Earthquake in Virginia! August 23, 2011, the Day the Earth Shook Near the North Anna Power Plant

An earthquake in Virginia?

Possibly up until mid-afternoon on Tuesday, August 23, 2011, earth tremors were one of Virginia's little known secrets. But an earthquake that slightly shakes President Obama's pre-Labor Day golf game almost 600 miles (about 965 kilometers) away on Martha's Vineyard, that prompts evacuation of the Pentagon, the U.S. Capitol Building, and parts of the White House in the nation's capital and the FBI Building in New York City, and that initially is rated at 5.9 magnitude?

Now that is an earthquake that definitely garners widespread attention.

Amazing visualization of energy traveling out from Virginia earthquake

Please click on the link immediately below to view a beautiful visualization of the energy traveling out from this earthquake. Seismic energy is detected by over 4,000 sensors at over 400 broadband seismic stations across the United States. This instrumentation, which was installed beginning in 2004 under the auspices of the National Science Foundation, is integral to the EarthScope Array Project, which collects detailed seismic images with the objectives of studying and controlling earthquakes. The visualization was triggered with the first spasm at 17:51:03 UTC (1:51:03 p.m. EDT) and recorded seismic energy until 18:27:31 UTC (02:27:31 p.m. EDT)

Where was I when the earth moved?

I was researching a Chesapeake Bay prehistoric marine invertebrate on the fourth-floor stacks of the Newman Library at Virginia Polytechnic Institute and State University (Virginia Tech). Suddenly, the blinds on all four windows spaced along the wall quivered and whipped out and back against the glass. The low sound of wood teetering back and forth on casters spread quickly like a domino effect through all twelve study booths and then the mini-table at which I was seated. For a minute, I thought it was the effect of researching while plugged in to the inspirational beauty of Mark Romero's "Midnight Sun."

But then to my left a young male student said, "Did you see what I just saw or did you imagine what I just imagined? The floor moved back and forth under my feet. Weird! Weird! The shelf that has the book I need just moved back and forth before my eyes. Weirder! Weirder!"

As a previous resident of Utah, I knew at that moment that it was, not the unimaginably energizing effects of Mark Romero's guitar-playing, but an earthquake.

The earthquake that shook the mid-Atlantic coast:

When: At 1:51:04 p.m. Eastern Daylight time (17:51:04 UTC), an earthquake surprised the mid-Atlantic eastern seaboard. Even more astonishingly, the epicenter of the earthquake was located in the seemingly quiet geology of the Commonwealth of Virginia.

Magnitude: Originally tying, at a rating of 5.9 magnitude, with the worst, reported Virginia earthquake, the earthquake was subsequently downgraded to 5.8 magnitude.

Where: The epicenter is situated over 100 miles (161 kilometers) northwest of Jamestown, the site of the first permanent English settlement in 1607 in the then-British colony of Virginia.

According to the U.S. Geological Survey official report, the epicenter is located at 37.936°N, 77.933°W. That location is tracked to an unnamed road in Mineral, Virginia. Major highways which demarcate the epicenter include Goodwin Store Road (State Route 677) to the west, Cuckoo Road (State Route 643) to the north, and Indian Creek Road (State Route 699) to the east.

The epicenter is located less than 10 miles (16 kilometers) west of the North Anna Nuclear Generating Station.

Mineral, Virginia: pastoral beauty of former mining town with a nuclear power plant

Mineral, Virginia, is a quaint town in the county of Louisa in east central Virginia. The town was known formerly as Tolersville after its founder, Adam Toler (November 30, 1766-March 20, 1813), a merchant and Louisa County native.

Upon incorporation in 1902, Tolersville changed its name to Mineral in recognition of local mining industries, especially gold, which benefited the community. In fact, Mineral, with over a dozen gold mines, was the center of gold mining in Louisa County. Pyrite ore was also processed there to extract sulfur for the production of sulfuric acid, an integral component in many chemical processes. Additionally, Mineral was rich in lead. Mining occupied Mineral for almost 100 years, from the opening of gold mines in 1830 until the closing of the pyrite mines in 1921.

