A series of minor earth tremors (maximum magnitude of just 2.6) have not so much shaken as shivered the Mississippi valley between Paducah and Memphis over the past 30 days.
Though of limited interest in themselves, these tremors call to mind one of the largest series of earthquakes on record in the contiguous United States – the New Madrid earthquakes of 1811 and 1812.
The New Madrid Seismic Zone
For most people, earthquake zones are associated with the planet’s major plate boundaries; and, generally speaking, this is true. In the United States, California and Alaska are the areas most at risk of large earthquakes, with smaller seismic events occurring elsewhere – in the Rockies and (more recently) a continuing swarm of minor tremors in Oklahoma. Most laymen therefore regard the eastern part of the US as more or less immune to major earthquakes.
In reality, this is far from the truth. An ancient plate boundary underlies a section of the Mississippi river valley from Memphis to just south of Indianapolis. That ancient rift, though deeply buried, is nevertheless active and is the source of current minor – and past major – seismic activity.