The typical homeowner’s insurance policy does not cover damage from earthquakes. The Coastal Plain near the Fall Line is a wedge of soft sediment forming a feather edge overlying hard basement rock, and such a circumstance focuses the destructiveness of seismic waves. The station could have withstood significantly more," The quake's epicenter was approximately 11 miles away from the plant.The Justice Department's 1977 memo, obtained by the In September, the Nuclear Regulatory Commission recommended Using new advancements in the field of passive seismic research, Blake and Nash mapped the subsurface of what is known as the Botkins and New Knoxville quadrangles, an area in the Anna Seismic Zone that covers northwestern Shelby County and small parts of Auglaize County and that includes Anna, Botkins, Kettlersville and New Knoxville. Blake and Nash note: “Geologists widely accept that in regions where thick glacial materials overlie bedrock, there is a greater risk for destructive shaking during a large earthquake.” Adding, “The behavior of seismic waves is dependent on the density of the material through which the waves travel. Bedrock has high relative density and facilitates the transfer of seismic energy efficiently with low amplification, meaning the perceived shaking is typically low. Virginia’s past seismic activity is concentrated in three primary areas: the Central Virginia seismic zone (CVSZ), the Giles County seismic zone (GCSZ), and the Eastern Tennessee seismic zone (ETSZ). The Mercalli scale is a measure of the effects of an earthquake at a particular place and depends not only on the strength (magnitude) of the quake, but also the distance from the epicenter of the quake and the local geology at the observation point. The MMS is a quantitative, logarithmic measure of energy released and each unit corresponds to a ten-fold increase in wave amplitude. Mapping is scheduled for completion in late 2016.Bollinger, G. A, 1981, The Giles County, Virginia, seismic zone — configuration and hazard assessment Bollinger, G. A., and Sibol, M. 1985, Seismicity, seismic reflection studies, gravity and geology of the central Virginia seismic zone; Part I, Seismicity: Geological Society of America Bulletin, v. 96, p.49-57.Bollinger, G. A., Snoke, J. Since 1875, more than 40 earthquakes have been cataloged in the Anna Seismic Zone in western Ohio, including the largest earthquake in Ohio’s recorded history, which took place on March 9, 1937 near the village of Anna in Shelby County. The Anna school was condemned and torn down. The company, then operating as Virginia Electric and Power Co., or Vepco, told the former Atomic Energy Commission in June 1973 that "faulting of rock at the site is neither known nor suspected," even though the company knew about the existence of faulting at North Anna, the 1977 memo said.The nuclear power station, about 90 miles southwest of the nation's capital, has been shut down since the August quake. Currently, DGMR has received a 3-year Federal Emergency Management Agency (FEMA) funded grant to identify and map faults in the seismically active regions of Virginia, including the Central Virginia and Giles County seismic zones. U.S. Department of the Interior U.S. Geological Survey Data for Quaternary faults, liquefaction features, and possible tectonic features in the Central and Eastern The reasons for this discrepancy remain uncertain, but a 2018 study by two geologists from the Ohio Department of Natural Resources, Daniel R. Blake and Andrew Nash, may shed new light on an answer. Unlike the West Coast, the East Coast is situated near the center of a tectonic plate and resides on what geologists call a passive margin. The CVSZ is located within the central Piedmont along the James River and includes the counties of Fluvanna, Goochland, Cumberland, Powhatan, Louisa, Albemarle, Buckingham, Hanover, and Chesterfield, and the cities of Richmond and Charlottesville. The GCSZ is along the New River Valley in Giles County, and extends to the southwest, and includes parts of Pulaski, Bland, Wythe, Montgomery, Grayson, and Carroll Counties. The ETSZ stretches from northern Alabama and Georgia north through eastern Tennessee and includes a small portion of far southwestern Virginia in Lee County.
This new information, along with future passive seismic measurements in the region, will help the Ohio Department of Natural Resources better understand and prepare for any future earthquakes that may occur in the Anna Seismic Zone. Further research into the geologic control of earthquakes in Virginia could greatly lessen the impact of a destructive event by 1) improved predictability and characterization of damages, and 2) delineation of earthquake-susceptible substrates in urban areas such as Richmond, as well as for situating critical emergency response facilities throughout the state. The March 9 earthquake was the stronger of two quakes that hit Anna that week.
Earthquakes from 3.5 up to 5.5 are felt but there is little structural damage; above 6.0, damage increases dramatically. The seismic activity in western Ohio around Anna is relatively frequent compared to other parts of Ohio, and hence, the area is referred to as the Anna seismic zone. The Piedmont has been assembled piece-by-piece through geologic time and is laced with numerous faults of varying ages.