the most serious data I have encountered yet suggests that really large quakes have occurred around 500 years apart in that area. See the article below and the last graph at the end of the article: https://earthquake.usgs.gov/learn/topics/nmsz/1811-1812.php
The second link covers more of the social/historical details of the great quakes. Observers included Davy Crockett, and James Audubon who was tromping the woods and marshes looking for birds to paint, and others, all made records of their experiences and observations. What has not been included in much of the US sources is that there was also a very powerful earthquake in Venezuela during that period that killed at least 20,000 people.
http://press.uchicago.edu/books/excerpt/2013/valencius_earthquakes.html
Decided to check the Venezuela quake and found this article. The author also tries to tie this in with the events 13,000 years ago that triggered the Younger Dryas cooling event. SC - Post the book if you want.
http://www.scienceforums.net/topic/101806-devolution/
Good idea, it’s been a while since I’ve done that.
Meanwhile, for ****s and giggles:
http://blogs.denverpost.com/library/2013/05/15/the-jupiter-effect-in-march-1982/7878/