Mississippi Blues: The earthquakes of New Madrid

Source:  University of Memphis

Source: University of Memphis

The Mississippi valley had once been densely inhabited, but it was so no longer. The Indian cultures had been decimated by disease; their lands were emptied and their villages deserted. The area had just become US property, and American settlers were moving in but it was still early days, here on the western frontier, in 1811. To the north, St Louis was home to some 1200 people; to the south, Memphis did not yet exist: its area remained part of the Chickasaw nation, themselves fairly recent (15th century) migrants. Yet the river was already heavily trafficked and boats were frequent; the age of the steamboat was only days away. Turning one of the many bends of the river, the boats would pass the town of New Madrid. It consisted of some 400 log cabins and two brick buildings, and was similar in size to St Louis. The name recalled a checkered origin; the town had been settled during the Spanish period in 1778, the Spanish traded it to the French in 1800 (in secret), who sold it on to the US in 1803 as part of the Louisiana purchase, in a fairly broad definition of Louisiana which extended from the Gulf to beyond the Dakotas, even covering a small part of what is now Canada. The trade included the land with all its beauty and faults, as well as the population, Indian, white migrants, and black people (some slaves, some free) alike. The town would finally end up in Missouri. New Madrid still exists, and is now a town of 8000 people, having been far outgrown by both St Louis and Memphis. But it is not old New Madrid: that lies lost underneath the river. The current town dates from 1812, a new New Madrid, risen from the ruins of a disastrous year.

The earthquakes began on Monday, 16 Dec, 1811, 2:15 am, on a dark and moonless – but not stormy – night. The first shock lasted one to two minutes. People on boats on the river said the shock lasted about 40 seconds – people on land felt it for longer. A second, less severe shock followed 30 minutes later, one of a very large number of aftershocks. Another strong quake happened around 6:30, and around 7:15 there was a very strong quake which in places may even have exceeded the first; in one report the last event was violent but lasted only about 20 seconds and was followed by a large spout of water rising from the river to a height of 6 meters. At this time the land was seen to move in foot-high waves, coming from the west.

After the first disaster

After the first disaster

New Madrid was left badly damaged and many houses had lost their roofs and chimneys. But the town was not destroyed. Further south, the damage was worse. The day after the earthquake, on Dec 17, the very first steam boat arrived on its inaugural journey. Seeing the devastation, the New Orleans did not stop but continued its journey south. Many accused this new-fangled and dubious invention of having caused the earthquake!

The numerous aftershocks slowly decreased over the weeks. But another strong earthquake hit on 23 Jan 1812. Two riverside villages were flooded by the Mississippi: Little Prairie and Point Pleasant – luckily the first town had been abandoned in December, its people having fled to New Madrid finally arriving on Christmas Eve, leaving a single infirm (and black) person behind, and the population of the second town, about 100, managed to escape on foot, in the dark. Again the aftershocks came and declined. A lesser earthquake came on 4 February, and the final destructive one, possibly the strongest, happened on 7 February, at 3 am, lasting 90 seconds. This time the epicentre was close to New Madrid, and this did destroy the town. The seven weeks of shocks left widespread devastation. The quakes were felt over much of the young nation, and even shook the White House. Casualties were probably light, due to the sparse population. Most people who died had been on the river. Casualties among the Indian villagers may have been higher but these were not recorded.

The Mississippi plains had now changed beyond recognition, so much so that captains lost their bearings. Many islands in the river had sunk, disappeared, or changed in outline. On one ex-island only the top of the trees were above the river. Land slides had eroded the banks of the river. Numerous little mounds of sand dotted the previously featureless plains. Trees had snapped or toppled and numerous floating trees obstructed the river. Large areas of land had turned to water, a result of liquefaction, which downstream also greatly increased the flow rate of the Mississippi. In other places the land had been thrown upward. The February quake dammed the river and famously caused the Mississippi to flow backwards for a few hours. New rapids made the river almost impassable for a while, until erosion had removed the new obstacles of clay. New lakes formed – and some of these still exist.

News of the disaster slowly made it to the populated areas, where it was viewed as sensational but unimportant. The headlines, like yesterday’s news, were quickly forgotten. This was after all the frontier, where strange things happened but where few people went – and fewer came back. The New Madrid earthquakes became a legend rather than actual history; and like legends, the telling grew in exaggeration and decreased in believability. That has continued until today, even now that science has rediscovered the event. Popular writings try to outdo each other in describing what happened. The size became an 8+, than an 8.5, in one book even an 8.8. It could have split the US. Who cared? It wasn’t real history anyway. The middle ground between denial and doom was lost, the kernel of truth overgrown like badly written software. Let’s see whether we can dig out the hidden truth.

Eyewitness and local reports

Many reports were published in newspapers and magazines, over the days, weeks and years following the events. Some were detailed, some provided overwhelming impressions but less factual information, and some reported sensational second-hand stories. A few of the reports give wrong dates; the accuracy is not always beyond doubt.

Godfrey Lesieur is one of the better examples. He was in New Madrid on that December day but only wrote down his recollections 50 years later. Although his recollected dates were not fully correct, details of his report agree well with others:

The first shock of the earthquakes was on 2am o’clock on Dec 17, 1811, and was very hard, shaking down log houses, chimneys, etc. It was followed at short intervals, half to one hour apart, by comparatively slight shocks until about seven o’clock in the morning, when a rumbling noise was heard apparently in the west resembling and not unlike distant thunder. In an instant the earth began to shake and toter to such a degree that no persons were able to stand or walk. This lasted perhaps for one minute, and at this juncture the earth was observed to be as it were rolling in waves of a few feet in height, with visible depressions in between. By and by these waves or swells were seen to burst, throwing up large volumes of water, sand and a
species of charcoal, some of which were covered in part with a substance of which, by its peculiar odor was thought to be sulphur. When these swells bursted wide and long fissures were left running north and south parallel with each other for miles.

