The Great Central U.S. ShakeOut is an annual opportunity to practice how to be safer during big earthquakes: “Drop, Cover and Hold On.” The ShakeOut has also been organized to encourage you, your community, your school, or your organization to review and update emergency preparedness plans and supplies, and to secure your space in order to prevent damage and injuries
In the past 25 years, scientists have learned that strong earthquakes in the central Mississippi Valley are not freak events but have occurred repeatedly in the geologic past. The area of major earthquake activity also has frequent minor shocks and is known as the New Madrid Seismic Zone. The NMSZ is made up of several thrust faults that stretch from Marked Tree, Arkansas to Cairo, Illinois.
Earthquakes in the central or eastern United States effect much larger areas than earthquakes of similar magnitude in the western United States. For example, the San Francisco, California, earthquake of 1906 (magnitude 7.8) was felt 350 miles away in the middle of Nevada, whereas the New Madrid earthquake of December 1811 rang church bells in Boston, Massachusetts, 1,000 miles away. Differences in geology east and west of the Rocky Mountains cause this strong contrast.
Geologic hazards, such as earthquakes, landslides, and sinkholes, cause millions of dollars in losses in Kentucky each year. The level and type of geologic hazards vary across the state, depending on the geology, topography, and hydrology.
A large landslide in Hickman, in western Kentucky , destroyed many houses, and more than $10 million has been spent to try to fix it. About $1 million has been spent to repair damage caused by landslides on the Audubon Parkway between Owensboro and Henderson . Fifty-five percent of the state sits atop carbonate rocks that are prone to developing karst. Karst hazards include sinkhole flooding, sudden cover collapse, and leakage around dams. The estimated damage caused by karst hazards every year in Kentucky is between $0.5 million and $1 million.
As the existing infrastructure begins to age, the expanding economy and population are forcing new development and construction in more undesirable locations, which are more prone to geologic hazards.
Kentucky is affected by earthquakes from several seismic zones in and around the state. The most important one is the New Madrid Seismic Zone, in which at least three great earthquakes, each estimated to have been greater than magnitude 8 on the Richter scale, occurred from December 1811 to February 1812. Though the state was sparsely settled, these great earthquakes affected the whole Commonwealth of Kentucky.
Some local newspaper descriptions of the earthquake:
“About half after two o’clock, yesterday morning, a severe shock of an earthquake was felt at this place: the earth vibrated two or three times in a second, which continued for several minutes, and so great was the shaking that the windows were agitated equal to what they would have been in a hard gust of wind” (Kentucky Gazette, Lexington, KY).
“On Monday morning the 16th instant, this place was visited by a most alarming Earthquake (in Louisville) We are induced to believe, the continuation was from 4 to 6 minutes, though some say it was not so long; — about an hour afterwards, another shock was felt; and a little after sunrise, a third, which broke off several chimneys, and injured some houses otherwise” (Poulson’s American Daily Advertiser, Philadelphia, PA)
An earthquake measuring 5.2 on the Richter scale occurred in 1980 near Sharpsburg in Bath County and caused an estimated $3 million in damage; 269 homes and 37 businesses in nearby Maysville were damaged. Thus, earthquakes pose high seismic hazards and risk to the Commonwealth of Kentucky.