A deadly N.C. landslide? History warns us to prepare

From Brad Johnson, Assistant Professor of Environmental Studies at Davidson College:

The tragic landslide last week in Washington State has taken many lives and has highlighted the dangerous slopes that lie above many houses and mountainous areas. Perhaps the most disturbing news to come from the event was the fact that the geologists in the area knew that the slope was unstable and had recorded landslides on the hill slope in 1949, 1951, 1967, 1988, and 2006. Nonetheless, the county had permitted new construction in the area, and many new residents knew nothing of the possibility of a landslide above their house.

We find ourselves in a similar position here in North Carolina, since much of the Blue Ridge area is susceptible to landslides and the population of the area continues to grow into more mountainous areas. In 2004, heavy rainfall associated with the remnants of Hurricanes Frances and Ivan caused at least 400 landslides in western North Carolina. One of these, the Peeks Creek Landslide, killed 5 people and destroyed 15 homes.

Similar hurricane rainfall in 1940 caused over 2,000 landslides in the Watauga area and killed 14 people. Many of the people killed in these storms lived in houses built on landslide debris, a clear indication that future landslides are probable if not certain. Few of these people knew their situation as dangerous. This trend continues, with at least 136 structures built so far on the locations of 1940 landslides.

In 2005, the state legislature identified the problem and created a statewide landslide hazard mapping team tasked with identifying the locations of past landslides and mapping paths of potential future landslides. The team began mapping each county in western North Carolina one by one.

Despite the landslide hazard team's insistence that it was not a regulatory body and that the information was only for public knowledge, developers and builders pushed back fearing that knowledge of slope hazards would be bad for mountainside property sales.

The program was among the first budget cuts in 2011, despite the fact that the program only cost the state $500,000 per year. The program had only finished mapping landslide hazards in four of the 26 mountain counties on North Carolina. As a result, population and construction grows in western North Carolina in areas that have recorded landslides in the past 100 years. Few, if any, people are aware of the danger created by the slopes above or under their house.

The remnants of hurricanes pass through the North Carolina mountains regularly and it is simply a matter of time before the next set of landslides. A statewide landslide hazard mapping team is critical to identifying hazardous areas and providing that information to the public in order to reduce the loss of life in future landslides.