[…] A very large extent of country on either side of Little River, also on both sides of the St. Francois river, in this state and Arkansas, and on the Reel Foot Bayou in Tennessee was sunk below its former elevation about ten feet, thus rendering that section of country entirely unfit for cultivation. It is a remarkable fact and worthy of notice that so few casualties occurred, among the citizens there were but two deaths, both victims being women: Mrs. La Font died from fright and Mrs. Jarvis received injury from the fall of a cabin log from which she died.

[…] In many conversations with the old men of several tribes, Shawness, Delawares, and Cherokees, all said that they had no traditionary account that earthquakes had ever visited the country before.

[…] The water thrown up during the eruption of the “land waves” was luke warm, so warm indeed as to produce no chilly sensation while wading and swimming through it.

A woodcut depicting the New Madrid collapses

A woodcut depicting the New Madrid collapses

Mathias Speed was on the river during the final, February 7 quake. He wrote the following for the Bardstown Repository (1812):

About 3 o’clock, on the morning of the 7th, we were waked by the violent agitation of the boat, attended with a noise more tremendous and terrific than I can describe or any one can conceive, who was not present or near to such a scene. The constant discharge of heavy cannon might give some idea of the noise for loudness, but this was infinitely more terrible, an account of its appearing to be subterraneous.

As soon as we waked we discovered that the bar to which we were tied was sinking, we cut loose and moved our boats for the middle of the river. After getting out so far as to be out of danger from the trees which were falling in from the bank – the swells in the river was so great as to threaten the sinking of the boat every moment.

We stopped the outholes with blankets to keep out the water – after remaining in this situation for some time, we perceived a light in the shore which we had left – (we having a lighted candle in a lantern on our boat,) were hailed and advised to land, which we attempted to do, but could not effect it, finding the banks and trees still falling in.

[…] We landed at New Madrid about breakfast time without having experienced any injury – The appearance of the town, and the situation of the inhabitants, were such as to afford but little relief to our minds. The former elevation of the bank on which the town stood was estimated by the inhabitants at about 25 feet above common water; when we reached it the elevation was only about 12 or 13 feet –

There was scarcely a house left entire – some wholly prostrated, others unroofed and not a chimney standing – the people all having deserted their habitations, were in camps and tents back of the town, and their little watercrafts, such as skiffs, boats and canoes, handed out of the water to their camps, that they might be ready in case the country should sink.

I remained at New Madrid from the 7th till the 12th, during which time I think shocks of earthquakes were experienced every 15 or 20 minutes- those shocks were all attended with a rumbling noise, resembling distant thunder from the southwest, varying in report according to the force of the shock. When I left the place, the surface of the earth was very little, if any, above the tops of the boats in the river.

There was one boat coming down on the same morning I landed; when they came in sight of the falls, the crew were so frightened at the prospect, that they abandoned their boat and made for the island in their canoe- two were left on the island, and two made for the west bank in the canoe – about the time of their landing, they saw that the island was violently convulsed – one of the men on the island threw himself into the river to save himself by swimming – one of the men from the shore met him with the canoe and saved him. –

This man gave such an account of the convulsion of the island, that neither of the three dared to venture back for the remaining man. The three men reached New Madrid by land.

The man remained on the Island from Friday morning until Sunday evening, when he was taken off by a canoe sent from a boat coming down. I was several days in company with this man – he stated that during his stay in the island, there were frequent eruptions, in which sand and stone, coal and water were thrown up.

The violent agitation of the ground was such at one time as induced him to hold to a tree to support himself; the earth gave way at the place, and he with the tree sunk down, and he got wounded in the fall. – The fissure was so deep as to put it out of his power to get out at that place – he made his way along the fissure until a sloping slide offered him an opportunity of crawling out.

He states that frequent lights appeared – that in one instance, after one of the explosions near where he stood, he approached the hole from which the coal and land had been thrown up, which was now filled with water, and on putting his hand into it he found it was warm.

One of the Mississippi islands involved in the disaster, island number 10 near New Madrid, later became the site of a battle in the American civil war. The island has since disappeared

One of the Mississippi islands involved in the disaster, island number 10 near New Madrid, later became the site of a battle in the American civil war. The island has since disappeared

William Pierce, also traveling on the river, provided a good description of the size of the area affected by the 16 December quake (although it would be easier if more of the names he described still existed on the maps!)

At New Madrid, 70 miles from the influence of the Ohio, and on the right hand, the utmost consternation prevailed among the inhabitants; confusion, terror and uproar presided; those in the town were running for refuge to the country, whilst those in the country fled with like purpose towards the town. I am happy, however, to observe, that no material injury has been sustained.

At the Little Prairie, 103 miles from the same point, the shocks appear to have been more violent, and were attended with severe apprehensions. The town was deserted by its inhabitants, and not a single person was left but an old negro man, probably too infirm to fly: everyone appeared to consider the woods and hills most safe, and in these confidence was reposed. Distressing, however, as are the outlines of such a picture, the latest accounts are not calculated to increase apprehensions. Several chimnies were destroyed, and much land sunk, no lives however have been lost.

A little below Bayou River, 103 miles from the same point, and 130 miles from the spot where we lay, the ruin begins extensive and general.

At Long Reach, 146 miles, there is one continued forest of roots and trees, which have been ejected from the bed of the river.

At the near Flour Island, 174 miles, the destruction has been very great, and the impediments in the river much increased.