Louisa County itself has an ideal location for businesses and residences at the center of a triangle formed by Fredericksburg to the north, Charlottesville to the west, and Richmond to the south.

As such, the Mineral area again emerged as a prime location for another industry: nuclear power plants. Virginia's second set of nuclear reactors were installed on a 1,075 acre (4.35 square kilometers) site on the shores of scenic Lake Anna, at a distance of less than 10 miles (16 kilometers) southeast of the town with its over 400 inhabitants.

North Anna Nuclear Generating Station

Formed by a dam on the southeasterly flowing North Anna River to serve as a water coolant reservoir for the power plant, Lake Anna stretches for 17 miles (27 kilometers) in length, with a panoramic shoreline of over 200 miles (322 kilometers). Covering an area of 13,000 acres (53 square kilometers), Lake Anna straddles Louisa, Spotsylvania, and Orange counties. In addition to cooling the power plant, Lake Anna is also a popular recreational destination, especially since the opening of Lake Anna State Park in 1983. The two units provide power to northern Virginia and to the greater Richmond area.

The first Westinghouse pressurized water reactor was activated on Lake Anna on June 6, 1978, followed by the second reactor on December 14, 1980.

North Anna Nuclear Generating Station is jointly owned by Dominion Virginia Power Corporation, headquartered in Virginia's capital, Richmond, and Old Dominion Electric Cooperative (ODEC), headquartered in Glen Allen, now a Richmond suburb. North Anna is operated by Dominion Resources Inc., a power and energy company headquartered in Richmond.

Surry Power Station: first nuclear reactors in Virginia

The first two nuclear reactors in Virginia were installed on the south bank of the James River in Surry County. One of the oldest English settlement regions in the Commonwealth, Surry County was established in 1652. Located on Virginia's coastal plain, Surry County conveniently is placed midway between the cosmopolitan giants of Richmond and Virginia Beach. About 13 miles (21 kilometers) to the east of the county seat in the town of Surry, Virginia's first nuclear power plant sits on 840 acres (3.4 square kilometers) near the tip of Hog Island, a peninsula which juts into the Lower James River.

Surry Power Plant has prestigious neighbors. Diagonally across the James River is Historic Jamestowne. Established on Jamestown Island on May 14, 1607, Historic Jamestowne was strategically situated about 60 miles (96 kilometers) from the mouth of the bountiful Chesapeake Bay. The discovery and settlement of this idyllic location were funded by a group of London entrepreneurs whose charter as the Virginia Company was approved on April 10, 1606 by King James I (June 19, 1566–March 27, 1625). For over four centuries this first permanent English settlement in the New World has continued to beguile visitors with its historic remnants and paradisical landscape.

Adjacent to Surry Power Plant, at the peninsula's tip, Hog Island Tract --- resplendent with tidal marshes and controlled ponds, amidst flat, open land of near sea level elevation and pine forests --- is the northernmost segment of Hog Island Wildlife Management Area (HIWMA). Designated as a state wildlife management area on November 15, 1950, HIWMA comprises 3,908 acres (15.82 square kilometers), distributed over three disjunct, or separate, tracts. Southeast of the generating station are the protected area's two other tracts. Carlisle Tract lies upland, at an elevation of about 35 feet (10.6 meters), with timbered areas reforested with loblolly pine (Pinus taeda). There also wildlife food and cover crops are planted along power line rights-of-way. Across Lawnes Creek in Isle of Wight County is the Stewart Tract, with shares 50 acres (0.2 square kilometers) of marshland with the Carlisle Tract.

The first Westinghouse pressurized water reactor, Unit 1, went online at Surry Power Station in December 1972. Unit 2 was activated in May 1973.

