New Madrid Fault
The New Madrid Fault
A fault can be defined as a break in the earth materials that causes a relative displacement on both sides of the break. There are two types of recorded faults those that cause earth tremors or earthquakes and are referred to as primary faults and those that result from earthquakes or secondary faults. The New Madrid Fault, also referred to as the New Madrid Seismic Zone, falls in the category of primary faults and is found between 2 and 20 miles beneath the land surface. It is made up of several faults which have been a cause of several earthquakes both past and present that have repeatedly occurred in the Central Mississippi Valley. This fault is invisible, but the secondary faults resulting from it have been visually identified in the New Madrid area (Stewart Knox 36-37). The fault covers a stretch of land from the Marked Tree area in Arkansas State to the Cairo region of Southern Illinois and derives its name from Missouris town of New Madrid which was close to the infamous 1811-1812 earthquakes that shook the region. Earthquakes along the New Madrid Fault are said to have been more disruptive than those of the same magnitude in the U.S West. In 1906 for example, an earthquake in San Francisco, California, that measured 7.8 on the Richter scale was felt in Nevada, about 350 miles away. The New Madrid earthquake of similar magnitude that took place in December 1811 is said to have rung church bells about 1,000 miles away in Massachusettss town of Boston. Such variation has been with geological differences found in the east and west of the U.S Rocky Mountains. Along the New Madrid Fault, there is a lot of geological instability that is manifested through the repeatedly occurring earth tremors in the region (Suburban Emergency Management Project).
The New Madrid Fault refers to a complex of faults and is approximated to be about 120-150 miles long and 50 miles wide and lies along part of the Mississippi River Valley. The fault crosses the river Mississippi about three times and some 5000 square miles of land spanning over five U.S states fall within this zone. Approximately 200 measurable earthquakes take place along the New Madrid Fault every year and the largest 20th century earthquake recorded along this fault was the 1976 quake that measured 5.0 on the Richter scale (Stewart Knox 24-29 Knox, Stewart Schaefer 35). This zone has recorded one of the strongest earthquakes that have ever hit the United States in a series shifting furniture as far away as in Washington and causing church bells to ring in Boston. According to the historical accounts, this series of the earth tremors is also said to have caused a diversion of the river Mississippi near the town of Memphis and the river is even said to have experienced a backflow for some short duration. Geologists have identified the New Madrid Fault line as a major earthquake prone zone and have gone ahead to predict that 50 years may not pass before another strong earthquake most likely as strong as the one that recently hit Haiti has been recorded in the area. Parker states that according to the director of Arkansas Earthquake Center, Haydar Al-Shukri, all the faults are active, creating the likelihood of a high magnitude earthquake in the near future. Such prediction has raised a considerable concern, because the zone runs along one of the most economically disadvantaged areas in the U.S the Delta region. Few people lived in this region during the strongest recorded tremors in the 1800s but today, the region has a very dense population which has been made even larger by the inclusion of St. Louis and Mephis in the zone (Parker 39-40).
Many earthquakes have been recorded in the U.S history, but the strongest of them all were recorded in the New Madrid Fault zone. Between Mid-December of year 1811 and the spring of 1812, the New Madrid Fault generated hundreds of earthquakes all of which would make the head-lines news in the present-day society. At least three to five of these earthquakes are said to have had 8.0 of higher surface magnitudes. Although the modern seismographs had not been invented then, the magnitude of the quakes was so high that it was estimated to have ranged between 8.1 and 7.5 on the Richter scale. The high magnitude of the quake was mainly derived from eyewitness accounts detailing the vents, vast areas affected as well as the massive earth changes that resulted thereafter. According to Knox, Stewart Schaefer, these earthquakes extending over these few months led eyewitnesses to describe them as almost continuous ground shaking (12). On December 16, 1811, three major jolts measuring 8.6, 8.0 and 8.0 ruptured the entire southeastern segment of the New Madrid Fault which covers a stretch of about 90 miles. For about five weeks, there was near calm and then another major earthquake ruptured another 45 miles of the fault. The original town of Point Pleasant disappeared into the river Mississippi, but fortunately with no casualties because its residents had fled during the previous tremors. But he greatest of the earthquakes was felt on February 7, 1812 and the energy released from it is said to have equaled over 8,000 atomic bombs. About 60 miles of the New Madrid Fault ruptured during this earthquake and it is said to have the cause waterfall formation along the River Mississippi as well as the runback of the river. Reelfoot Lake was formed then and most human deaths were also recorded during this earthquake largely because of the caving banks, offshore flooding, log jams and hazardous volumes of floating trees (Knox, Stewart Schaefer 12-13).
