New madrid where is it

Even today those URM old buildings, which have not been retro-fitted with safety features, are especially susceptible to earthquake damage. The primary cause of damage and injuries during an earthquake is the destruction of manmade structures and their contents. Particularly susceptible to damage from shaking are:. Damage from earthquakes in the NMSZ will vary depending on the earthquakes location within the zone, magnitude, geologic nature of the material and the degree of urbanization.

The Bootheel area is predominantly rural with scattered, small to medium size towns. Damage to the land by flooding, land substance and lateral spread is likely to be extensive and have a large economic impact in the area as it will disrupt farming.

Thick unfertile sand deposited by sandblows and fissures can impact large areas, as fields graded for irrigation will no longer be level, drainage ditches can become blocked, and transport of materials, supplies and crops will be difficult.

While towns in the Bootheel often do not have tall structures to be damaged by shaking, there are communities that have large open structures and unreinforced masonry URM buildings which are likely to be impacted. Except for along the larger floodplains and areas of loose fill materials, the more distant, densely populated urban area of St.

Louis is not expected to experience major damage to the land by liquefaction. However, its large number of structures and their contents likely will receive impacts from shaking. For Scott, Stoddard and Dunklin counties the percentage estimates are 0. Developing a disaster contingency plan is essential as nearly three quarters of all companies without one will fail within three after a disaster. Facts about the New Madrid Seismic Zone. In the New Madrid region, sand blows can still be seen on the surface today.

In the past, the sand blows were attributed to the earthquakes. We now know that some of the sand blows pre-date and formed as the result of prehistoric New Madrid earthquakes. Photograph and schematic cross-section illustrating earthquake-induced liquefaction and formation of sand dikes and sand blows. The photo was taken on February 14, after the Christchurch, New Zealand earthquake. In the New Madrid seismic zone, many sand blows appear as light-colored sandy patches in plowed fields.

Flood deposits bury other sand blows. Viewed from above, sand blow have circular, elliptical, and linear shapes and can range up to tens of meters in width and hundreds of meters in length. Viewed in cross-section or in excavations and riverbanks, sand blows commonly take the form of large lenses 1 to 2 m in thickness. Sand blows composed of several layers that fine upward from coarse sand to silt and capped by clay probably formed as a result of multiple earthquakes.

Sand blows usually contain clasts, pieces of underlying deposits and soil horizons ripped from the dike walls as the liquefied sand erupted to the surface. The presence of Native Americans is still evident today in the occasional mound not yet destroyed by modern agricultural practices and the abundant potsherds, lithic tools and points, and bone fragments found in plowed fields and river and ditch cutbanks.

Most artifacts encountered during studies of New Madrid sand blows are from the Woodland and Mississippian cultures, which thrived from about B. Both cultural periods are subdivided into early, middle, and late intervals. Woodland ceramics are characterized by grog ground up potsherds or fired clay and sand tempering; whereas, Mississippian ceramics are characterized by shell tempering.

Aerial photograph showing light-colored patches that are sand blow deposits near Lepanto, Arkansas from U. Department of Agriculture, January 26, Although there are uncertainties regarding their age ranges, certain pottery and point types, as well as plant remains, are considered diagnostic of various cultural periods.

Zea maize, or corn, became dominant in the Native American diet about to A. Archaeology has played an important role in recognizing and dating prehistoric earthquake-induced liquefaction features in the New Madrid region.

Sand blows found below Native American mounds and occupation horizons no doubt formed prior to because few Native Americans lived in the area after the 17th Century. Diagnostic artifacts found in association with sand blows provide a preliminary estimate of the age of the causative earthquake. Detailed investigations can further constrain the age of the event.

For example, artifacts in an occupation horizon buried by a sand blow can provide an estimate of the maximum age of the liquefaction feature; whereas, artifacts in an horizon developed in the top of a sand blow can provide an estimate of its minimum age. Similarly, plant remains and other organics found in cultural horizons can be used to date associated sand blows.

Radiocarbon dating of plant remains is the most commonly used dating technique in paleoseismology. It is preferable to have radiocarbon dates from both overlying and underlying horizons to bracket the age of the sand blow.

Log of trench wall at Dodd site near Steele, Missouri, where sand blow and two associated sand dikes are exposed. The pre-event ground surface was displaced downward by 70 to 80 cm between the two sand dikes. Late Mississippian ceramic artifacts found above and below sand blow suggest that it formed between and A.

