New Madrid Seismic Zone

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Coordinates: 36°35′N89°35′W / 36.58°N 89.59°W / 36.58; -89.59

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Reelfoot Rift and the New Madrid Seismic Zone in a 3D topographic image
NMSZ Erdbeben.jpg
Magnetic potential map of the Reelfoot Rift

The New Madrid Seismic Zone ( /ˈmædrɪd/ ), sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.

The New Madrid fault system was responsible for the 1811–12 New Madrid earthquakes, and has the potential to produce large earthquakes in the future. Since 1812, frequent smaller earthquakes have been recorded in the area. [1]

Earthquakes that occur in the New Madrid Seismic Zone potentially threaten parts of eight American states: Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee, Oklahoma, and Mississippi. [2]

Location

The 150-mile (240 km)-long seismic zone, which extends into five states, stretches southward from Cairo, Illinois; through Hayti, Caruthersville, and New Madrid in Missouri; through Blytheville into Marked Tree in Arkansas. It also covers a part of West Tennessee, near Reelfoot Lake, extending southeast into Dyersburg. It is southwest of the Wabash Valley Seismic Zone.

Most of the seismicity originates between 3 and 15 miles (4.8 and 24.1 km) beneath the Earth's surface.[ citation needed ]

Earthquake history

The zone had four of the largest North American earthquakes in recorded history, with moment magnitudes estimated to be as large as 7.0 or greater, all occurring within a 3-month period between December 1811 and February 1812. Many of the published accounts describe the cumulative effects of all the earthquakes (known as the New Madrid Sequence), so finding the individual effects of each quake can be difficult. Magnitude estimates and epicenters are based on interpretations of historical accounts and may vary.

Prehistoric earthquakes

Because uplift rates associated with large New Madrid earthquakes could not have occurred continuously over geological timescales without dramatically altering the local topography, studies have concluded that the seismic activity there cannot have gone on for longer than 64,000 years, making the New Madrid Seismic Zone (NMSZ) a young feature, or that earthquakes and the associated uplift migrate around the area over time, or that the NMSZ has short periods of activity interspersed with long periods of quiescence. [3] Archaeological studies have found from studies of sand blows and soil horizons that previous series of very large earthquakes have occurred in the NMSZ in recent prehistory. Based on artifacts found buried by sand blow deposits and from carbon-14 studies, previous large earthquakes like those of 1811–1812 appear to have happened around AD 1450 and 900, [4] as well as around AD 300. Evidence has also been found for an apparent series of large earthquakes around 2350 BC. [5] About 80 km southwest of the presently defined NMSZ, but close enough to be associated with the Reelfoot Rift, near Marianna, Arkansas, two sets of liquefaction features indicative of large earthquakes have been tentatively identified and dated to 3500 and 4800 BC. These features were interpreted to have been caused by groups of large earthquakes timed closely together. [6]

Dendrochronology (tree ring) studies conducted on the oldest bald cypress trees growing in Reelfoot Lake found evidence of the 1811–1812 series in the form of fractures followed by rapid growth after their inundation, whereas cores taken from old bald cypress trees in the St. Francis sunklands showed slowed growth in the half century that followed 1812. These were interpreted as clear signals of the 1811–1812 earthquake series in tree rings. Because the tree ring record in Reelfoot Lake and the St. Francis sunk lands extend back to 1682 and 1321, respectively, Van Arsdale et al. interpreted the lack of similar signals elsewhere in the chronology as evidence against large New Madrid earthquakes between those years and 1811. [7]

December 25, 1699

The first known written record of an earthquake felt in the NMSZ was from a French missionary traveling up the Mississippi with a party of explorers. At 1 pm on Christmas Day 1699, at a site near the present-day location of Memphis, the party was startled by a short period of ground shaking. [8]

The Great Earthquake at New Madrid, a 19th-century woodcut from Devens' Our First Century (1877) New Madrid Erdbeben.jpg
The Great Earthquake at New Madrid, a 19th-century woodcut from Devens' Our First Century (1877)

