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General Information Product 134

20 Cool Facts about the New Madrid Seismic Zone

Commemorating the Bicentennial of the New Madrid Earthquake Sequence December 1811–February 1812

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This poster summarizes a few of the more significant facts about the series of large earthquakes that struck the New Madrid seismic zone of southeastern Missouri, northeastern Arkansas, and adjacent parts of Tennessee and Kentucky from December 1811 to February 1812. Three earthquakes in this sequence had a magnitude (M) of 7.0 or greater. The first earthquake occurred on December 16, 1811, at 2:15 a.m.; the second on January 23, 1812, at 9 a.m.; and the third on February 7, 1812, at 3:45 a.m. These three earthquakes were among the largest to strike North America since European settlement. The mainshocks were followed by many hundreds of aftershocks that occurred over the next decade. Many of the aftershocks were major earthquakes themselves. The area that was strongly shaken by the three main shocks was 2–3 times as large as the strongly shaken area of the 1964 M9.2 Alaskan earthquake and 10 times as large as that of the 1906 M7.8 San Francisco earthquake. Geologic studies show that the 1811–1812 sequence was not an isolated event in the New Madrid region. The 1811–1812 New Madrid earthquake sequence was preceded by at least two other similar sequences in about A.D. 1450 and A.D. 900. Research also indicates that other large earthquakes have occurred in the region surrounding the main New Madrid seismicity trends in the past 5,000 years or so.

First posted September 30, 2011

For additional information contact:

Center Director,
USGS Geologic Hazards Science Center
Box 25046, Mail Stop 966
Denver, CO 80225

This report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Williams, R.A., McCallister, N.S., and Dart, R.L., 2011, 20 cool facts about the New Madrid Seismic Zone—Commemorating the bicentennial of the New Madrid earthquake sequence, December 1811–February 1812 [poster]: U.S. Geological Survey General Information Product 134.


First Mainshock Earthquake

First steamboat voyage interrupted

Riverbanks caved, widespread flooding

Second Mainshock Earthquake

Only 5,700 people lived in St. Louis in 1811


Third Mainshock Earthquake

Homemade seismograph records quakes in Cincinnati

Widespread ground failure and sand blows

Reelfoot Lake forms

Thousands of aftershocks

It had happened before 1811

Archaeological age constraints on earthquake timing

First Disaster Relief Act

More quakes—M6.0 in 1843, M6.6 in 1895

1909—Seismograph installed at Saint Louis University

Growth of seismograph network

Another quake—M5.0 in 1976

Will a damaging earthquake occur again

Most seismically active area east of the Rockies

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