Radiocarbon dating of charcoal in the soil horizon buried by the sand blow indicates that it formed after A. Radiocarbon dating of a corn kernel collected from a wall trench dug into the top of the sand blow indicates that it formed before A. Therefore, the estimated age of the sand blow is A. Paleoseismology is the study of the timing, location, and magnitude of prehistoric earthquakes preserved in the geologic record.

Knowledge of the pattern of earthquakes in a region and over long periods of time helps to understand the long-term behavior of faults and seismic zones and is used to forecast the future likelihood of damaging earthquakes. In eastern North America, where near-surface faulting is uncommon or difficult to identify, paleoseismology often employs liquefaction features to learn about prehistoric earthquakes.

Earthquake-induced liquefaction features are distinctive and form as the result of strong ground shaking. Liquefaction features include sand blows, dikes, and sills. Sand blows are deposits that form on the ground surface as the result of venting of water and sand. Sand dikes are sediment-filled cracks through which water and sand flowed. Sand sills usually take the form of lenses intruded below clay layers and are connected to sand dikes.

Most large earthquakes around the world have induced liquefaction. In , there were no seismographs in the region until the first seismograph was installed at St. Louis University in Today approximately seismic stations monitor the region in a cooperative network. What many refer to as the Great New Madrid Earthquake, was actually a seismic event made up of 3 major quakes, followed by thousands of aftershocks, ranging from strong damaging quakes and diminishing to weaker quakes that lasted for years after the main shocks.

The 3 main shocks were estimated at magnitudes 7. As there were no seismograph stations in the region at that time, magnitude estimates vary widely from 7. The area of damage is estimated at , square kilometers; the quakes were felt over an area of approximately 5,, square kilometers. The area of strong shaking was approximately 10 times that of the Great San Francisco Earthquake. In addition to the main shocks, 4 aftershocks estimated at greater than 6.

More than aftershocks ranging from large to moderate were reported between December and March An estimated 1, additional aftershocks took place during the same period.

Aftershocks strong enough to be felt extended through Aftershock activity continued over the next decade. The effects of the quakes were extensive and dramatic. Land deformation and elevation changes, both uplift and subsidence, created major land features such as the St. Vast tracts of land were flooded. The most severely affected area is estimated at between 78, and , square kilometers. Nuttli also noted that about eighteen hundred earthquakes of about M3.

The first earthquake of December 16, caused only slight damage to man-made structures, mainly because of the sparse population in the epicentral area. The extent of the area that experienced damaging earth motion, which produced Modified Mercalli Intensity greater than or equal to VII, is estimated to be , square kilometers. However, shaking strong enough to alarm the general population intensity greater than or equal to V occurred over an area of 2. The earthquakes caused the ground to rise and fall - bending the trees until their branches intertwined and opening deep cracks in the ground.

Deep seated landslides occurred along the steeper bluffs and hillslides; large areas of land were uplifted permanently; and still larger areas sank and were covered with water that erupted through fissures or craterlets. Huge waves on the Mississippi River overwhelmed many boats and washed others high onto the shore.

High banks caved and collapsed into the river; sand bars and points of islands gave way; whole islands disappeared. Surface fault rupturing from these earthquakes has not been detected and was not reported, however. The region most seriously affected was characterized by raised or sunken lands, fissures, sinks, sand blows, and large landslides that covered an area of 78, - , square kilometers, extending from Cairo, Illinois, to Memphis, Tennessee, and from Crowley's Ridge in northeastern Arkansas to Chickasaw Bluffs, Tennessee.

Only one life was lost in falling buildings at New Madrid, but chimneys were toppled and log cabins were thrown down as far distant as Cincinnati, Ohio, St. Louis, Missouri, and in many places in Kentucky, Missouri, and Tennessee. A notable area of subsidence that formed during the February 7, , earthquake is Reelfoot Lake in Tennessee, just east of Tiptonville dome on the downdropped side of the Reelfoot scarp.

Subsidence there ranged from 1. Other areas subsided by as much as 5 meters, although 1. Lake St. Francis, in eastern Arkansas, which was formed by subsidence during both prehistoric and the earthquakes, is 64 kilometers long by 1 kilometer wide. Coal and sand were ejected from fissures in the swamp land adjacent to the St. Francis River, and the water level is reported to have risen there by 8 to 9 meters.