Seated man in a hard hat assesses sediment patterns in a dug trench
Trenching across linear ridgetop spreading features, like scarps called sackungen, revealed colluvial sediment that indicates past earthquakes and postdates the deposition of the Peoria loess (the light tan sediment) about 11,000 years ago. Richard Briggs of the U.S. Geological Survey examines the wall of the sackungen in the trench. Credit: Ryan Gold

Human-swallowing fissures, a backward flowing Mississippi River, and so-called earthquake lights were just a few of the strange phenomena reported during the series of powerful intraplate earthquakes that occurred in the New Madrid Seismic Zone between December 1811 and February 1812.

Those earthquakes, which took place in Arkansas and along the Reelfoot reverse fault in Missouri and Tennessee, made history as some of the strongest to occur east of the Rocky Mountains, but many secrets remain about prior seismic activity in the New Madrid region.

“The earthquake record is just really sparse” in this area, says Jaime Delano, a geologist with the U.S. Geological Survey (USGS) Geologic Hazards Science Center in Golden, Colo. However, high-resolution airborne lidar data from this region have given Delano and her collaborators new insights into past shaking events in the New Madrid Seismic Zone, which they reported in a study in Geophysical Research Letters (GRL).

The lidar data revealed linear ridgetop spreading features like scarps, called sackungen, that hadn’t been previously described, says Ryan Gold, also a geologist with USGS in Golden and a coauthor of the study. The researchers mapped the sackungen on bluffs in the Mississippi River valley in northwestern Tennessee. Those features “likely form or are reactivated during large earthquakes,” the researchers wrote.

The sackungen were concentrated on the hanging wall of the Reelfoot fault, and their preferential orientation indicated ground motion perpendicular to the fault strike. These observations are consistent with the notion that at least one earthquake occurred on the southern portion of this fault since a layer of windblown sediment called the Peoria loess was deposited in this region approximately 11,000–30,000 years ago.

“It would be really cool to trench more of these” sackungen.

Additional work by Delano, Gold, and their colleagues not reported in the GRL study agrees with this assessment. At the Geological Society of America’s (GSA) 2018 annual meeting in Indianapolis, Ind., Gold reported that paleoseismic trenching across sackungen revealed four packages of colluvial sediment that indicate past episodes of ground shaking and postdate the deposition of the Peoria loess. (Publication of these findings is forthcoming.)

The trenching site is located approximately 8 kilometers from Samburg, Tenn., a small town on the southeastern shore of Reelfoot Lake (which was formed as a result of the 1812 New Madrid earthquake along the Reelfoot fault, Gold notes).

The researchers performed radiocarbon and luminescence dating on samples collected from the four colluvial packages. They also measured the concentrations of lead and cesium isotopes in the samples.

On the basis of this dating, Gold reported in his GSA presentation a history of four earthquakes (or earthquake sequences) that occurred before 1860, one of which occurred thousands of years ago in the early to middle Holocene and the rest of which occurred after 340 CE.

“It would be really cool to trench more of these” sackungen to determine whether the properties of the sediments underneath them echo those of the collected samples, Delano says. Together, these studies set a precedent, she says.

The orientation of sackungen “could be used to infer the source fault for past earthquakes here and elsewhere,” the researchers wrote in GRL.

“This is another way of looking at the problem that may not have been considered yet,” Delano adds.

“Innovative and Comprehensive” Work

The team’s work “is innovative and comprehensive, demonstrating yet another exciting application of high-resolution lidar topography for studying faults and ancient earthquakes,” says Samuel Johnson, a geoscientist at the USGS Pacific Coastal and Marine Science Center in Santa Cruz, Calif., who was not involved with the study.

“Sackungen have been almost exclusively described in mountainous terrain, so their recognition and documentation in the far more subtle, low-relief, midcontinent Mississippi River valley region is especially interesting,” Johnson says.

Besides bolstering the region’s known seismic record, the team’s analysis underscores the difficulty of predicting future seismic activity for this region, given the variable frequency of past earthquakes. The “nonperiodic earthquake recurrence has important implications for seismic-hazard and geodynamic modeling in the New Madrid Seismic Zone,” the researchers wrote in the abstract for Gold’s GSA presentation.

—Rachel Crowell (; @writesRCrowell), Science Writer

This article is part of a series made possible through the generous collaboration of the writers and editors of  Earth magazine, formerly published by the American Geosciences Institute.


Crowell, R. (2019), Secrets from the New Madrid Seismic Zone’s quaking past, Eos, 100, Published on 09 April 2019.