What stands out most about these earthquakes is that they were felt over a very large area and ground-shaking from these tremors was reported as far north as Canada the eastern U.S sea boarder and all the way south to New Orleans. Eighteen of the earthquakes were felt over 800 miles away causing little damage as far away as in Washington D.C. They were also felt in every area between the Rocky Mountains and Cuba. The American West did not have any records about the earthquake, largely because the area did not have any big towns that would host newspaper printing but personal diaries have provided records of spectacular local effects resulting from the earthquakes. The February 1812 earth tremor is said to have been so fierce that temporary falls formed along the River Mississippi which crosses the fault at three locations. Overflows along the eastern banks brought back to the river massive chunks of bank material and forest. Fissures opened up in the earth so wide that people had to cut logs to cross them while many log cabins especially in the New Madrid are situated far down the river valley were destroyed. But the most spectacular and also startling effect of the earthquake was perhaps the shooting up of sand and water from the ground to heights as high as 100 feet or approximately 30.5 meters (VanArsdale 16-17 Knox, Stewart Schaefer 16).
Many residents along the New Madrid Fault at the time of the 1811-1812 earthquakes especially the Christians must have thought that the stale odor of hell had finally befallen them when a strong stench from the liquefied sand which contained sulfurous lignite filled the air. The river Mississippi formed dams in several places as well as waterfalls to the amazement and horror of boats going upstream. However, the river also removed all these riverbed flexures within about 11 days and 2oth Century scientists have always viewed these reports with a lot of skepticism. For these scientists, it was difficult to imagine how the Mississippi river bed could have been altered so tremendously by the earthquake. A lake was formed near present-day Blytheville known as Big Lake and the town of Little Prairie disappeared as its terrified residents fled fro their lives. The town of Fort Jefferson in Kentucky was swept away by massive landslides and the slumps are still visible along Highway 51 on the way to the city of Wickliffe. Also swept away was the original town of New Madrid which was washed downstream by the 1812 flash floods. Other physical features altered by the earthquakes were such as land whereby it was either sank or raised a few feet completely altering the drainage system of the area. Swamps were created from dry land while wetlands and lakes became dry as their water was emptied out by the earthquake. Stream channels pouring into the river Mississippi were broken cutting off such towns as St. Francis and Little River from any communication through the river. The earthquake not only altered the Mississippi but practically every other stream along the fault line (Knox, Stewart Schaefer 13-16 VanArsdale 85 Stewart Knox 24).
As a result of the earthquakes that result from the New Madrid Fault, the approximately 5000 square miles covered by the zone has generously been bestowed with seismic features and subsequently become a major tourist attraction. In this are, tourism is an all-season affair because there is something to be enjoyed and seen by the tourists every season. The zone is characterized by the explosion craters, broken streams channels, landslides, earthquake lakes. Secondary faults, sand boils and seismic sand fissures. Yet, not all these features are visible in the course of one single trip to the area because different weather patterns determine how well different features can be seen. Sand fissures and sand boils for example maybe visible in a period of one week but virtually invisible n the next depending on the prevailing weather conditions. A dry season when vegetation cover is low or when adjacent clay soils are wet is the best time to vie sand fissures. During hot and dry mid-summer months for example, sand fissures become easily visible because of the wilting vegetation cover. Seismic sand features are on the other hand more visible during winter when most farmland is completely bare (Knox, Stewart Schaefer 2-3).