At the Devil’s Race ground, 193 miles, an immense number of very large trees have been thrown up, and the river is nearly impassible. The Devil’s Elbow, 214 miles, is in the same predicament; below this the ruin is much less, and indeed no material traces of the earthquake are discoverable.

Some other reports need to be read with some degree of skepticism. A report from North Carolina mentions a second-hand story of tremendous noises in the mountains hours before the big shock, accompanied by flashes of fire issuing from the side of the mountains, ending with a loud snap or crackle. The credibility of this story is not clear. Reports that church bells rang in Charlestown, Boston, are not supported by newspapers published in Boston itself. They may be confused with Charleston, South Carolina – much closer to the epicentre, and in an area where residents reported feeling like they were adrift on rough oceans during the quakes.

There are no good reports on how the earthquake affected the Indian population. The Shawnee chief Tecumseh had just failed to unify the various tribes against the settlers, and in some ways he was seen as a prophet of the destruction. Did it change their culture, their philosophy, their politics? That wasn’t recorded – it wasn’t ‘American’ history.

Characteristics

The many reports allow the story to be pieced together. There were three main episodes of earthquakes, shown in the following table. Each consisted of one or more major events, with a large number of aftershocks.

 Sequence of the earthquakes, with approximate times and magnitude. From The Enigma of the New Madrid Earthquakes of 1811-1812, A. Johnston, & E. Schweig, Annual Review of Earth and Planetary Sciences, Volume 24, pp. 339-384 (1996).  The magnitudes here have since been revised down, although his remains uncertain.

Sequence of the earthquakes, with approximate times and magnitude. From The Enigma of the New Madrid Earthquakes of 1811-1812, A. Johnston, & E. Schweig, Annual Review of Earth and Planetary Sciences, Volume 24, pp. 339-384 (1996). The magnitudes here have since been revised down, although this remains uncertain.

The most detailed information came from people who were on the river. The Mississippi was already a major transport route; in contrast, the local population was sparse and lived in isolated settlements. The lack of detailed reports on the January quakes is related to this. At that time, the upper Mississippi was fully frozen and all river transport had ceased. The lack of detail does not mean this was a lesser event, but it did affect fewer people. The December quakes led to many landslides along the river, and toppled many trees. In addition, there were a number of islands within the river and these were badly affected, in some cases fully submerging. But only in the February earthquake did new rapids form. This final earthquake had a dip-slip component which pushed up the land, and crossed the river in three places. The fault causing the December quake either was pure strike-slip, or did not cross the river.

A significant point is the widespread liquefaction. Water came up everywhere, in places spouting from the ground, deep enough to swim in. Often it also brought up sand, forming new sand hills. The sand blows (also called sand volcanoes) and sand dikes could be hundreds of meters long – one covered the abandoned town of Little Prairie to a depth of 2 feet. The shape of the land had changed dramatically after the earthquakes. The cartoon below, from USGS, shows how these sand blows worked.

Source: USGS.  Liquefaction and sand blows

Source: USGS. Liquefaction and sand blows

An ancient sand blow vaguely visible in a plowed field near New Madrid

An ancient sand blow vaguely visible in a plowed field near New Madrid

Liquefaction is a common hazard of earthquakes. It happens when the soil is loose and granular, saturated with water, and subjected to strong shaking. The shaking separates the granules from each other, and this causes the saturated soil to loose its strength and expel some of its integral water content. Suddenly the soil flows like a liquid. It can happen during or immediately after the earthquake, and may be seen hundreds of kilometer from the epicentre. Conditions in the Mississippi valley, with its sediments and high water table, were ideal for this. A famous example of liquefaction (not earthquake related) is the Norwegian disaster of 1978: see this program. It gives a good idea how devastating and dangerous it can be.

Why was the water luke warm? There was no obvious source of heat – no baby volcanics here. But remember that it was winter, and the temperature was around 5 C. The Mississippi would have been rather chilly. The water that came up from the ground wasn’t ground water. It had been an integral part of the soil and clay, and was released at depth by the shaking. It would have had the same temperature as the soil. At a depth of a meter, the soil approaches the average temperature over the year, which in this area is 17 C. As long as the water came from soil deeper than this, it would have been at this temperature: it would feel comfortable, but not hot, to people accustomed to winter temperatures. There are some report of much hotter water, in one report at 142 F, but that was in North Carolina, far from the epicentre, where liquefaction did not occur. This was water released from local hot springs. The report of ‘warm’ water after the February earthquake can be understood by the fact that the Mississippi had recently been frozen, upstream. It would have been very cold water, and in contrast water at 17C would have felt shockingly warm!

A number of the reports mention the haze (or darkness) and sulphurous smell. The haze was no doubt due to dust shaken into the air. The cause of the smell is less obvious. In the old sand boils, driven to surface from meters deep, you can find small nodules, akin to hardened asphalt. Scratch them and they smell like petrol. Organic matter, buried below the sediment in anoxic decay can smell pretty bad! The lights seen by the man trapped on the island sound like Will-o’-the-wisps, also called Jack-o’-lantern – swamp lights, related to escaping methane and other volatile hydrocarbons.

The area worst affected in the December quakes ran from New Madrid to a place called Flour Island. The name Flour still exists on the map, and is about 40 km north of Memphis. South of Flour Island, there was little destruction; north, the river was almost impassable due to debris and other hazards (including captains getting lost as the river bed had changed so much!). This makes the total length (as the crow flies) of the quake zone roughly 80 kilometer.

