Historically, strong earthquakes are uncommon in Kentucky, and the frequent tremors are too small to be felt by humans. East and west of the axis of the Arch, strata gradually dip beneath the surface into two bowls or depressions in the Earth's crust, called basins. Rough Creek graben, that was active as early as latest Precambrian or earliest Cambrian time and that has The area is considered to have a low seismic hazard relative to other parts of the United States. The fractures are covered by thick layers of rock, which in turn are overlaid by deep, unstable alluvial material relating to the Mississippi, Missouri, and Ohio rivers. The Appalachian basin in Kentucky contains several major structural features: the Kentucky River and beyond the surface faults shown on the map (sheets 2 and 3), as a concealed system that extends into West (photo by Edward Nuhfer). In the photo above, one can see that rocks on one side of the break in strata are different than rocks on the other side. Magnitude 5.2. Remedies vary from mere maintenance that keeps drainage away from the house to expensive reconstruction of foundations. Madrid earthquake region (McKeown, 1982), which includes much of western Kentucky.