New Madrid Earthquake Guide for the Central Mississippi Valley

There were no seismographs in North America at the time, so everything we know comes from written accounts and from geology. The USGS currently gives these preferred magnitudes, taken from its 2014 National Seismic Hazard Map. Older USGS figures were higher, and other agencies give a range of 7.0 to 8.0, so treat the numbers as estimates.

The geologic record shows 1811-1812 was not a one-off. A 2009 USGS fact sheet describes earlier sequences of large quakes around A.D. 1450, A.D. 900 and 2350 B.C., traced from ancient sand blows (places where sand and water erupted from the ground). A 2002 USGS study by Tuttle and colleagues found that the gap between the last three sequences could be as short as about 200 years or as long as about 800, and averaged about 500.

This is the most important difference from California. The USGS says the rocks in the eastern half of North America are older, and their faults have had longer to heal. Seismic waves cross them with less energy lost, so they travel much farther. Western rock is younger and more broken, and it soaks up more of that energy.

In practice, you do not need to live next to the fault to feel strong shaking. The USGS expects Memphis to take the worst damage, but it also expects damage in St. Louis, Little Rock and many small and mid-sized towns.

Missouri SEMA adds that a magnitude 6.0 or larger quake has happened about once every 80 years. The last was a magnitude 6.6 near Charleston, Missouri in 1895. SEMA also says the USGS considers about magnitude 7.6 the strongest likely in the zone. Nobody can predict the day, and the Missouri Geological Survey says plainly that it is impossible to predict when or where an earthquake will happen.

Is the zone shutting down? Some researchers have argued that it might, because GPS instruments show little movement at the surface. The USGS reviewed that argument with outside experts in 2006 and found it was not a convincing reason to lower the hazard. Its reasoning was the long geologic record and the steady stream of small quakes. Missouri SEMA says the zone averages about 200 measured quakes a year.

For a sense of the worst case, a 2009 study for FEMA by the Mid-America Earthquake Center at the University of Illinois modeled all three fault segments breaking together, each at magnitude 7.7. The authors designed this to stand in for the segments breaking one after another over time. It is a planning scenario, not a forecast. Across eight states it estimated:

The same study found Tennessee, Arkansas and Missouri hit hardest, with Illinois and Kentucky also hit. It estimated that about 42,000 search and rescue workers in 1,500 teams would be needed. Help would be stretched thin over a very large area. That is the strongest local argument for being able to look after your own household for days.

Liquefaction happens when shaking makes wet, sandy soil lose its strength and behave like quicksand. Buildings can sink or tilt, and sand and water can boil up to the surface. The Missouri Geological Survey says the sandy soils of southeast Missouri are very susceptible to it. The USGS says that in a repeat of 1811-1812 it would expect this ground failure across northeast Arkansas, southeast Missouri, western Tennessee and Kentucky, and southern Illinois.

CUSEC says most structures in the region were not built to withstand strong shaking, unlike buildings in places like California. Missouri SEMA warns that unreinforced masonry buildings (brick or block walls with no steel inside) from Memphis to St. Louis could be seriously damaged. The USGS notes that in Memphis few buildings went up under seismic building codes, and that many large ones would be especially vulnerable, including unreinforced schools and fire and police stations.

Earthquake insurance: standard homeowners policies do not cover earthquake damage (Ready.gov, CentralUSQuake.org). Coverage is a separate endorsement or policy. It usually carries a deductible of 10 to 20 percent of the rebuilding cost, with a separate deductible for contents. CentralUSQuake.org gives an example: with a 20 percent deductible, a 200,000 dollar home could leave you paying up to 40,000 dollars before the policy pays anything. In 2019 the Missouri Department of Commerce and Insurance reported that coverage in the New Madrid area fell from over 60 percent of homes in 2000 to just under 14 percent in 2018, while average premiums in the six New Madrid counties rose nearly 700 percent. Ask your agent what your own policy covers.

⚠ There is no earthquake early warning here. The USGS ShakeAlert system covers only California, Oregon and Washington. In the central US you will get no seconds of notice. The first shaking you feel is your signal to act.

The Great Central US ShakeOut is a regional earthquake drill held every year on the third Thursday of October at 10:15 a.m. local time (Missouri Geological Survey). The 2026 drill was October 15. Households, schools and businesses can register, and the Missouri Geological Survey says you can also run your own drill on any date. February is Earthquake Awareness Month in Arkansas, and Earthquake Preparedness Month in Illinois.

Alerts: because quakes give no warning, the purpose of alert sign-ups is news after the event: road and bridge closures, boil-water notices, shelters. Arkansas lists its ReadyAR Emergency Alerts on the state Citizen Alerts page. In other states, check your state emergency agency and your county emergency management office for their alert service.