Magnitudes

The magnitudes of the earthquakes are very poorly known. Various papers have suggested values of low M8’s. But recently, estimates have come down, and mid M7’s is now more commonly quoted. Given the length of the fault system involved, even this may be high. The re-assignment of the church bells of Boston to Charleston has also drastically reduced the required magnitude. In 2010, Susan Hough argued that the shaking maps are consistent with about M7.0. This is a dramatic reduction, but it brings the earthquakes within range of other intraplate tectonics.

Using an approximate relation between the area of the rupture (length times depth, in square kilometer) and the magnitude of an earthquake, M = 4.07+0.98*log(Area), and taking the length as 100 km (an overestimate) and depth as 10 km (perhaps an underestimate), the earthquake size comes out as M = 7.0 . It is difficult to get much more out of the rupture zone. This provides another argument against the very high older estimates in excess of M8: the New Madrid events have most likely been around M7.

Many web sites state that the New Madrid earthquakes were among the largest earthquakes to hit the US in recorded history. This is overstating the case. There were large and destructive, but there is no evidence they were as huge as that.

An American fault

The local people all confirmed that there had been no earthquakes felt before these events. People from the local tribes also had no traditions of earthquakes in the area. It seemed a tectonic dead water. The Mississippi brought enough action for anyone, in its meandering and constant threat of changing its channel. But in fact the Mississippi has a hidden history. It hijacked a much older valley, which does have a tectonic origin.

For this, we need to go back a long way. Before the Atlantic Ocean, before Pangea, there was the Iapetus Ocean. Its closure formed the Appalachian mountains. But the Iapetus also had a beginning. Before it formed, Europe and America were linked in another supercontinent. The inevitable splitting involved rifting, and one of those rifts started but never finished. It became a failed rift. One or two arms of the triple junction started an ocean, but this arm did not. Magma intruded and solidified (but did not make it to the surface). Much, much later, marine and river sediment filled in much of the depression. This is the Mississippi embayment; New Madrid is in its northern part. The depression is still visible, even if deeply filled in: it is now called the Reelfoot rift, a wide valley which the Mississippi has claimed for its own floodplain.

Earthquakes since 2001, with M>2.5, taken from the USGS, clearly show the faults at work.

Earthquakes since 2001, with M>2.5, taken from the USGS, clearly show the faults at work. The Blytheville-Tiptondale section is the Cottonwood Grove. From Dyersburg to New Madrid is the Reelfoot thrust.

Recently (geologically speaking), the area has re-activated: new faults have developed. The figure, taken from USGS, plots moderate earthquakes (M>2.5) since 2001. These clearly delineate a fault. In fact, three fault segments are visible, one from Blytheville to Tiptonville (called Cottonwood Grove), a perpendicular one from Dyersburg running north-northwest (the west-dipping Reelfoot thrust), and a less clear segment from New Madrid northeast-ward. The first and last segments may trace the same fault, but with an offset; the second, perpendicular segment appears to be the fault doing the offsetting. This is a complex region! The complexity, the short length, and the limited offset all suggest this fault system is still young. It seems two or all three segments ruptured separately in 1811/12, giving rise to the earthquake sequence. The perpendicular fault is visible on the surface as the Reelfoot scarp, a step-change of as much as 8 meter, which dates in part from the 1811/12 events.

Recent GPS measurements confirm the faulty nature. They show right-lateral slip of 5 mm per year. That would allow for 5 meter of slip every 1000 year, and this should be roughly the recurrence time. Is there any evidence for past earthquakes here? In fact, there is, but you have to look hard. The most obvious remnant of the 1811/12 earthquakes were the numerous sand hills. But some of the sandy deposits have Indian artefacts above them. As the Indians had largely left the area by 1811, these artefacts must predate the earthquake, and therefore those sand deposits must also be older than 1811. It seems there must have been very similar earthquakes here before. The latest one before 1811 has been dated to around 1450 A.D., and earlier ones to 900 A.D., 300 AD., and 2350 BC, give or take a century or so. All of these were outside of the Indian oral tradition. For a recurrence time of 500 year, the slip of the 1811/12 quakes would have been around 2.5 meter.

The total offset between the two fault fragments at New Madrid is about 20 km. Presumably these segments where originally one fault, which was split in two; the offset gives an age of 4 million year. For comparison, along the San Andreas fault there has been over 100 km of cumulative slip. New Madrid indeed is a young tear in a much older land.

Source: Geolurking. Click for full resolution.

Source: Geolurking. Click for full resolution.

The image, kindly created by Geolurking, shows some of the features of the region. The earthquake was one of the usual ones near New Madrid, a recent aftershock of 1811. The fault lines are from USGS shapefiles, and the pluton shapes are from several different papers (green hatched shapes). The light blue dashed line is the extent of the Mississippi embayment. The red concentric circle in Tennessee is Wells Creek crater. The three faults which combined to destroy New Madrid can easily be recognized.

Giving way

There were four main shocks in the sequence, and incessant aftershocks.

The first shock, at 2:15am Dec 16, was a major strike-slip on the Cottonwood Grove, with a displacement of perhaps 3-4 meter. During the morning quake on that day, 5 hours later, the land waves came to New Madrid from the west as stated by Lesieur. One model has it as a small slip on the Reelfoot fault but this seems inconsistent with the direction of the surface waves. However, there is also a small extension of the Reelfoot fault running to the west from its end point, towards Malden, and this might be consistent with the report from Lesieur. The 7 February earthquake was the one that caused the rapids to form in the river. Therefore, this was the major thrust, on the Reelfoot fault. The aftershocks from this event came to New Madrid from the southwest.The three quakes occurred on three adjacent faults, curving round poor New Madrid.

