New Madrid seismic fault zone

The largest system of geological faults in the eastern USA, centred on New Madrid, Missouri. There are several hundred earthquakes along the fault every year, more than anywhere else in the USA east of the Rocky mountains; but most of them are too small to be felt. A series of very severe earthquakes in 1811–12 created a lake 22 km/14 mi long and was felt as far away as Washington, DC, and Canada. Strong earthquakes would cause much damage because the solid continental rocks would transmit the vibrations over a wide area, and buildings in the region have not been designed with earthquakes in mind.

The zone covers a rift in the continental plate running 200 km/125 mi along the Mississippi River from northern Arkansas to southern Illinois.