http://SaturnianCosmology.Org/ mirrored file For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== *Earthquakes and the New Madrid Seismic Zone * This map shows earthquake epicenters for the central U.S. along the Mississippi River Valley. These earthquakes were recorded instrumentally between 1974 and 1995 by several seismic networks established in the area. More earthquakes occur here than any other part of the United States east of the Rocky Mountains. The area of seismicity is termed the New Madrid Seismic Zone and extends northeast from Arkansas, through southeast Missouri, western Tennessee and Kentucky, then northward into southern Illinois. For more info on earthquakes in Illinois visit this ISGS link: */"Damaging Earthquakes in Illinois - Earthquake Facts"/* , Illinois State Geological Survey, 1995. Or, */Earthquake Hazard in the Heart of the Homeland/* , USGS Fact Sheet FS-131-02. *1811-1812 Great Earthquakes* Historically, this area has been the site of perhaps the largest earthquakes in the conterminous United States. At least three catastrophic earthquakes, with surface-wave magnitudes estimated at greater than 8.0, occurred during the winter of 1811 and 1812. Thousands of aftershocks followed these gigantic quakes throughout the spring and remainder of 1812. The New Madrid Seismic Zone derives its name from the town of New Madrid, Missouri. New Madrid was the closest settlement to the epicenters of the 1811-1812 quakes. It was reported, by eyewitness accounts, that the settlement of New Madrid was totally destroyed. Many of the larger cities, such as St. Louis, Missouri, were only sparsely populated during this time period, and consequently they did not suffer tremendous damage. Several of the largest seismic events were felt throughout much of the central U.S. and along many Atlantic coast cities. The largest earthquakes to have occurred since then were on January 4, 1843 and October 31, 1895 with magnitude estimates of 6.3 and 6.7. The New Madrid Seismic Zone averages about two to three earthquakes a week, most of these tremors are never felt. Usually one to two earthquakes occur per year which are large enough to be noticed regionally by people living in the area. For detailed information on historical New Madrid earthquakes see this original paper written by Otto W. Nuttli entitled */"The Mississippi Valley Earthquakes of 1811 and 1812: Intensities, Ground Motion and Magnitudes"/* /, /Bulletin of the Seismological Society of America. Vol. 63, No. 1, pp. 227-248, February 1973. (*/Seismicity of the United States, 1568-1989 (Revised)/*, by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.) *Potential for Future Earthquakes* The potential for the recurrence of large devastating earthquakes, such as the 1811-1812 series of events, and the effects on heavily populated cities within and adjacent to the New Madrid Seismic Zone has sparked a great deal of ongoing research concerning mitigation and hazard reduction of possible future earthquakes. If an event equal in magnitude to the largest 1811-1812 quake occurred today, it is estimated that the loss of life would be great and property damage would be in the billions of dollars. Many scientists believe we are overdue for a large (>6.0) earthquake, and that through research, public awareness, and emergency preparedness may be able to substantially decrease these estimated losses. Based upon historically and instrumentally recorded earthquakes, some scientists suggest the probability for a magnitude 6.0 or greater earthquake is 25-40% in the next 50 years and a 7-10% probability for a magnitude 7.5-8.0 within the next 50 years (/source/: USGS Fact Sheet FS-131-02 ) Current geologic research indicates the area has a very long earthquake history. Studies of subsurface geologic structures related to the earthquake seismicity indicate the presence of ancient fault zones which were created more than 500 million years ago when rifting of the earth's crust tried to split the continent apart. Information gathered by geoscientists researching the seismicity problem indicates that these ancient faults are being reactivated by a southwest to northeast oriented compressive stress field resulting in earthquakes today. By closely monitoring earthquake activity and conducting investigations which image the subsurface geology, scientists hope to better understand the nature of earthquakes in the New Madrid Seismic Zone. Perhaps one day this information will be used to save many lives and billions of dollars. For an overview and discussion on the geologic structures that cause earthquakes in this region read */"Uncovering Hidden Hazards in the Mississippi Valley"/* , by Thomas G. Hildenbrand /et al.,/ U.S. Geological Survey Fact Sheet 200-96 1996. Robert B. Olshansky /et al. /of the Mid-America Earthquake Center, University of Illinois has prepared a report (late 2003) entitled */"Evaluating Earthquake Risk in Mid-America Communities"/* (/large 139 page PDF document, 2.3 mb/).