(8/23) Much of the region of the Eastern United States, from North Carolina to New England, and Ohio, were shaken around 1:30 p.m. Aug. 23 as the result of a deep-earth earthquake centered in Mineral, Va., a town of about 400, not far from Fredericksburg and Spotsylvania.
The epicenter of the circa 5.8 magnitude quake occurred around three miles below the rural Virginia countryside in highly crystallized, metamorphic rock layers dating back hundreds of millions of years in age, according to the United States Geological Survey.
The energy released by a 5.8-magnitude quake equals about half the power of the atomic bomb that was dropped at the conclusion of World War II on Hiroshima, Japan, according to an article posted on the Weather Channel.
The quake was felt in North Carolina, Virginia, Maryland, Pennsylvania, New York, Ohio, and in New England to Rhode Island. Tremors were also felt in Toronto.
Most of the region affected reported shaking that lasted up to 30 seconds or more, some reporting that the 30-second blast seemed to have occurred in two waves.
No cataclysmic damage was reported, although some areas, such as Baltimore, experienced wall and façade collapses. Roof collapses were also reported, but no widespread damage occurred, according to the various media. Mineral, Va., suffered various structural damages, with no reported injuries.
Transportation systems and some government and commercial buildings were shut down for various periods of time following the quake to allow engineers to evaluate their integrity.
Phone systems were overwhelmed for about an hour due to heavy volume, and in some cases cell and cable service were off-line.
Jennifer Staiger, professor of Biology at Mount Saint Mary’s University and wife of Emmitsburg Town Council President Christopher V. Staiger, stated that she was at a university colleague’s house in Carroll County when the earth quake hit.
"We were sitting around and felt vibrations first. Our first immediate response was thinking that something had gone wrong with the furnace," she said. Then "as it escalated the house began shaking and things started rattling on the wall, water began vibrating in the glasses and the chandelier started shaking," she said.
The accompanying noise, Staiger said, "was sort of like a freight train sound." Her husband then called and asked her if she had felt the shaking and (they) "figured out it was an earthquake."
Staiger said Mount Saint Mary’s University did activate their early warning siren, and evacuated the students in order to check the structural integrity of the various campus buildings before allowing the students back inside.
Emmitsburg area resident Audrey Hillman said, when the quake first struck, "My initial thought was it was construction. I felt the house shake. Then I didn’t know what to think."
"I have a decorative bird that stands about three feet tall and it was moving like crazy and I did hear a rumble (at the same time). The house kind of moved," she stated.
"It’s that kind of a moment that you have (because the region doesn’t generally experience noteworthy quakes) when you think, ‘What the hell was that?,‘" Hillman said. "It was a wake-up call too. People need to be educated now (about earthquakes in the East)."
Linda Ballenger, co-owner of Buck Forest Farm, Rocky Ridge, said she was sitting at the computer posting on her Facebook page when "It seemed as if my chair dropped out from under me. I felt lightheaded and a bit dizzy (and) thought I was about to pass out."
"After a few seconds, I went into the kitchen, along with my son Jay, and we watched things hanging on the walls sway back and forth."
Her daughter, Emily was in the farm barn and "she knew right away what had happened, as she has been through several quakes (while serving in the U.S. Air Force) in Japan."
Unlike the Mid-West and West Coast, earthquakes in the eastern portion of the country are not caused by plate tectonics (the movement of continental and sub continental plates).
Eastern quakes are generally the byproduct of the slippage of prehistoric fault systems, the opposing sides of which had, at some point in the past, become snagged on each other. Pressures eventually build up and end the passé, resulting in one of the opposing sides breaking free and slipping.
When deep quakes occur in the very ancient crystallized layers, the vibrations tend to travel great distances (up to hundreds of miles), just as high-quality crystalware will ring throughout, when struck by a metal object.
Aftershocks have been occurring in the Mineral, Va. region, and will likely continue for over a week, according to geologists.
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