Surry Power Station is owned by Dominion Resources, Inc. The station is managed by Dominion Generation, one of the owner corporation's three operating businesses.

Surry Power Station lies over 120 miles (193 kilometers) southeast of Virginia's second generating station on Lake Anna.

Nuclear Regulatory Commission report: high risk rank for North Anna reactors

In August 2010, the Nuclear Regulatory Commission (NRC) released a report which ranked the 104 commercial reactors which are licensed for operation at 65 nuclear power plants in the continental United States. The report was the result of a five year-and-three-months study conducted by NRC staff in conjunction with an independent, non-profit contractor, Electric Power Research Institute (EPRI), headquartered in technologically and scientifically savvy Palo Alto, California. Derived from risk estimates based on 2008 and 1989 geological data, NRC's seismic task force rated each reactor according to susceptibility to core damage from an earthquake, based on U.S. Geological Survey (USGS) data. The reactors were listed from highest risk at number 1 to lowest risk at 104.

The report placed both units of the North Anna Generating Station in the top 10 percent, at 10a and 10b, as most at risk. The risk estimate displayed a 38 percent increase for both reactors at North Anna Power Generating Station. The previous estimate, calculated from 1989 data, established a likelihood of 1 in 31,250. The new estimate, based on 2008 data, expressed the yearly chance at 1 in 22,727.

NRC report: low risk for Surry reactors

On the other hand, both reactors at Surry Power Station were ranked in the bottom 20 percent, at 83a and 83b, as least at risk. With an old estimate of 1 in 175,439 balanced by a new estimate of 1 in 123,457, Surry reactors exhibited a great decrease in risk of -30 percent.

U.S. Geological Survey's seismic hazard map: not much shaking from Virginia quakes

Interestingly, according to the U.S. Geological Survey's seismic hazard map of 2008, the infrequent earthquakes in east central Virginia --- and, in fact, throughout all of the nation's first colony --- are not envisioned as producing violent shaking of the ground at any of its power plants. Depth of the earthquake, frequency of waves emitted by the quake, and distance from epicenter are all factors which intensify or minimize shaking. The seismic hazard map is color coded according to levels of horizontal shaking with a 2-in-100 chance of being exceeded within a 50-year period. Shaking is expressed as a percentage of peak ground acceleration (pga), which is the acceleration of a falling object due to gravity.

Virginia's seismic zone

Yes, Virginia does experience earthquakes. In fact, over 140 earthquakes were experienced in the Commonwealth between 1976 and the first reported earthquake on February 21, 1774, near Petersburg, about 25 miles (40 kilometers) south of Richmond. Normally seismic tantrums in the Old Dominion state whisper their energy waves into quiet dissipation. Nevertheless, the seismic events which rankled the geologic landscape near Mineral on August 23, 2011 trembled into moderately strong waves of energy which radiated lengthily in every direction. This attention-craving quake reminded the United States --- specifically Virginia and its mid-Atlantic stately colleagues --- that there are seismic zones in Virginia and that faults with devastating potentiality exist there. As evinced in historical accounts and in the visual geological record, scatterings of seismic activity are found throughout the state. Nevertheless, quakes primarily are concentrated either in central Virginia along the James River or in southwestern Virginia along the New River Valley in Giles County.

The Mineral earthquake occurred within the central Virginia Seismic Zone, which stretches through central Virginia's Piedmont region with its low, rolling hills and complex geological formations intermingling vastly different materials from widely different ages. This seismic zone, which covers approximately 3,000 square miles (8,000 square kilometers), is far removed from the nearest plate boundaries, which are centered in the Atlantic Ocean and the Caribbean Sea. Nevertheless, this is a zone of persistent --- albeit largely unassuming --- earthquakes due to the lacings throughout of known faults, such as Lakeside and Spotsylvania, ancient faults which are the suspects in Mineral's tremors.

