New Madrid Faults Structures

The Reelfoot Rift The New Madrid Fault system is a collection of reactivated faults that formed long ago when North America began rifting apart. The rifting halted before the continent broke apart, but the structures that formed then are still part of the crust and they have been rejuvenated by the present-day stresses transmitted through the North American Plate. Little evidence of the existence of these faults is visible at Earth's surface but the main structures are outlined by earthquake activity such as that indicated by circles on the map to the right. Most of the seismicity is located between the depths of 5 and 25 kilometers, well beneath the surface.

The fault system actually contains two types of faults, a strike slip segment oriented to the northeast, running from Marked Tree, AR to Caruthersville, MO, and a northwest trending reverse fault that rests below the New Madrid region. Material on the northwest side of the strike-slip fault moves northeast, and up the ramp.

SLU EQ Flyers | SLU EQ Center | Earth & Atmospheric Sciences Prepared by: Charles J. Ammon