Lyon County, Kentucky

GEOLOGIC HAZARDS

Many concealed and exposed faults are located throughout Lyon County. Currently, there is no evidence that these faults are active. Because of the proximity of Lyon County to the New Madrid Seismic Zone, however, strong earthquake activity is a possibility. Soil creep, slumps, and landslides along steep slopes may occur from erosion or ground motion associated with a strong earthquake.

Areas associated with saturated alluvium (unit 1) and other unconsolidated deposits (units 2 and 3) are subject to liquefaction during a strong earthquake. Alluvium deposits are also subject to flooding. Soils derived from alluvium deposits have a moderate to high shrink-swell capacity, which may affect structural foundations and roads. Flood information is available from the Kentucky Division of Water, Flood Plain Management Branch, www.water.ky.gov/floods/.

Sinkholes are common in Lyon County. Generally, sinkholes begin as small depressions like the one pictured above, which is about 3 feet in diameter. While planting or harvesting at the Western Kentucky Correctional Complex, tractors often run over these depressions, which then collapse, causing the tractor to become stuck. Photo by Glynn Beck, Kentucky Geological Survey.

Sinkholes and soil erosion are two major issues to consider in land-use planning in Lyon County. Both are encountered at the Lee Jones Lyon County Recreational Park. The above baseball field is being moved because of the formation of a small sinkhole in the old infield (top right center). Also, soil erosion is occurring along rocked drainages (foreground). Photo by Glynn Beck, Kentucky Geological Survey.

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U.S. Army Corps of Engineers bank stabilization project along the Cumberland River in Lyon and Livingston Counties. Photo by Glynn Beck, Kentucky Geological Survey.

EARTHQUAKE HAZARDS

Peak ground acceleration at the top of rock that will probably occur in the next 500 years in Kentucky

Although we do not know when and where the next major earthquake will occur, we do know that an earthquake will cause damage. Damage severity depends on many factors, such as earthquake magnitude, the distance from the epicenter, and local geology. Information on earthquake effects is obtained by monitoring earthquakes and performing research. Such information is vital for earthquake hazard mitigation and risk reduction.

The most important information for seismic-hazard mitigation and risk reduction is ground-motion hazard. One way of predicting ground-motion hazard is by determining the peak ground acceleration (PGA) that may occur in a particular timeframe. The map above shows the PGA at the top of bedrock that will likely occur within the next 500 years in Kentucky (Street and others, 1996). It shows, as expected, that PGA would be greatest in far western Kentucky near the New Madrid Seismic Zone. Ground-motion hazard maps for the central United States and other areas are available from the U.S. Geological Survey. These maps are used to set general policies on mitigating damage. For example, maps produced by the USGS in 1996 were used to determine seismic design in building codes. For additional information pertaining to earthquake hazards visit the Kentucky Geological Survey website at www.uky.edu/KGS/geologichazards/geologichazards.html.

GROUNDWATER

Wells in the Ohio River alluvium yield several hundred gallons per minute; compound horizontal wells have a potential yield as high as 5,000 gallons per minute. In most of Livingston County, drilled wells in the uplands are adequate for a domestic supply. Yields as high as 50 gallons per minute have been reported from wells penetrating large solution channels or fault zones. In the low-lying areas along the Cumberland and Tennessee Rivers and the tributaries to the Ohio River, most wells are inadequate for domestic use, unless the well intercepts a major solution opening in the limestone, and then the yield could be very large. In the uplands of the southern section of the county, between the Tennessee and Cumberland Rivers, most wells in gravel do not yield enough water for a domestic supply. Springs with flows ranging from a few gallons per minute to 177 gallons per minute are found in the county. Minimum flow generally occurs in early fall; maximum flows in late winter. For more information on groundwater in the county, see Carey and Stickney (2001).

Barnett Spring is a karst spring, which flows year around. Karst springs are common throughout Lyon County. Photo by Glynn Beck, Kentucky Geological Survey.

Land and Water

An example of the gently rolling topography in Lyon County, which is excellent for row crop agriculture. Other parts of Lyon County may have steep slopes with narrow valleys. Photo by Glynn Beck, Kentucky Geological Survey.

Kuttawa Marina is one of three marinas on Barkley Lake in Lyon County. The other two marinas are the Eddy Creek Marina and the Buzzard Rock Marina. Photo by Glynn Beck, Kentucky Geological Survey.