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The New Madrid seismic zone is a source of continuing small and moderate earthquakes, which attest to the high stress in the region and indicate that the processes that produced the large earthquakes over the previous 4,500 years, are still operating.
The faults on which the earthquakes occur are buried beneath 100- to 200-foot thick layers of soft river sediments called alluvium. Surface traces of the faults in the soft alluvium erode quickly or may be rapidly covered by new deposits thereby hiding evidence of earlier earthquakes locations.
New Madrid Seismic Zone (NMSZ), region of poorly understood, deep-seated faults in Earth’s crust that zigzag southwest-northeast through Arkansas, Missouri, Tennessee, and Kentucky, U.S. Lying in the central area of the North American Plate, the seismic zone is about 45 miles (70 km) wide and about.
New Madrid fault and earthquake-prone region considered at high risk today. The 1811–1812 New Madrid earthquakes ( / ˈmædrɪd /) were a series of intense intraplate earthquakes beginning with an initial earthquake of moment magnitude 7.2–8.2 on December 16, 1811, followed by a moment magnitude 7.4 aftershock on the same day.
Photographs 5 and 6 show damage to modern structures close to the epicenter of a magnitude 6.5 earthquake, a small shock compared to the magnitudes (8.4–8.7) of the New Madrid earthquakes. Photographs 8–10 are typical of damage that can occur at large distances from great earthquakes.
At 2:15 a.m. on December 16, 1811, residents of the frontier town of New Madrid, in what is now Missouri, were jolted from their beds by a violent earthquake. The ground heaved and pitched,...
New Madrid earthquakes of 1811–12 - Fault Lines, Seismic Activity, Intensity: Over the past 4,500 years, a number of major earthquakes of magnitude 7.0 to 8.0 occurred in the NMSZ. These events include clusters of large earthquakes that have been dated to 2350 bce, 900 ce, and 1450 ce.