Text © 2019. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

4 replies on “Secrets from the New Madrid Seismic Zone’s Quaking Past”

  1. This post has to do with the possibility of the next large quake on the New Madrid Fault hitting the Midwest towards the end of this year. I have outlined the main reasons why I have come to this conclusion below. I have spent the last 11 years studying climate related material. I became interested in quakes after the Great Tohoku Quake in March 2011. This is how and why I eventually came to read about quakes on the NMSZ. From there I could not help but notice that all of the large quakes on the NMSZ had a connection. That was that the main correlation is always related to the longer term solar cyclical events known as a Gleissberg cycle, solar grand minima, and the 11 year solar cycle. The first major quake recorded on the New Madrid was at 1pm on December 25th of 1699, as noted by a French missionary in a group of explorers. This happened during the Maunder Minimum, and also during the latter stage of a solar minimum. Dec 11th of 1811 was the next of a series of 3 large quakes on the New Madrid. The second quake was on January 23rd 1812, and the 3rd and largest struck on February 7th 1812. This takes place during the Dalton Minimum, and right at the low point of SC 5.

    Other approximate years with large quakes on the NMSZ were in AD300, AD900 and AD1450. Now take a look at the JG/U 2K temp graph and see what it shows is happening to global temps for each of those 3 quakes. All three occurred during an obvious down turn in global temps. The year 1450 is a recognized grand minimum. The other two are at the very least a Gleissberg cycle. The one around 300 AD is certainly a GM which looks like it would have rivaled the Maunder GM. It affects temps for around 60 years. The sharp drop around 900 AD is what I would call a quarter note of around 15 years in length, and so likely a Gleissberg cycle. It would be interesting if it the state of the solar cycle could be determined to see if those 3 large quakes happened in the midst of the solar minimum. Other moderately strong quakes were on January 4th in 1843, at the solar minimum, and on October 31st 1895. This last one occurs after the maximum of SC 13 and 8 years prior to the solar minimum. Most recent was on November 9th 1968 two plus years after the
    solar minimum. An interesting footnote is that this occurs around 3 or 4 months after the peak of SC 20 when sunspots rapidly drop 60% from that peak as seen on Dr Svalgard’s high res ssn graph.

    So commonality with all of the major quakes on the NMSZ is they all
    strike mainly in the winter, close to or during the solar minimum, and
    either during a solar grand minimum, during a Gleissberg cycle, or in
    the last case after a rapid plunge in sunspots. Which raises the
    question in my mind is the next New Madrid quake now close at hand and
    ready to strike in this upcoming winter? If not this winter, then
    potentially next winter which would place it slightly after the end of
    this current minimum. It is clear to see that this year 2019 will be the
    heart of the solar minimum. The solar minimum is certainly low and
    prolonged as the last one was in 2008/09. In 2008 a moderately strong
    quake hit on the Wabash Fault Zone, close to the New Madrid Zone.
    Alternatively the solar minimum at the end of SC 25 will be the next
    likely timing for a large quake on the NMSZ, if SC 25 remains as low or
    lower than SC 24. Does this warrant issuing a warning to the proper
    emergency agencies to be on stand by alert, and/or to issue a general
    alert to the population at risk?

  2. Tennessee had a 3.6 this morning. Watch out for this coming winter.
    This could be the real deal, although there is no way to know the
    intensity of a potential quake. The danger is that all of the known
    large quakes occur under current low solar conditions. An interesting
    offshoot idea from what I see in this is that the JG/U 2K temp graph
    could potentially be used as a method for finding previous unknown large
    quakes on the NMSZ.

    The older large quakes for which evidence has been found occurred in
    300 AD, 900 AD, and 1450 AD. But why not around 540 AD where a steep
    temp drop which equals 1450 AD can be seen? Or around 420 AD? Or around
    800 AD? Or around 1125 AD? Or around 1230 AD? Or around 1340 AD? Those
    are all sharp temp drops and most likely Gleissberg/GSM cycles. More
    than that, note how those years would fill in the blanks which would
    then show a large quake around every 100+ years, ie known 300, then 420,
    540, 680, 800, known 900, 1125, 1230, 1340, known 1450. The rest is
    known 1699, 1811/12, 1895. An intriguing idea, no?

  3. I also have thoughts as to when other large quakes may have occurred on the NMSZ, and the most likely time frame for such events to have taken place. If you are interested.

  4. Thanks to Eos and Rachel Crowell for the nice write-up.

    The paleoseismic trenching study at the Paw Paw site mentioned in the article, “Four major Holocene earthquakes on the Reelfoot fault recorded by sackungen in the New Madrid Seismic Zone” is published in JGR Solid Earth (

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