Additionally, although as yet largely undetected, numerous smaller or deeply buried faults are suspected in this stubbornly seismic zone. In fact, the eastern coast is believed to be riddled with faults which are unidentified because of their depth below the earth's surface.

Last 5.9 earthquake in Virginia: May 31, 1897 in Giles County

Virginia was last rattled by a tremblor with a magnitude of 5.9 well over a century ago on Monday, May 31, 1897. That epicenter was located in picturesque Giles County in southwestern Virginia. County residents were disturbed by deafeningly loud, mysterious subterranean grumblings for weeks before the momentous outburst of energy. The warm sunshine of the last day of May was marred by incessant, startling detonations, which were likened to heavy thunder or the explosion of distant artillery.

At 1:58 p.m. the convulsions began, rocking and shaking buildings, jostling furniture, swaying chandeliers and doors to and fro, rattling windows. "The earth seemed to rise and fall in waves" (Richmond Dispatch, June 1, 1897) while houses "were trembling like autumn leaves in a stiff breeze" (Roanoke Times, June 1, 1897). Court proceedings were abandoned, and everywhere terrified people, rushing out of businesses and homes, spilled into the undulating streets. After a few minutes an eerie stillness prevailed, followed by four separate aftershocks between 2 and 5 o'clock that afternoon (Richmond Dispatch, June 4, 1897).

The quake that came to life on the warm, sunshiny last day of May was felt from Georgia northward to Pennsylvania and from the Atlantic Coast westward to Indiana and Kentucky. The quake ultimately laid claim to an area of about 280,000 square miles (725,197 square kilometers). Aftershocks continued for a week, through Sunday, June 6th.

The retrospective assignment of a magnitude of 5.8 to the Giles County earthquake is derived from written accounts of damages in journals and newspapers. Calamities included cracks in brick walls, toppled chimneys, changes in the flow of springs, and muddying of water in springs.

Another way to convey quake severity is with an isoseismal (Greek: ἴσος, isos, “equal” + σεισμός, seismos, "shaking, earthquake"), or "felt area," map. An isoseismal map is derived from perceived intensity of a quake on the basis of descriptive evidence, such as effects on water and types and extent of property damage. This perceived intensity is measured according to the Modified Mercalli scale, which was devised in 1902 by Italian seismologist Giuseppe Mercalli (May 21, 1850-March 19, 1914) as a revision of the Rossi-Forel scale introduced in 1873 by Italian seismologist Michele Stefano Conte de Rossi (1834-1898) and Swiss limnologist François-Alphonse Forel (February 2, 1841-August 7, 1912).

Earthquakes in California vs. those in Virginia: local concentration vs. distant dispersion

Earthquakes on the west coast differ from those on the east coast, specifically in Virginia. In California, for example, where the San Andreas Fault extrudes visibly upon the earth's surface, earthquakes tend to break the earth's surface. Contrarily, faults lying at a depth of 3 to 15 feet (0.9 to 4.5 meters) usually activate quakes in Virginia, so surface faults are uninvolved. Thus, it is easier to attribute accurate blame to the offending faults on the west coast.

Seismic waves travel further in Virginia where the bedrock is strong and well connected, whereas a quake's energy is dissipated quickly close to the epicenter on the west coast where the bedrock is extensively broken up. Thus, a 5.5 magnitude earthquake causes immediate, intense local damage at its epicenter on the west coast but in Virginia clearly is felt well over 300 miles (500 kilometers) away from the epicenter and may cause noticeable damage at a distance of well over 25 miles (40 kilometers). Moreover, the infrequency and general weakness of quakes on the east coast are reflected in reduced concern over establishing quake-proof building standards. Consequently, many buildings on the east coast may be troubled by higher magnitude quakes.

Mineral earthquake: damages and injuries

Aftershocks are still being experienced. For example, an aftershock with 4.5 magnitude was recorded at 05:07:50 UTC (1:07:50 a.m. Eastern daylight time) less than 48 hours later in the early morning hours --- only an hour after midnight --- of Thursday, August 25, 2011. These aftershocks may continue for days, weeks, or even months.

