Home > New Madrid Seismic Zone

The 150-mile long fault system, which extends into five states, stretches southward from Cairo, Illinois, through Caruthersville and New Madrid, Missouri, through Blytheville, to Marked Tree, Arkansas. It also covers a part of Tennessee, near Reelfoot Lake, extending southeast into Dyersburg.

1 Structure

The New Madrid Seismic Zone is made up of reactivated faults that formed when North America temporarily rifted apart. This rift is known as the Reelfoot Rift and coincides with the northernmost portion of the Mississippi embayment. Most of the seismicity is located from 5 to 25 km beneath the Earth's surface.

The red zones on the map above indicate the epicenter locations of hundreds of minor earthquakeAn earthquake is a trembling or shaking movement of the Earth's surface. Earthquakes typically result from the movement of faults, quasi-planar zones of deformation within its uppermost layers. The word earthquake is also widely used to indicate the sourcs recorded since the 1970's. Two trends are apparent. First is the general NE-SW trend paralleling the trend of the Reelfoot Rift. The second is the intense cross trend, NW-SE, that occurs just southwest of New Madrid. This second trend coincides with an intrusive igneous body which lies deeply buried beneath the sediments of the rift zone. Several other bodies of deeply buried intrusive rock are known to exist within the seismic zone. The depths of these igneous rock bodies closely corresponds to the depth of the seismic activity.

2 In New Madrid

The zone is named after the town of New Madrid, Missouri, the site of three of the most severe North American earthquakes in recorded history, including:

• December 16, 1811Events February 5 George, Prince of Wales becomes Regent because of the perceived insanity of his father, King George III of the United Kingdom. He is known as the Prince Regent. This is the beginning of the period known as the English Regency. March 1 Eg
• January 23, 1812Events January 1 the Allgemeines Burgerliches Gesetzbuch, the Austrian civil code enters into force in the Austrian Empire February 2 Russia establishes a fur trading colony at Fort Ross, California February 7 The strongest in a series of massive earthqua
• February 7, 1812 was the strongest, with estimated magnitude exceeding 8

3 In the fault zone

The New Madrid fault zone lies within the central Mississippi RiverThis page is about the river in the United States; for other uses, see Mississippi River (disambiguation). The Mississippi River is the second-longest river in the United States; the longest is the Missouri River, which flows into the Mississippi. Taken t valley, extending from northeast ArkansasArkansas [akns] is a southern state in the southern United States. The 2000 census was 2,673,400. postal abbreviation is AR. It was admitted in 1836. USS Arkansas was named in honor of this state. History The early French explorers of the state gave it it, through southeast Missouri, western Tennessee, western Kentucky to southern Illinois. Historically, this area has been the site of some of the largest earthquakes in North America. Between 1811 and 1812, four catastrophic earthquakes, with magnitude estimates greater than 7.0 on the Richter scale, occurred during a 3 month period. Hundreds of aftershocks followed over a period of several years. The largest earthquakes to have occurred since then were on January 4, 1843 and October 31, 1895 with magnitude estimates of 6.0 and 6.2 respectively. In addition to these events, seven events of magnitude >= 5.0 have occurred in the area. Instruments were installed in and around this area in 1974 to closely monitor seismic activity. Since then, more than 4000 earthquakes have been located, most of which are too small to be felt. On average one earthquake per year will be large enough to be felt in the area.