The question of Illinois

The small star shows a possible epicentre of the 23 Jan 1812 event; the large star shows the location of the 1968 Southern Illinois earthquake. Black circles correspond to locations where liquefaction was documented during the 1811–1812 sequence. The easternmost and largest circle identifies the location of the White County, Illinois, event, the account of which describes substantial liquefaction as well as surface cracking From Mueller et al, Nature, 429, 284 (2004)

Estimated shaking maps, and possible location for the 23 Jan 1812 earthquake. Image from Mueller et al, Nature, 429, 284 (2004). Click on the image for higher resolution.

This leaves the enigmatic 23 January event. Models have difficulty reproducing it: there isn’t an obvious area which could have caused it. One suggestion is that this event wasn’t near New Madrid at all. There is another potential area of activity 200 kilometers away, in Illinois, where small earthquakes are frequent. A local land owner, Yearby Land, experienced the 1811/1812 quakes as a boy of 9. Many decades later his stories were passed on by his nephew. Land told how the ground would shake and then rock and roll in long waves. After a short quiet spell, there would be another shock and roll. In these long continued rollings, the tall trees would weave their tops together, interlock their branches, then part and fly back the other way, and when they did this the blossom ends of the limbs would pop like whip lashes; and the ground was covered with broken stuff. About two miles east of his father’s house, a big crack was made in the ground, and you could not see to the bottom of it. The ground on its south side had sunk down about two feet. By 1858 this slope (at 38.07° N, 88.11° W) could still be traced over a length of two miles. The slope is reminiscent of a fault, and has led to suggestions that this was the epicentre of the 23 Jan 1812 earthquake. In support of this, there is evidence on the ground for liquefaction and sand volcanoes there too. Land said that piles and piles of pure, snow white sand were heaved up from the size of a bee-gum too three or four wagon loads.

Image: The small star shows a possible epicentre of the 23 Jan 1812 event; the large star shows the location of the 1968 Southern Illinois earthquake. Black circles correspond to locations where liquefaction was documented during the 1811–1812 sequence. The easternmost and largest circle identifies the location of the White County, Illinois, event, the account of which describes substantial liquefaction as well as surface cracking.

An analysis of the shaking reports of this quake finds some support for this location, as shown in the image. They suggests that the 23rd Jan earthquake, which they estimated at M6.8, may have occurred on an east-west oriented fault, triggered by stress from the first Mew Madrid earthquake. This can not be considered conclusive. We do not know whether the crack traced a fault or a land slip, and sand boils can occur some distance away from the epicentre. This is a known area of earthquake activity, but the quakes are quite wide distributed and at low level compared to New Madrid. Also, the lack of report from further south may just be from the lack of river traffic rather than a deficit in shaking. More research is definitely needed.

Here and now

New Madrid is a damaged area in a big land. What are the implications? Almost depopulated in 1811, now as many as 4 million people live within the New Madrid Seismic Zone. How safe are they?

The recurrence times of the earthquakes are such that a major event within the next century on the New Madrid fault is less likely. A smaller earthquake could still be damaging, though. There were strong aftershocks in the 1850’s and 1890’s, and there are still numerous small tremors, typically a few each week. The chances of an earthquake up to M6 over the next 50 years are considerable. Such an earthquake could do significant damage. The I-55 connecting Memphis and St Louis passes through the main liquefaction area and could quickly be destroyed. Three major pipelines pass through the region. And the earthquake resilience of buildings in Memphis has never been tested for real! One day it may be.

But there is an even deeper issue. What did re-activate the fault, and is this the only area that has been thus affected? Or are there similar re-activated faults nearby that we don’t know about just because they have not failed in living memory? As to the first question, it has been suggested that stress building up in the continent (there is always stress in the US) can re-activate an ancient line of weakness, and do so only over a small region. Once it gives, the stress may than be transferred to another fault fragment. For the second question, soundings of the Mississippi basin over the past decade have revealed that there are such old faults also further south, which were active perhaps 100 million year ago. But in places, the ruptures from these faults extend into the top sediment, suggesting events within the last 10,000 year. These are the unknown faults which could do a new New Madrid.

Both New Madrid and Illinois are regions of significant on-going micro-seismicity. This is interpreted as aftershocks from the 1811/12 earthquakes, rather than precursors to the next event. But remember there were no felt earthquakes for many years prior to the 1811 shock. Before the event, the fault went silent. This is important: we need to hear the silence. The silent faults need to be mapped, especially in regions where stress may be building up. Risk management begins with recognizing the dangers.

Perhaps one day, another town with no tectonic history will give its name to an unforeseen event, moving from a small locality to historic significance. Thus is the danger of silence.

The Louisiana purchase transferred a land with hidden faults. Perhaps the US should have paid for the extended warranty.

References

Eye witness accounts
River travelers
More eyewitnesses
Science of the New Madrid Seismic Zone
Yearby Land

Arch Johnston and Eugene Schweig, 1996: The enigma of the New Madrid earthquakes of 1811–1812. Annual Review of Earth and Planetary Sciences Vol.24, pp.339-384
Karl Mueller, Susan Hough & Roger Bilham, 2004: Analysing the 1811–1812 New Madrid earthquakes with recent instrumentally recorded aftershocks. Nature, 429, 284-288 (paywalled)

A sign in need of an update

A sign perhaps in need of an update

Updated 11 March 2017, to include Geolurking plot of the Mississippi geology

Albert

76 thoughts on “Mississippi Blues: The earthquakes of New Madrid

  1. I know that southern Illinois has oil deposits. A friend of the family gets a dividend every month from a well they own in west Frankfort.

