Hi Chris. According to Dr. Mark Zoback of the Stanford University glaciers may be the cause of the New Madrid quakes. The theory that the New Madrid Fault Zone is a failed rift seems to still be holding up. Up until about 20,000 years ago glaciers covered this area. Being as how it is a failed rift zone this would mean that the crust in this area is somewhat on the thin side. The weight of those glaciers compressed the earth in that area. With the weight now removed the earth is trying to return to its original elevation. Take Care…Don in creepy town

“Freed from the heavy pressure of the ice sheet, North America slowly rose. This glacial rebound continues even today and triggers quakes in the New Madrid fault zone in Missouri, Kentucky, Arkansas and Tennessee, says Stanford geophysicist Mark Zoback.”

"It's the only hypothesis we have that I think satisfies all the diverse observations," Zoback says, "especially that big earthquakes in this region appear to have been turned on during the past few thousand years."

• New Madrid