The largest sand boil in the world measuring about 136 acres in extent and over one mile long is found in the New Madrid Fault Zone. Some of the fissures, boils and blows are also hone to such natural products as lignite, coal, black shale pieces, carbonized wood and petroliferous nodules. Carboniferous and sulfurous odors emitted by these substances can be smelt in the air. Earthquake lakes are visible as well as places where former earthquake lakes existed but are no more. Out of about a dozen earthquake lakes formed between 1811and 1812, only two still exist today. The rest have either been drained for mosquito control of for agricultural use. But perhaps the most outstanding feature from these 19th century earthquakes is the 812-foot-tall smoke-stack situated at the Associated Electric Company grounds and whose towering presence can be seen as far as 30 miles away (Knox, Stewart Schaefer 3-4).
Although the U.S is yet to record earthquakes of such high magnitude as those resulting from the New Madrid Fault during the 19th century, the region is today one of the most earthquake prone areas east of the U.S Rocky Mountains. Over 3000 earthquakes have been recorded in this area since 1974 the most recent being the 2008 earthquake that was felt along the Wabash Valley Fault and affected the area adjacent to Mt. Carmel Illinois. At the beginning of the century, scientists predicted that another large to moderate earthquake would most likely occur in this region within a 50 years period. If an earthquake would occur in the same magnitude as those recorded between 1811 and 1812, there would certainly be widespread damage, many deaths as well as casualties. This is because the region is now more populated and people go about their daily business wary of any catastrophe that would befall them. Although earthquakes cannot be prevented because they are a natural occurrence, preventive measures should be put in place in such a region in order to reduce the scope or severity of the hazards. One of the steps taken towards these measures is the formation of the Central U.S Earthquake Consortium (CUSEC) which was formed by the emergency management directors from the earthquake prone regions of Arkansas, Missouri, Illinois, Tennessee, Indiana, Mississippi and Kentucky. For several years since the formation of this earthquake awareness body, they have been engaged in drawing earthquake preparedness programs as well as response planning. But a lot more need to be done not only in CUSEC but also in neighboring Central U.S states as well as the states of eastern U.S.A (Diane Publishing Company 39-40).
Predictions have been made that the New Madrid Fault could still be active and the source of future earthquakes of a high magnitude. But other scientists have had a different opinion. An eight year observation by a team of observers from Purdue and Northwestern Universities found out that a major earthquake of the magnitude recorded in 1811-1812 along the New Madrid Fault is less likely to take place. According to the team, the ground around the fault is shifting at a minimal rate of 0.2 mm per year and therefore, there is likelihood that no motion is taking place. Because such a ground movement determines the rate of the energy storage for the next earthquake, a slow movement means that an earthquake would take longer to occur and if the earth stops moving altogether, then a fault could be said to be shutting down. At the rate that ground is moving along the New Madrid Fault, it appears to be slowing down and if it stops altogether, then the risk of earthquakes in this region could be said to be slowly diminishing. But Mother Nature has her own way of determining events and considering that many years have been recorded before any major earthquakes have recurred along the fault chances still stand that the area could produce more tremors after a long time (Fellman).
Conclusion
There is no doubt that the New Madrid Fault has been the subject of much discussion throughout the history of the U.S not only because of the great earth tremors associated with it, but also because of the vast region that it covers. No major tremors have taken place to the scale experienced in 1811-1812 but small earthquakes have regularly been recorded at depths of 4-40 km in the regions of southeastern Missouri, northeastern Arkansas as well as northeastern Tennessee. These earthquakes are said to be occurring within the deeply buried extension of the New Madrid Fault referred to as the Reelfoot Rift. Although some scientists claim that the New Madrid Fault could be closing down and poses les risk of future earthquakes, frequent tremors whether felt or not are an indication that some seismic activity is still active in the region. This leaves the concerned authorities with much to ponder about whether to take necessary action in the event of an earthquake or whether to believe that all fear f such danger is gone and relax. But it has always been safer to take preventive measures over anything catastrophic (VanArsdale 15-16).
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