In the meantime, no devastating losses and no fatalities have been reported. Ephemeral inconveniences were encountered, such as:

*** in Washington, D.C., the U.S. Capitol Building was evacuated, the metro ceased, and monuments were closed on National Mall;

*** animals at the National Zoo displayed sensitivity by emitting alarm or distress calls, hiding, huddling, or writhing;

*** 3,000 books shuffled off their shelves onto the floor at the Louisa County Public Library in Mineral.

As for the library books, they were reshelved the next day by volunteers --- including students from Bethany Christian Church in nearby Bumpass --- who just wanted to help.

North Anna Nuclear Generating Station experienced an offsite loss of power, which promptly triggered diesel generators to run the plant's safety systems. Apart from safety protocols, which promptly slid into place, the plant appears to be unaffected.

Nevertheless, consequential damages have occurred:

*** Assuredly irreplaceable family heirlooms have been broken and damaged.

*** A few miles from the epicenter, damage was inflicted on almost every home in the Shannon Glen subdivision of the town of Louisa, the county seat, and only one homeowner there was covered by earthquake insurance.

*** In the nation's capital, 84 miles (135 kilometers) to the northeast, the National Cathedral experienced an estimated million dollars in damage. Battered the most were central tower pinnacles, with the top third of the southwestern pinnacle breaking off --- despite its weight of 3,000 pounds (1,361 kilograms, or 1.5 tons) --- and, fortunately, falling inwards onto the roof instead outwards and down to the ground. Also fortunately the poured concrete roof is supported by massive poured concrete beams and is able to support the toppled weight.

At Virginia Tech, safety personnel efficiently and courteously evacuated library denizens to safety outdoors. The respite outside was brief so definitely attitudes were upbeat. Soon the welcome announcement was made that it was safe to re-enter the library. Conversations momentarily ensued concerning the epicenter. I settled with relief at my research post and was soon transported to the intriguing marine environment of the benevolent Chesapeake Bay.

Mineral earthquake: memorable or forgettable?

Soon this seismic outburst will be only a faint, or even lost, memory for many. Nevertheless, there are many who will not forget Tuesday, August 23, 2011, the day the earthquake dragon rasped a cough outside of Mineral, Virginia, that noisily shrugged its way in any and all directions and revisited a similar event over 100 years before. Those whose lives were disrupted, those who occupationally respond as emergency personnel for public safety, and those who research and study earthquakes will be among the memory-keepers of this day in August which started out, just as in Giles County long before, with sunny warmth.

This hub is dedicated to those who experienced distress as a result of the Mineral, Virginia earthquake and to all the emergency personnel and others who help people and organizations distressed by this earthquake as well as to all those who research and study earthquakes in order to improve our ability as humans to survive when the earth quakes.

***** ***** ***** ***** ***** ***** ***** ***** *****

My special thanks to dedicated individuals/organizations who make their fine images, maps, and exceptional, erudite information available on the internet:

*** Chuck M. Bailey, Professor, Department of Geology, College of William & Mary, Williamsburg --- especially for his "Generalized Geologic Map of the Central Virginia Piedmont with Faults and Earthquakes"

*** Callan Bentley, Professor of Geology, Department of Math Science and Engineering, Northern Virginia Community College, Annandale --- especially for his link to EarthScope USArray visualization

*** David Nash for November 17, 2010 Panoramio photo of "Welcome to Mineral" sign (ID 51793946) (Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License)

*** EarthScope USArray Program

*** Idawriter for January 1, 2007 Panoramio photo of Mineral Avenue, Mineral, Virginia (ID 24774915) (Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License)

