The New Madrid earthquakes broke up rock like this section of rock face, which was later filled with sand. This photo, from Mississippi County, Mo., was taken in 1904.
Credit M.L. Fuller (Image 336) / USGS
The earthquakes caused the Mississippi River to overflow its banks. The high water brought sand, which covered up several feet at the base of trees. The trees survived and grew roots into the new sand, which had been washed away by the time this picture was taken in 1904.
The magnitude-5.8 earthquake that rattled the eastern U.S. on Tuesday took everyone — even geologists — by surprise. But even when there are reasons to think an earthquake could be around the corner, scientists still can't make good predictions.
Education secretary Arne Duncan, Gov. Jay Nixon, Homeland Security secretary Janet Napolitano and Congressman Russ Carnahan watch students at Carnahan High School participate in the "Great ShakeOut" earthquake drill.
Governor Jay Nixon, Congressman Russ Carnahan, and two members of President Obama's cabinet - education secretary Arne Duncan and Homeland Security chief Janet Napolitano - watched as the 19 students in Lucy Duffey's class dropped to the ground, covered their heads, and held onto tables in the library.
A woodcut depicting damage from the New Madrid series of earthquakes in 1811 and 1812. FEMA Administrator Craig Fugate says the threat of earthquakes on the New Madrid fault remain. (Via Wikimedia Commons)
Tomorrow marks the St. Louis kickoff of the bicentennial events commemorating the earthquakes that struck the New Madrid Seismic Zone in 1811-12. You’ve probably heard stories about those quakes: that church bells rang in Boston, that the Mississippi River ran backwards. Much of that, it turns out, is legend. So what do we know about the New Madrid fault and the risk it poses to the modern Midwest?