides around Kentucky.
The Washington state incident showed the power of large slides to destroy structures and take lives. …Can a slide of that magnitude happen in Kentucky?
"That thing was massive...a massive amount of material, and to completely bury a community is probably unlikely here. However, the same mechanisms and triggers that caused that slide, the underlying geology there, the fact that it was a slope that had failed before, those are all things we see here."
Kentucky’s extensive road network crosses multiple geologic units that are susceptible to landslides and rockfalls. So another KGS researcher, Bethany Overfield, has analyzed almost a decade’s worth of road-repair costs related to such events provided by the state’s Transportation Cabinet:
"I essentially intersected cost data with mapped units. So I could associate costs with specific specific geologic units."
The damages are more extensive, and expensive than you might think.
"From 2002 through 2009 the repair costs totaled over 37 million dollars. It does not include pavement costs, so these costs are actually greater than what we actually see on paper."
Not surprisingly, the varying topography and the type of geologic formations in eastern and northern Kentucky—especially shale—provide conditions for the highest road-repair costs.
Overfield hopes her analysis will help the Transportation Cabinet recognize where roads are more likely to be damaged by landslides and rockfalls and budget needed repair funds.
It might seem that, once a landslide happens, it’s too late to worry about damages there. But, as these geologists will tell you, the occurrence of a landslide is one of the best indicators that it can happen again—at the same site or nearby.
That’s why visiting sites like the one in Boyd County and monitoring damages across the state are important for understanding landslides and rockfalls in Kentucky.