    • Ominously, from the post:
      ” small nodules, akin to hardened asphalt. Scratch them and they smell like petrol. Organic matter, buried below the sediment in anoxic decay can smell pretty bad! The lights seen by the man trapped on the island sound like Will-o’-the-wisps, also called Jack-o’-lantern – swamp lights, related to escaping methane and other volatile hydrocarbons.”

      If I was a fracker I’d be rubbing my hands in glee at that sort of evidence

      • If you were a fracker here, you might also drill into an abandoned coal mine. Many of them are undergoing subsistence causing structural problems in unwanted places. I researched mine locations when I bought my house in 2011 to see if I needed “mine insurance”. No mine under me! I do have earthquake insurance though. Too close to New Madrid and Wabash Valley faults.

  2. I live in the Charleston (SC) area – Summerville, actually – and we have a similar history; the earthquake of 1886. Many downtown Charleston period buildings have earthquake bolts that assist in holding the buildings together (not sure how effective they are, but they are a unique architectural feature of the area) that were installed just after the “The Great Quake” left the region in ruins. We still have earthquakes frequently, mostly in the 1.x or 2.x, but given that most epicenters are centered on Summerville and my relative proximity to them, I have felt a few of the 3.4’s and 3.5’s.

    This area is still “littered” with the old sandblows, as sand is the primary make up of our soil. Most of the Lowcountry is marsh, swamp, or some reclaimed version of the two, so the water table is never very far below your feet here. We found that out the hard way for two consecutive Octobers now – Hurricane Joaquin just after the Blood Moon Eclipse in 2015 and last year with Hurricane Matthew – any rains that last longer than a few days just runs out of places to go and Mother Earth reclaims her reclaimed swamp/marsh.

    Most new structures are required to be quake compliant in some measure, but there are a many older structures here that just wouldn’t survive a 5 or 6, and too many people would not survive as a result. Like many a volcano, these quakes are not well understood, not well monitored, and not well studied; this is going to bite us one day.

  3. Brilliant article, thank you. This is the most vivid account I have ever read! The eye witness reports are amazing. Just a thought – The heat of the water from the liquefaction puts me in mind of reports from Banda Aceh in 2004 when those caught in the tsunami said that the water was hot and black. Could it be friction causing the heat? Or does it come from the depth of the rupture, from deeper aquifers?

    • My guess is that it’s from the location of the water before it began it’s drive to the surface. The geothermal gradient is still high enough here to have water of higher temperature not that deep below the surface. I don’t have the current plot, but one that I made a while ago shows that the gradient is higher in the Louisiana area.

      Description/Abstract: A statistical analysis of bottom-hole temperatures from oil and gas wells in the northern Mississippi embayment suggests that the geothermal gradient below a depth of 1 km is low (22.2°C/km) and for the New Madrid seismic zone, it is even lower (15.7°C/km).”

      Warning: Dead Link → http://www.osti.gov/geothermal/product.biblio.jsp?osti_id=6559807

      Geothermal gradients in Mississippi embayment” Staub, W.P. ; Treat, N.L. (1983) Sep 01 OSTI

    • The friction can’t have caused the warm water. You can’t warm water by shaking it – try it. Water takes too much energy to warm up. You can get warm water from geothermal resources, as Lurking mentions, but those are very deep, too deep to be released by the earthquake. The luke-warm water in the New Madrid earthquake was normal water from a few meters down, at an average temperature for its depth. It felt warm because it was winter, and in this days winter meant living in cold conditions all the time. A warm bath was not normal.

      I have looked for references for your mention that the Banda Aceh tsunami was ‘hot and black’. Big tsunami waves look dark: they carry a lot of debris. Water doesn’t have much colour by itself, but takes on the colour of the light it reflects (in my sailing days we looked at the colour of the water to see whether rain was near – it saved the bother of peeking up). A layer of floating debris means no light enters the water, so it appears dark or grey – and this term is used in descriptions of the tsunami waves. I did not find a single mention of hot water in the tsunami. National Geographic called it ‘warm’ water, but that makes sense as the tropical ocean is warm. There are a lot of references to ‘boiling water’ to describe the extreme turbulence. It sound to me that either some reporter confused this with ‘hot’, or upgraded ‘warm’ to ‘hot’.

      • Its possible that roiling water became the literary boiling water. Bubbles released through standing water can make it seem to boil. If there are a lot of bubbles, visually, it could look the same, especially to someone terrified beyond belief. Also, water boiling in a pot would probably have been the only experience they had of bubbles coming out of water. As for the source, well, even saturated soil can contain a lot of gasses. As liquefaction takes place, formerly solid ground becomes fairly liquid.

        • Surfers often talk about the water “boiling ” just in front of a wave as it gets sucked off a reef to be subsumed into the wave. This is caused by the water being pulled around and over (increasingly) shallow rocks. Understandably, it’s taken as a warning sign that you definitely don’t want to wipe out right at THAT spot.
          Excellent article. I’ve always been curious about this particular sequence of events. And having spent a considerable amount of time looking into the UK’s “Great Flood” of 1606/7, I fully appreciate the difficulty of making sense of historic eye witness reports.

          • When I suggested friction I was thinking of the rocks rupturing, generating heat, which then may have passed into the water. The New Madrid fault had reports of oil burning spontaneously in places, perhaps generated by the heat friction from the rocks? Just a puzzle which isn’t yet solved….

            Rescued from the dungeon of Spamdovia… – Admin

  4. Side note. (I had a lot of these tossed at Albert while he was prepping his article, it’s a wonder he was able to wade through my distractions to come up with such a fantastic article.)

