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July 3, 2016 Weekly Geology Guess

July 3, 2016
Greetings from the Bluff Park   Porch, way up yonder on Shades Mountain (1,109′) in Alabama:

My discussion on Alabama Geology will continue with the with Alabama Earthquakes.


Minerals and Rocks – The Good Life from the Ground

“If it ain’t grown, it has to be mined”

Earthquakes in Alabama?



“Alabama experiences frequent small earthquakes detectable only by instruments, and occasional moderate earthquakes large enough to be felt over a wide area and resulting in minor damage.[7][8] The largest earthquake in recorded Alabama history measured an estimated magnitude of 5.1 and occurred October 18, 1916 near Irondale, and resulted in widespread panic, damage to structures, and dramatic changes in water well levels.[9] Since 1886, slightly more than 10 percent of earthquakes with an epicenter in Alabama have been an estimated magnitude 3 or greater. The April 29, 2003 earthquake centered near Fort Payne, Alabama was felt over a wide area and received extensive media coverage.[10]

Two fault zones are found in Alabama, the Southern Appalachian Seismic Zone (also known as the Eastern Tennessee Seismic Zone) in northeast and central Alabama, and the Bahamas Fracture Seismic Zone in southwest Alabama.[7] Alabama also lies within the influence of the New Madrid Seismic Zone and the South Carolina Seismic Zone, earthquakes in those zones have resulted in damage in Alabama. The northeast corner of the state is subject to the greatest peak accelerations due to the presence of the East Tennessee Seismic Zone”.Geology of Alabama – Wikipedia, the free encyclopedia

Alabama Earthquake History.

New Madrid Seismic Zone

>    A couple of years ago, FEMA and the supporting state agencies surrounding the New Madrid Seismic Zone performed a computer based exercise for a magnitude 8.0 earthquake South of St. Louis.  = Not good, major, major damage and loss of life.

1916, Irondale, Alabama Earthquake

Recent Earthquake Activity in Alabama

This is what is so exciting about geological science.  It is like an endless mystery movie.

Figure 6 is unique, in that it shows our old buddy, the Grenville Orogeny (mountain building) at depth in Alabama.


References include:

–    Wikipedia


Editors Note:  It is the intent of this site to keep this discussion as simple as possible, so as to educate the interested general public and not to discuss with the geology crowd the latest geologic theories and nuances.  Thanks, R



“No copyright infringement intended.
The rights belong to their respective owners”


Copyright Disclaimer: Under Section 107 of the Copyright Act 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.


Author’s Request:  If you see any pictures that you know the source and photographer, let me know immediately.  Thanks!  R

Images have been searched by TinEye Reverse Image Search.


Next week we will continue our Alabama Geology Search into its many and varied fossils.





1.  SE_USA- Seismic Zones.

1. SE_USA- Seismic Zones.

2.  AL Earthquakes, Historic.

2. AL Earthquakes, Historic.


2003 AL Earthquake, Ft. Payne. by Unknown

4.  SE Tect. Overview. by Unknown

4. SE Tect. Overview. by Bill Thomas

5.  New Madrid Damage, 7.2.

This map shows areas damaged by the Dec. 16, 1811, magnitude 7.2 earthquake. That earthquake was the first of three major temblors along the New Madrid fault in 1811 and 1812. (Image courtesy of Seth Stein, based on results by Susan Hough)

6.  New Eastern US Faults. Grenville Orogeny. by Mark G. Steltenpohl, Isidore Zietz, J. Wright Horton, Jr

6. New Eastern US Faults. Grenville Orogeny Fault System. by Mark G. Steltenpohl, Isidore Zietz, J. Wright Horton, Jr

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