New Madrid Seismic Zone The New Madrid Seismic Zone, along the Mississippi River near New Madrid, Missouri, between Memphis and St. Louis, is related to an aulacogen (failed rift) that formed at the same time as the Gulf of Mexico. This area is still quite active seismically. Four great earthquakes in 1811 and 1812, estimated at 8 on the Richter magnitude scale, had tremendous local effects in the then sparsely settled area, and were felt in many other places in the Midwestern and eastern U.S. These earthquakes created Reelfoot Lake in Tennessee from the altered landscape near the river.
new maDRId seismIC zONE the neW maDriD SEiSmIc ZOnE, alonG the miSsISsippi river nEaR new mAdRid, missouri, beTweEn MemphiS aNd sT. louis, is Related to an AULACOgeN (failed Rift) tHaT fORmEd at the sAmE TIME As thE gulf of mexicO. tHIs aRea IS Still qUITe active seiSmiCAlLy. four Great earthqUAkes iN 1811 aNd 1812, eStimaTed at 8 on tHe rIchTeR mAGNiTUde scale, had trEmenDous locAl effeCTs in tHE theN sparsely settled aREa, AnD were fElt in mAnY othEr plaCes IN the midwestern And easteRn u.s. thEse eARthquaKes creAtED rEElFoOt lAke in tennEssee fRom the aLtEreD lAndscapE Near THe RiVer.