    The Missouri Bootheel, that portion that extends south of 36°30’ North, has numerous accounts about how it wound up as part of Missouri. One version, which makes sense to me, is that a lot of the distressed land from the New Madrid quake was bought up by an investor. When Missouri was preparing to submit it’s application for statehood, the new owner of the land petitioned the Missouri legislature for inclusion in it’s boundaries in it’s application. I wasn’t there, but it seems like the perfect scenario for payoffs and favors. Being in a State would have jacked up the property value quite a bit.

    NOTE: I am not saying that is what happened. It’s just idle speculation on my part.

    More On topic musings. Thebes Gap is a location where the Mississippi makes a turn into the eastern lowlands. (East of Crowley’s Ridge). Before seismic events opened that cut, the river flowed down the Western lowlands (West of Crowley’s Ridge). Crowley’s Ridge is a manifestation of the stresses and motion of the fault system.

    And another side note. Some papers I’ve read point to 0.6 g shaking as being sufficient to destroy most modern interstate style bridges. (60% g). The brick and mortar structures that feel that level of shaking are not going to fare well at all. (Hello Memphis). This level of shaking WILL happen. Eventually. WHEN it will happen is anybodies guess. It could be tomorrow, it could be in 500 years. Either way it’s gonna be a mess.

    Albert noted that plutons underlie the region. I have a plot from a couple of years ago that map them out. Rather than try to reconstruct that plot, it’s easier to go to the source material. Specifically, figure 1 on Page 8.

    Gravity of the New Madrid Seismic Zone
    A Preliminary Study

    By V.E. Langenheim

    U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1538-L

    • Note: There was a period in American History where the cool thing was to name places after other historic places. “Thebes” Gap is a good example. As is “Bagdad” Florida. (Yeah, I know it’s misspelled, but Santa Rosa county has a lot of that.) “Mulat” Rd for example. (instead of Mullet) At some point you just say screw it and embrace the concept of Redneck. They even have a “Billy Bob” Lane. It’s just south of “Punjob” Rd.

    • I have updated the post to include one of your images, showing the plutons

  5. Great article, Albert. If the January 23rd event happened in Illinois, that would be the Wabash Valley Seismic Zone. I live in southern Illinois about 70 miles mostly west and a little south (as the crow flies) from St. Louis. There was a 5.2 quake from that fault in 2008 that rocked me out of bed about 3:30 am. and was very noisy. Even after it stopped, the glass in the storm door vibrated for a while. I can’t imagine how terrified the people were in 1811-1812. I don’t know about Memphis but St. Louis has installed concrete “earthquake” collars on the elevated interstate roads and reinforcements in some of the hospitals rooms.

    • Those collars are supposed to limit the spalling of the columns as the supported mass moves laterally with reference to the ground. This was the main failure mechanism for the freeways during the Loma Prieta quake in California. (Mw 6.9)

      • Odd hazard I had not thought of before. Re Loma Prieta: “The quake claimed one life in Watsonville, a driver who collided with panicked horses after they escaped their collapsed corral.

        Driving into a stampede is probably never a good idea, though in this case, the stampede came to him. A horse’s natural instinct is to run from danger, and they are built for the task. 72 kph is well within their performance envelope.

  6. As for the church-bells in Boston… dunno. This is the energy dissipation plot for the Central US for a Mag 8.0 level quake at New Madrid. In case you can’t read it. Red vert line – Memphis, Green, Charleston SC, Blue, Boston MA. MMI is the level of shaking. Boston MA would have been in the below MMI-3 range. “Many people do not recognize it as an earthquake.”

    • From the MMI-VII description: “Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse.”

    • Yes, you would need a BIG earthquake to ring the bells that far away. This report of Boston bells made the New Madrid quakes excessive. Moving the church bells closer to the epicentre helps a lot in understanding what really happened, and reduced the size to something more reasonable.

    • I can attest to the “Many people do not recognize…” part for a 3.x. The jolt is typically so short (measured in seconds) that you hear it more than feel it. It sounds like a trash truck dropping a dumpster from about 3 meters.

  7. I did wonder what would have happened had there been no New Madrid earthquakes. New Madrid was becoming quite a major settlement, capturing the shipping from the Ohio. I think there is a good chance there would now be no Memphis but instead the metropolis of New Madrid.

    • Could have changed history in really odd ways. Imagine these lyrics:

      “You ain’t nothin’ but a crawdad, boilin’ all the time…”

  8. Many GPS stations, both around Vatnajökul and Myrdalsjökul and both with the american and the european plates as references ar now moving up and east. Most likely a GPS error or????

  9. Salting, chances are big tomorrow they all bounce back in original position. Not sure wat causes this, but it happens quite often.

  10. Hawaii is complaining that the Midwest is getting all the attention. It has thrown up a cluster of small, deep earthquakes. See attached screenshot. Blue is shallow, the usual Mauna Loa & Kilauea activity. Blue/green and green is below 10km, again not unusual away from the summits. The yellow ones are 30-40km deep and that is quite a lot. They may come from a bit of sagging of the mountain, but that gives earthquakes distributed around the mountain, not normally in such a tight cluster. There are also some at that depth at Kilauea. Orange is below 40 km: they behave as you would expect. I wonder whether the inflation of Mauna Loa has caused a bit of motion on a deep fault.

    No danger of Mauna Loa sliding into the ocean – these quakes are much too deep for that..

    • 3dBulge shows it nicely on it’s graph. It’s a live graph so will change with time. Would someone capture & put it on here?

  11. A really good article, Albert. Including the historical statements of those who actually survived such a terrible event was gripping. I live in the southeastern area of Indiana near the Ohio River. I have felt a few tremors here over the years, so I appreciate all the info you have written.

