Crustal geophysics gives insight into new madrid seismic zone



The New Madrid seismic zone (NMSZ) is the most active seismic zone in the United States east of the Rocky Mountains. Frequency-magnitude relationships show that an earthquake magnitude of 6.3 or greater can be expected in this area about once every 100 years, on average [Johnston and Nava, 1985]. During the winter of 1811–1812, three earthquakes of moment magnitude near 8 devastated New Madrid, Mo., and the surrounding region. Today, if an earthquake in the magnitude 6–7 range were to strike, in addition to loss of life and injuries, residents would suffer about $3.6 billion in immediate property losses [Algermissen, 1991] and feel the pinch of a long-term economic impact.