New Madrid Bicentennial
Several of the largest historical earthquakes to strike the continental United States occurred in the winter of 1811-1812 along the New Madrid Seismic Zone, which stretches from just west of Memphis, Tennessee into southern Illinois. These earthquakes produced at least three temblors between magnitude 7-8, and hundreds of aftershocks.
In 2011 and 2012, there will be events held throughout the central United States observing the 200th Anniversary of the great 1811 and 1812 New Madrid earthquakes that forever changed the mid-western landscape. These quakes were felt across the U.S. and as far south as the Gulf of Mexico, and as far north as Canada. Organizations from across the United States will participate in the bicentennial events, which range from conferences, workshops, public outreach events, multi-state earthquake exercises, field trips, and more.
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.