  12. Bard has another star.

    Monday
    13.03.2017 02:40:19 64.671 -17.465 2.5 km 3.7 99.0 4.5 km NE of Bárðarbunga

    Info from IMO

  13. Great article Albert. Some legends have it that Shawnee Chief Tucumseh caused the earthquakes by stamping his foot on the ground 3 times when he was miffed at some locals declining to join his Confederacy. Care to calculate what stamping force would be required for a strategically stomped foot to release a magnitude 7 to 8 earthquake?

  14. The Volcanoes exhibition that’s on in Oxford this spring has been mentioned on here before but I popped in over the weekend and really enjoyed it, so I thought I’d post this reminder.

    I couldn’t stay for long (must go back) and the exhibition focusses mainly on volcanoes as depicted in books/print media, but amongst the delights on display, the Eruption Chaser suit will please children of all ages, there are some wonderful ?C18th drawings of Vesuvius (in astonishing cross-section), there’s some terrific C17th drawings of sea monsters off the coast of Iceland, and there’s a 15th century copy of Pliny’s account of the (eponymous) eruption of Vesuvius.

    http://www.bodleian.ox.ac.uk/whatson/whats-on/upcoming-events/2017/feb/volcanoes

  15. Bogoslof is unrecognizable, as I guess is normal after its eruptions. There is a large and liquid crater, formed from the explosions, with a crater wall which is rather thin in some directions and is likely to break to the north where a new vent has started. But the surroundings is now very shallow with al the ejecta, so a minor change in levels can change the appearance dramatically. The returning seals and puffins will have a shock and may want to wait until next year!

  16. It looks like the Vöktun Vatnajökuls graph for Grimsvötn has become stuck, the date is changing but the line hasn’t moved one way or the other for more than a week.

    • http://www.bbc.co.uk/news/world-europe-39293086

      Mount Etna: BBC crew caught up in volcano blast

      A BBC team and a number of tourists have suffered minor injuries after being caught up in an incident on the erupting volcano Mount Etna in Sicily.
      “Many injured – some head injuries, burns, cuts and bruises,” tweeted BBC science reporter Rebecca Morelle.
      Lava flow mixed with steam had caused a huge explosion, which pelted the group with boiling rocks and steam, she said.
      She said about eight people had been injured, with some evacuated from the mountain by rescue teams.

      “Bbc team all ok – some cuts/ bruises and burns. Very shaken though – it was extremely scary,” she tweeted.
      The BBC reporter said a volcanologist at the scene said it was the most dangerous incident he had experienced in his 30-year-career.
      She said a 78-year-old woman had been very close to the blast, but had got away safely.
      The volcano spewed lava up into the sky in the early hours of Thursday morning, for the third time in three weeks.
      It’s the first eruption for more than a year.

        • The media don’t seem to understand Etna at all. They said similar during that major paroxysm in Dec 2015. They clearly don’t grasp the concept of paroxysm vs. continual minor activity.

          As for the incident earlier today, why on earth were they so damn close? Surely getting near the summit region during an eruption is stupid! Especially when they had a warning just before the main explosion. Shouldn’t really have been that much of a “surprise”.

          • From what I heard they weren’t actually all that near the summit, they were near a lava flow some distance away in an area that would normally be much safer than the summit, and the lava exploded when it rolled over some snow.

  17. Radio Studio 7 webcams has great views. Refreshes about every minute.

    Our spam filter seems a bit overactive at the moment and likes to put things in quarantine. I blame Brexit. You may need to be patient if your comment seems to have evaporated: it will be waiting for an admin to wake up

    • From the article, the Judge wasn’t too pleased and considered it as a crafted incident. Given the sliminess of South Florida Lawyers, I’d say the Judge knows them well.

    • Thanks! It is well worth reading the original sources. I have some doubt about the ‘shutting down’ hypothesis, purely on grounds of probability: the chances that the only earthquake we have experienced happens to be the last ever are quite slim. But one should look at the data. Hough’s paper claims that the on-going quakes are not aftershocks. She may be right, but it is also possible that her model failed to fit because the original earthquakes were weaker than thought (she actually uses the difference between the first four earthquakes but that may also open to question. I would agree with Stein that a repeat of New Madrid is unlikely this century. But an event on another part of the fault cannot be excluded.

      • the sand blow region is pretty big…there are some as far south as Northeast Louisiana. Also there are a fewanomalous uplifts in the region —one is roughly around Reelfoot Lake and another one is in NE Louisiana (Monroe Uplift) and one is in Mississippi (Wiggins Uplift).

        There is a lot going on geologically in this area. I find it so fascinating. I also don’t think Dr. Stein is right in that the system is shutting down but I think the idea of migrating episodic quakes that he’s come up with might be a model for the central US and other continental interiors. The Wabash in Indiana was active thousands of years ago but isn’t very active at the moment, for example.

  18. Another star for Bard

    Thursday
    16.03.2017 10:10:32 64.617 -17.483 7.1 km 3.9 99.0 3.3 km SE of Bárðarbunga

    from IMO.

    Looks like another nice stack for Herðubreið too on 3Dbulge.

    Can some one captured the 3Dbulge graph & put it on here?

  19. I should also say that after Alberts next epic venture I will rant about volcanoes in Guatemala while Albert is doing what Albert normaly is doing when he is not writing wonderful things for us all to read 🙂

  20. In the southeastern part of the Netherlands there are rifts which are part of the Lower Rhine Graben. In 1992 a strong earthquake took place with its epicentre in Roermond, magnitude was 5.8 on the Richter Scale.

    But are severe earthquakes with a magnitude of 7 on the Richter Scale also possible in the Lower Rhine Graben?

    • No. It peaks at a bit over M6. I remember the Roermond earthquake. It woke me up.

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