1811–12 earthquake series

At New Madrid, trees were knocked down and riverbanks collapsed. This event shook windows and furniture in Washington, DC, rang bells in Richmond, Virginia, sloshed well water and shook houses in Charleston, South Carolina, and knocked plaster off of houses in Columbia, South Carolina. In Jefferson, Indiana, furniture moved, and in Lebanon, Ohio, residents fled their homes. Observers in Herculaneum, Missouri, called it "severe" and said it had a duration of 10–12 minutes. [13]
Aftershocks were felt every 6-10 minutes, a total of 27, in New Madrid until what was called the Daylight Shock, which was of the same intensity as the first. Many of these were also felt throughout the eastern US, though with less intensity than the initial earthquake. [13]
More than 4000 earthquake reports since 1974 New Madrid Seismic Zone activity 1974-2011.svg
More than 4000 earthquake reports since 1974

1812–1900

Hundreds of aftershocks of the 1811–1812 series followed over a period of several years. Aftershocks strong enough to be felt occurred until 1817. The largest earthquakes to have occurred since then were on January 4, 1843, and October 31, 1895, with magnitude estimates of 6.0 and 6.6, respectively. The 1895 event had its epicenter near Charleston, Missouri. The quake damaged virtually all the buildings in Charleston, created sand volcanoes by the city, cracked a pier on the Cairo Rail Bridge, and toppled chimneys in St. Louis, Missouri; Memphis, Tennessee; Gadsden, Alabama; and Evansville, Indiana. [14]

Modern activity

The largest NMSZ earthquake of the 20th century was a 5.4-magnitude quake (although it was reported as a 5.5 at the time) on November 9, 1968, near Dale, Illinois. The quake damaged the civic building at Henderson, Kentucky, and was felt in 23 states. People in Boston said their buildings swayed. At the time of the quake, it was the biggest recorded quake with an epicenter in Illinois in that state's recorded history. [15] In 2008 in the nearby Wabash Valley Seismic Zone, a similar magnitude 5.4 earthquake occurred with its epicenter in Illinois near West Salem and Mount Carmel.

Instruments were installed in and around the area in 1974 to closely monitor seismic activity. Since then, more than 4,000 earthquakes have been recorded, most of which were too small to be felt. On average, one earthquake per year is large enough to be felt in the area.

Geology

Geological structure of Reelfoot Rift Reelfoot Rift diagram from USGS en.svg
Geological structure of Reelfoot Rift

The faults responsible for the NMSZ are embedded in a subsurface geological feature known as the Reelfoot Rift that formed during the breakup of the supercontinent Rodinia in the Neoproterozoic era (about 750 million years ago)[ citation needed ]. The resulting rift system failed to split the continent, but has remained as an aulacogen (a scar or zone of weakness) deep underground, and its ancient faults appear to have made the Earth's crust in the New Madrid area mechanically weaker than much of the rest of North America.

This relative weakness is important, because it would allow the relatively small east-west compressive forces associated with the continuing continental drift of the North American plate to reactivate old faults around New Madrid, making the area unusually prone to earthquakes in spite of it being far from the nearest tectonic plate boundary. [16]

Since other ancient rifts are known to occur in North America, but not all are associated with modern earthquakes, other processes could be at work to locally increase mechanical stress on the New Madrid faults. [17] [18] Also, some form of heating in the lithosphere below the area has been suggested to be making deep rocks more plastic, which would concentrate compressive stress in the shallower subsurface area where the faulting occurs. [19] [20]

Earthquakes in the New Madrid and Wabash Valley seismic zones New Madrid and Wabash seizmic zones-USGS.png
Earthquakes in the New Madrid and Wabash Valley seismic zones

Potential for future earthquakes

In a report filed in November 2008, the U.S. Federal Emergency Management Agency warned that a serious earthquake in the NMSZ could result in "the highest economic losses due to a natural disaster in the United States," further predicting "widespread and catastrophic" damage across Alabama, Arkansas, Illinois, Indiana, Kansas, Kentucky, Mississippi, Missouri, Oklahoma, Texas, and particularly Tennessee, where a 7.7 magnitude quake would cause damage to tens of thousands of structures affecting water distribution, transportation systems, and other vital infrastructure. [21] The earthquake is expected to also result in many thousands of fatalities, with more than 4,000 of the fatalities expected in Memphis alone.

