Western North Carolina Landslides
Friday, April 17, 2009
Western North Carolina Landslide Real Estate
Data compliments North Carolina Geological Survey.
Slide 106 - This is a map showing different hazards associated with the various soil types as mapped by soil scientists (digital soil survey of Macon County) which is one map NCGS will provide to the 19 declared counties of the Hurricane Recovery Act of 2005 as part of the Landslide Hazard Mapping project. A strong correlation between the locations of known slope failures (shown in yellow) and the soils shown in dark red which have been determined to be associated with landslides. Some slides do not appear to correlate with landslide prone soils for two reasons: 1. Small areas of landslide prone soils may not show up at this scale, or have not been mapped. 2. Slopes modified since the soil survey was done may fail due to modifications and not necessarily due to soil type.
In North Carolina there is a conspiracy of silence on the part of legislators, county commissioners and Realtors regarding mountain real estate. What are they hiding ?
Western North Carolina Landslide Disaster Declarations
In the past decade the following states have received major federal disaster declarations due to the combined factors of flooding, mudslides and landslides: California (4), Colorado (1), Kentucky ( 3), Ohio (2), Washington (5), Pennsylvania (1), West Virginia (10), North Carolina (2), Utah (1) and Oregon (4). Occasionally FEMA does not identify the type of disaster. For instance North Carolina received 2 declarations in September 2004, both were for flooding and landslides, yet the disasters were classified storm events.
Western North Carolina Soil Surveys
Surveys for the 23-county area known as Western North Carolina document that mountain soils are fragile, extremely water-reactive and as a result “unsuitable” or “poorly suited” for residential development. Here are some examples of soils-linked-to landslides.
Donin/McAloon Landslide 2009: Tuckasegee-Cullasaja complex (TvE) Soils
This Maggie Valley landslide illustrates the danger of building a home below an insecure, ready-to-fail slope. As is always the case, the property owners did not discover until after the fact that their home was built in a county-identified hazardous location. The Donin property loss was caused by rain on a portion of a neighbor’s upslope unstable lot.
Campbell Mountain Estates Landslide 2005: Meta-sedimentary Soils
The unregulated use of a bulldozer set off what could have been a massive slide near Maggie Valley in the Campbell Mountain Estates subdivision. Billy Brede, the developer, was able to stop the slope failure by using extraordinary measures.
County officials and geologists on the scene of the Late September Way landslide had no difficulty in determining the reason why the mountain fractured. It was an amateur's attempt to modify a crumbly, mica-laden, slope.
Mountain Air Resort- Austin View & Hemlock Bluff Villas Landslides ( 2003-2004): Colluvial soils
Engineering reports submitted in the Mountain Air Development Corporation lawsuit state that colluvial soils were contributing factors in these multi-million dollar landslides.
Western North Carolina Landslides
Western North Carolina landslide fatalities and property loss have been caused by rapid debris flows: water reacting with unstable soils. But there is another type of destructive landslide. It has various names: deep-seated landslide, ancient landslide and big slow mover. North Carolina geologists suspect that an ancient landslide was responsible for the Hunters Crossing home condemnations. It is not known how many of these dormant landslides are present in the mountainous region but it is worth considering the significant harm they have caused in other states.
Aldercrest-Banyon Landslide Kelso, Washington ( 1998-1999)
The Aldercrest-Banyon subdivision was built in the 70s over a huge inert landslide. In October 1998 the community was declared a federal disaster area after this landslide reactivated: 137 homes were condemned. The former neighborhood is now a park.
City of Dreams Landslide Oregon City, Oregon (2007)
Two years ago, the KATU news team investigated creeping land masses under homes in and around Hidden Lakes Estates. These on-the-move landslides have damaged four homes a mile away and are affecting property owners in Hidden Lakes.
Mountain Green Landslide North Salt Lake City, Utah (1998-2009)
Land under the Springhill neighborhood began shifting in 1998. Initial movement from this buried landslide scarred homes and infrastructure and then it slowed. The landslide has accelerated and now threatens the 13 remaining homes.
Regency Ridge/ Colorado Springs Landslides Colorado Springs, Colorado (1995-1999)
Geologists believe that slope modifications, sprinkler systems and heavy precipitation were responsible for more than a dozen underground landslide-reactivations throughout the city. Colorado Springs was declared a federal disaster area in 1999.
On March 19, 2009 The New York Times reported that although landslides are significant threats in numerous states and result in $3.5 billion in damages and 50 deaths yearly there is no federal data bank to track these catastrophic events. Presently the U. S. Geological Survey’s National Information Center is forced to rely on voluntary state reporting. Lynn Highland, coordinator for the Center, said that “ getting states to track landslides is “like herding cats.” She said during the interview with Scott Streater that state governments are wary of providing too much information because they believe that landslide incident reports could lead to prohibition of hazardous-land development and property devaluation.
If a federal agency finds it difficult to evaluate landslide risks the public will find it even more challenging.
What the public doesn’t know is that most landslides are set in motion by demands for hazardous-land residential permits and the complicit actions of city and county governments.
Western North Carolina mountain real estate was classified landslide-prone and highly-hazardous in 1998. Western North Carolina landslide mapping was authorized in 2000. Fifteen mountain counties were declared federal disaster areas in 2004. Since 1998 only 2 out of 23 designated at-risk counties have been mapped. This real estate risk information has never been publicized: county websites do not disclose hazardous-land conditions and Realtors remain conveniently silent.
Meanwhile members of the North Carolina General Assembly are sitting on the sidelines reading landslide fatality and property loss reports. The questions before the legislators via the reintroduced Safe Artificial Slope Construction Act are simple: should the state regulate hazardous-land development and advise prospective buyers of the substantive risks?