Hi 2 cents. When you stand back and look at the picture you can see that the quakes are about 75 miles from the southern end of the (NMSZ) New Madrid Seismic Zone. That is the known portion of the NMSZ. It could be a lot longer then the pictures of the depicted area.

This area is a rift. Sometimes the convection that causes the plates to move will cause them to rip apart. If a continent happens to be sitting over the tear, then it too will be torn, or rifted, apart. Studies have revealed that such rifting apparently began about 600 million years ago beneath the present Mississippi River valley. Although the rift, called the Reelfoot Rift, failed to completely rupture the crust, the pulling apart of the rocks caused the formation of a zone of weakness in the Earth’s crust. As the North American plate pushes against the Pacific plate, compressional forces are probably causing stress on these weakened rocks, which is occasionally relieved when the rocks slip past each other during an earthquake. The Reelfoot Rift extends from Illinois southwest toward the Gulf of Mexico and is bordered to the west by the Commerce Geophysical Lineament (CGL).

The Commerce Geophysical Lineament is a northeast-trending basement magnetic and gravity anomaly - a significant, continental-scale linear feature that is apparent in topography, geophysical data, and remote sensing imagery. It is traceable for over 400 km from central Arkansas into southeast Missouri and southern Illinois to Vincennes, Ind. The Commerce Geophysical Lineament was identified by the U.S. Geological Survey.

New high-resolution seismic reflection data acquired at three sites along the surface projection of the Commerce Geophysical Lineament in southeast Missouri reveal a complex history of faulting and deformation. These data suggest:

1) That earthquake activity in this area has occurred more frequently than would be guessed only on modern recorded earthquake seismicity and

2) The fault structure (or structures) causing the deformation probably pose a seismic hazard to the Central United States.

This current round of quakes and the early 1980 quakes appear to be in, or very near the CGL. Take Care…Don in creepy town