The potential for the recurrence of large earthquakes and their effects today on densely populated cities in and around the seismic zone has generated much research devoted to understanding in the NMSZ. By studying evidence of past quakes and closely monitoring ground motion and current earthquake activity, scientists attempt to understand their causes and recurrence intervals.

In October 2009, a team composed of University of Illinois and Virginia Tech researchers headed by Amr S. Elnashai, funded by the Federal Emergency Management Agency, considered a scenario where all three segments of the New Madrid fault ruptured simultaneously with a total earthquake magnitude of 7.7. The report found that there would be significant damage in the eight states studied – Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri, and Tennessee – with the probability of additional damage in states farther from the NMSZ. Tennessee, Arkansas, and Missouri would be most severely impacted, and the cities of Memphis, Tennessee, and St. Louis, Missouri, would be severely damaged. The report estimated 86,000 casualties, including 3,500 fatalities, 715,000 damaged buildings, and 7.2 million people displaced, with two million of those seeking shelter, primarily due to the lack of utility services. Direct economic losses, according to the report, would be at least $300 billion. [22]

Iben Browning's 1990 prediction

Beginning in February 1989, self-proclaimed climatologist Iben Browning, who claimed to have predicted the 1980 eruption of Mount St. Helens and the 1989 Loma Prieta earthquake – predicted a 50% probability of a magnitude 6.5 to 7.5 earthquake in the New Madrid area sometime between December 1 and December 5, 1990. [23] [24] Browning appears to have based this prediction on particularly strong tidal forces being expected during that time, and his opinion that a New Madrid earthquake was "overdue;" however, seismologists generally agree that no correlation exists between tides and earthquakes. [24] The United States Geological Survey (USGS) requested an evaluation of the prediction by an advisory board of earth scientists, who concluded, "the prediction does not have scientific validity." [24] Despite the lack of scientific support, Browning's prediction was widely reported in international media, causing public alarm. The period passed with no major earthquake activity in New Madrid or along the 120-mile (190 km) fault line. [24]

Uncertainty over recurrence potential

The lack of apparent land movement along the New Madrid fault system has long puzzled scientists. In 2009, two studies based on eight years of GPS measurements indicated that the faults were moving at no more than 0.2 mm (0.0079 in) a year. [25] This contrasts to the rate of slip on the San Andreas Fault, which averages up to 37 mm (1.5 in) a year across California. [26]

On March 13, 2009, a research group based out of Northwestern University and Purdue University, funded by the USGS, reported in Science and other journals that the New Madrid system may be "shutting down" and that tectonic stress may now be accumulating elsewhere. [25] Seth Stein, the leader of the research group, published these views in a book, Disaster Deferred, in 2008. Although some of these ideas have gained some acceptance among researchers, they have not been accepted by the National Earthquake Prediction Evaluation Council, which advises the USGS. [27]

In the November 5, 2009, issue of Nature , researchers from Northwestern University and the University of Missouri said that due to the lack of fault movement, the quakes along the faults may only be aftershocks of the 1811–1812 earthquakes. [28]

According to the USGS, a broad consensus exists that the possibility of major earthquakes in the NMSZ remains a concern, and that the GPS data do not provide a compelling case for lessening perceived earthquake hazards in the region. One concern is that the small earthquakes that still happen are not diminishing over time, as would be if they were aftershocks of the 1811–1812 events; another is that the 4,500-year archaeological record of large earthquakes in the region is more significant than 10 years of direct strain measurement. The USGS issued a fact sheet in 2009 stating the estimate of a 7–10% chance of a New Madrid earthquake of magnitude comparable to one of the 1811–1812 quakes within the next 50 years, and a 25–40% chance of a magnitude 6.0 earthquake in the same time frame. [29]

In July 2014, the USGS increased the risk assessment for the New Madrid area. [30]

See also

Related Research Articles

Earthquake Shaking of the surface of the earth caused by a sudden release of energy in the crust

An earthquake is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the air, and wreak destruction across entire cities. The seismicity, or seismic activity, of an area is the frequency, type, and size of earthquakes experienced over a period of time. The word tremor is also used for non-earthquake seismic rumbling.

