Unusual earthquakes in Alabama, US

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Astronuc
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http://news.yahoo.com/swarm-earthquakes-rattles-rural-alabama-reason-unclear-124125320.html [Broken]
Records from the U.S. Geological Survey show the first of 14 earthquakes occurred on Nov. 20, when a magnitude 3.8 earthquake was recorded about 10 miles northwest of the community of Eutaw. The second occurred in mid-December, followed by another in January and three within a few hours of each other on Feb. 19.

The tremors have continued ever since, with the most recent occurring June 6, when a magnitude 3.0 quake rattled the area. All the tremors have been weaker than the initial jolt in November, . . . .
More than a dozen weak earthquakes have followed in the seven months since in west Alabama's rural Greene County, and geologists are trying to figure out what is causing the seismic swarm in an area of the South more prone to tornadoes than earthquakes.
It will be interesting to know the cause of increased seismic activity in what has been a seismically quiet region.

The eastern US, around the Appalachian mountain chain does have small earthquakes periodically. However the earthquakes are not expected to be strong, but they can occur infrequently.

Tennessee earthquake of July 27, 1977
http://www.bssaonline.org/content/69/4/1081.short

Along the Mississippi River.
2.7 4km NE of Ridgely, Tennessee 2015-06-14 13:11:54 UTC
2.6 8km SE of Ridgely, Tennessee 2015-06-14 07:22:53 UTC

http://pubs.usgs.gov/gip/birth/birth.pdf

https://en.wikipedia.org/wiki/Appalachian_Mountains
https://en.wikipedia.org/wiki/Geology_of_the_Appalachians

Attached image shows locations of earthquakes in SE US from Jan 1, 1970 through today. The zoomed in image shows about 500 earthquakes. The zoomed out image shows 671 earthquakes.
 

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  • #2
DaveC426913
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Perhaps God has convinced Lucifer that his historical hatred of trailer parks is a just cause?
 
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SteamKing
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Charleston, SC was hit by a particularly strong quake in 1886. Prior to the 1906 quake and fire which hit San Francisco, this was one of the most damaging quakes to hit a populated area in the continental US.

https://en.wikipedia.org/wiki/1886_Charleston_earthquake

As damaging as the San Francisco quake was, the strongest quake thought to have occurred in historical times in the eastern US occurred in 1811 near New Madrid, Missouri, approximately in the vicinity of where Missouri, Tennessee,and Kentucky come together:

https://en.wikipedia.org/wiki/1811–12_New_Madrid_earthquakes

Damage caused by these quakes was minimal because the area was sparsely inhabited at the time. These quakes, however, were strong enough to change the course of the Mississippi River in the area affected.

While not particularly active, there are several known fault lines which occur in the SE United States. At one time, the Rev. L.J. Eisele maintained the seismograph station at Spring Hill College in Mobile, and he was noted for issuing the first alerts to the AP about the quake which struck Chile in 1960 and the quake which struck Alaska in 1964.

https://news.google.com/newspapers?...AAIBAJ&sjid=8Z0EAAAAIBAJ&pg=6823,406322&hl=en
 
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Astronuc
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Strong earthquakes > mag 5 are expected in the west coast states of California, Oregon and Washington, but particularly in California, but not so much in the Appalachian states.

On the other hand, they can happen, as recently demonstrated by the 5.8 mag near Mineral, Virginia and the North Anna nuclear plant.
At 1:51 p.m. EDT on August 23, a magnitude 5.8 earthquake occurred near Mineral, Virginia, close to the North Anna Power Station. On August 25 a 4.5 magnitude aftershock was recorded.

http://www.nrc.gov/about-nrc/emerg-preparedness/virginia-quake-info/va-quake-summary.pdf

The North Anna Power Station has two Safe Shutdown Earthquake ground motions, one for structures, systems, and components located on top of rock, which is anchored at 0.12 g, and the other for structures, systems, and components located on top of soil, which is anchored at 0.18 g. The plant has two corresponding Operating Basis Earthquake ground motion spectra, anchored at 0.06 g for rock and 0.09 g for soil.

At several frequencies, the spectral and peak ground accelerations as a result of the August 23, 2011 earthquake were greater than those used for the Operating Basis and Design Basis Earthquakes. These results appear to support the NRC’s current seismic hazard assessment approaches and the basis for Generic Issue 199 reviews.
http://earthquake.usgs.gov/earthquakes/eventpage/usp000j6xc#general_summary
http://earthquake.usgs.gov/earthquakes/events/2011virginia/eost18821.pdf
 

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