*** Kansas Geological Survey

*** Louisa County Library Foundation

*** National Cathedral, Washington, D.C.

*** U.S. Department of Energy

*** U.S. Geological Survey

*** U.S. Nuclear Regulatory Commission

*** Virginia Departments of Mines Minerals and Energy

*** Virginia Tech Seismological Observatory, Blacksburg

Bailey, Chuck. “It’s not my fault.” William & Mary Blogs, August 23, 2011. http://blogs.wm.edu/author/cmbail/ (Last accessed August 25, 2011)

Bailey, Chuck M. “Shaken! Earthquake rocks central Virginia.” What’s New in Virginia Geology: The Geology of Virginia, January 2004. College of William & Mary Department of Geology. http://web.wm.edu/geology/virginia/whats_new/QuakeStory.pdf?svr=www (Last accessed August 25, 2011)

Bentley, Callan. “The Mineral, VA earthquake of August 23, 2011 --- Updated.” Mountain Beltway/American Geophysical Union Blog, August 23, 2011. http://blogs.agu.org/mountainbeltway/2011/08/23/the-mineral-va-earthquake-of-august-23-2011/ (Last accessed August 25, 2011)

“Earthquakes in the Central Virginia Seismic Zone.” Virginia Tech Seismological Observatory Outreach. http://www.geol.vt.edu/outreach/vtso/cvsz.html (Last accessed August 25, 2011)

“Giles County Earthquake of May 31, 1897 News Reports.” Virginia Tech Seismological Observatory Outreach. http://www.geol.vt.edu/outreach/vtso/Giles-Intensity.html (Last accessed August 25, 2011)

Grymes, Charles A. “Virginia Earthquakes.” Virginia Places>The Natural Setting>Rocks and Ridges. http://www.virginiaplaces.org/geology/quake.html (Last accessed August 25, 2011)

“Hog Island.” Marine Protected Areas for the Country United States of America. http://www.mpaglobal.org/index.php?action=showMain&site_code=352930 (Last accessed August 25, 2011)

Hopper, Margaret G., and Gil A. Bollinger. The Earthquake History of Virginia 1774-1900. 1971. Blacksburg VA: Department of Geological Sciences, Virginia Polytechnic Institute and State University, 1971.

Hopper, Margaret G., and G.A. Bollinger. The Earthquake History of Virginia, 1900 to 1980. Blacksburg VA: Department of Geological Sciences, Virginia Polytechnic Institute and State University, 1972.

Imster, Eleanor. “How animals at National Zoo reacted to August 23 D.C. earthquake.” Earthsky>Blogs>Biodiversity. August 24, 2011. http://earthsky.org/biodiversity/how-animals-at-the-national-zoo-reacted-to-earthquake (Last accessed August 25, 2011)

Lasch, David K. “On Earthquakes.” Virginia Minerals, Volume 23 No. 1 (February 1977): 1-12.

“Magnitude 5.8 – Virginia – 2011 August 23 17:51:04 UTC.” Earthquakes>Present>Real-time. U.S. Geological Survey. http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/se082311a.html (Last accessed August 25, 2011)

Sibol, M.S., M.C. Chapman, and S.S. Johnson. “Earthquakes.” Virginia Division of Mineral Resources Fact Sheet. Revised May 2007. http://www.dmme.virginia.gov/DMR3/dmrpdfs/EARTHQUAKES.pdf (Last accessed August 25, 2011)

Stover, Carl W., and Jerry L. Coffman. Seismicity of the United States, 1568-1989. U.S. Geological Survey Professional Paper 1527. Washington DC: U.S. Government Printing Office, 1993.

Tarr, Arthur C., and Russell L. Wheeler. Earthquakes in Virginia and Vicinity 1774 – 2004. U.S. Geological Survey Open-File Report 2006-1017. http://pubs.usgs.gov/of/2006/1017/

U.S. Geological Survey. “The Fall Line.” A Tapestry of Time and Terrain: The Union of Two Maps --- Geology and Topography. http://tapestry.usgs.gov/features/14fallline.html (Last accessed August 25, 2011)

Copyright Thursday, August 25, 2011 by Derdriu