Intraplate earthquake Earthquake that occurs within the interior of a tectonic plate

The term intraplate earthquake refers to a variety of earthquake that occurs within the interior of a tectonic plate; this stands in contrast to an interplate earthquake, which occurs at the boundary of a tectonic plate.

An aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to known laws. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms.

1811–1812 New Madrid earthquakes Series of earthquakes during 1811-1812 impacting on Missouri USA

The 1811–1812 New Madrid earthquakes 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. Two additional earthquakes of similar magnitude followed in January and February 1812. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. The earthquakes, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory and now within the U.S. state of Missouri.

An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years.

2003 San Simeon earthquake

The 2003 San Simeon earthquake struck at 11:15 PST on December 22 on the Central Coast of California, about 7 miles (11 km) northeast of San Simeon. Probably centered in the Oceanic fault zone within the Santa Lucia Mountains, it was caused by thrust faulting and the rupture propagated southeast from the hypocenter for 12 miles (19 km).

2008 Illinois earthquake

The 2008 Illinois earthquake was one of the largest earthquakes ever recorded in the Midwest state of Illinois. This moderate strike-slip shock measured 5.2 on the moment magnitude scale and had a maximum Mercalli intensity of VII. It occurred at 04:36:59 local time on April 18 near West Salem and Mount Carmel, Illinois, within the Wabash Valley Seismic Zone. Earthquakes in this part of the country are often felt at great distances.

Wabash Valley Seismic Zone

The Wabash Valley Seismic Zone is a tectonic region located in the Midwest of the United States, centered on the valley of the Lower Wabash River, along the state line between southeastern Illinois and southwestern Indiana.

1968 Illinois earthquake Largest recorded earthquake in Illinois, US

The 1968 Illinois earthquake was the largest recorded earthquake in the U.S. Midwestern state of Illinois. Striking at 11:02 am on November 9, it measured 5.4 on the Richter scale. Although no fatalities occurred, the event caused considerable structural damage to buildings, including the toppling of chimneys and shaking in Chicago, the region's largest city. The earthquake was one of the most widely felt in U.S. history, largely affecting 23 states over an area of 580,000 sq mi (1,500,000 km2). In studying its cause, scientists discovered the Cottage Grove Fault in the Southern Illinois Basin.

Brawley Seismic Zone

The Brawley Seismic Zone (BSZ), also known as the Brawley fault zone, is a predominantly extensional tectonic zone that connects the southern terminus of the San Andreas Fault with the Imperial Fault in Southern California. The BSZ is named for the nearby town of Brawley in Imperial County, California, and the seismicity there is characterized by earthquake swarms.

1916 Irondale earthquake Earthquake in Alabama on October 18, 1916

The 1916 Irondale earthquake struck in the north–central region of the U.S. state of Alabama on October 18. The strongest earthquake in state history, it registered an estimated Richter scale magnitude of 5.1 and resulted in extensive, but minor damage. This damage, limited to Shelby and Jefferson counties, reached its maximum severity near the epicenter in the city of Irondale, including cracked windows, fallen chimneys, and dried-up wells. While there were no fatalities, the earthquake spawned widespread panic, sending alarmed workers from tall buildings.

1995 Gulf of Aqaba earthquake

The 1995 Gulf of Aqaba earthquake occurred on November 22 at 06:15 local time and registered 7.3 on the Mw scale. The epicenter was located in the central segment of the Gulf of Aqaba, the narrow body of water that separates Egypt's Sinai Peninsula from the western border of Saudi Arabia. At least 8 people were killed and 30 were injured in the meizoseismal area.

Earthquake activity in the New York City area

Although the eastern United States is not as seismically active as regions near plate boundaries, large and damaging earthquakes do occur there. Furthermore, when these rare eastern U.S. earthquakes occur, the areas affected by them are much larger than for western U.S. earthquakes of the same magnitude. Thus, earthquakes represent at least a moderate hazard to East Coast cities, including New York City and adjacent areas of very high population density.

2011 Myanmar earthquake

The 2011 Burma earthquake occurred with a magnitude 6.9 Mw on 24 March. It had an epicenter in the eastern part of Shan State in Burma (Myanmar) with a hypocenter 10 km deep. It had two aftershocks, one of magnitude 4.8, another at magnitude 5.4, and two subsequent shocks at magnitude 5.0 and 6.2. The quake's epicentre was 70 miles (110 km) from the northern Thai city of Chiang Rai, north of Mae Sai and southeast of Kentung.

2011 Oklahoma earthquake

The 2011 Oklahoma earthquake was a 5.7 magnitude intraplate earthquake which occurred near Prague, Oklahoma on November 5 at 10:53 p.m. CDT in the U.S. state of Oklahoma. The epicenter of the earthquake was in the vicinity of several active wastewater injection wells. According to the United States Geological Survey (USGS), it was the most powerful earthquake ever recorded in Oklahoma; this record was surpassed by the 2016 Oklahoma earthquake. The previous record was a 5.5 magnitude earthquake that struck near the town of El Reno in 1952. The quake's epicenter was approximately 44 miles (71 km) east-northeast of Oklahoma City, near the town of Sparks and was felt in the neighboring states of Texas, Arkansas, Kansas and Missouri and even as far away as Tennessee and Wisconsin. The quake followed several minor quakes earlier in the day, including a 4.7 magnitude foreshock. The quake had a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale in the area closest to the epicenter. Numerous aftershocks were detected after the main quake, with a few registering at 4.0 magnitude.

Oklahoma earthquake swarms (2009–present)

The 2009–20 Oklahoma earthquake swarms are a series of human activity-induced earthquakes affecting central Oklahoma, southern Kansas, northern Texas. Beginning in 2009, the frequency of earthquakes in the U.S. state of Oklahoma rapidly increased from an average of fewer than two 3.0+ magnitude earthquakes per year since 1978 to hundreds each year in the 2014–17 period. Thousands of earthquakes have occurred in Oklahoma and surrounding areas in southern Kansas and North Texas since 2009. Scientific studies attribute the rise in earthquakes to the disposal of wastewater produced during oil extraction that has been injected more deeply into the ground.

2018 Hawaii earthquake

On May 4, 2018, an earthquake with a magnitude of Mw 6.9 struck Hawaii island in the Hawaii archipelago at around 12:33 p.m. local time. The earthquake's epicenter was near the south flank of Kīlauea, which has been the site of seismic and volcanic activity since late April of that year. According to the United States Geological Survey the quake was related to the new lava outbreaks at the volcano, and it resulted in the Hilina Slump moving about two feet. It was the largest earthquake to affect Hawaii since the 1975 earthquake, which affected the same region, killing two people and injuring another 28.

2018 Southern Appalachian earthquake

An earthquake measuring 4.4 MW on the moment magnitude scale struck 6.8 miles (10.9 km) north-northeast of Decatur, Tennessee in the eastern part of the state on December 12, 2018 at 4:14 a.m. Eastern Standard Time. The earthquake occurred at a depth of 9.0 kilometres (5.6 mi). The earthquake occurred along the Eastern Tennessee Seismic Zone (ETSZ), a geographic band stretching from northeastern Alabama to southwestern Virginia that is subject to frequent small earthquakes. The earthquake was felt throughout the Southeast, primarily in eastern Tennessee and the Atlanta metropolitan area. While relatively minor, this earthquake was the largest to occur on the ETSZ since the 4.6 MW 2003 Alabama earthquake, the third largest to have been recorded in the area, becoming the fourth largest earthquake recorded in the region. Robert Sanders from the U.S. Geological Survey told WSB-TV that aftershocks would be possible throughout the day after the quake.

2020 Central Idaho earthquake

The 2020 Central Idaho earthquake occurred on March 31, 2020, at 5:52 PM MDT in the Western United States, near Ruffneck Peak in the Sawtooth Mountains in Central Idaho, 72 miles (116 km) northeast of Boise, Idaho and 19 miles (31 km) northwest of Stanley, Idaho.

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Further reading