In 1811 and 1812, Missouri’s New Madrid Seismic Zone produced some of the largest earthquakes ever in the continental U.S. If a future quake is centered near the southeast Missouri fault, Jeff Briggs with the State Emergency Management Agency says the shaking will be felt for hundreds of miles in every direction.
New Madrid Seismic Zone – Quaternary Fault Localities. Earthquakes with magnitudes equal to or larger than 2.5 are shown by the yellow dots. Photo courtesy of USGS.
“That’s because of the way the geology is here in the Midwest,” says Briggs. “Out west, it’s very mountainous. The rocks are broken up. So the shaking doesn’t travel as far. The energy gets dissipated. Here in this part of the country though, there’s a lot of loose, sandy soil, wet soil, riverbeds.”
More than 500,000 Missourians will participate Thursday morning in the annual “ShakeOut” earthquake drill by dropping to their hands and knees, taking shelter under a table or desk, covering their heads and holding on. In all, nearly 2.5 million people are registered in the 14 central U.S. states that could be impacted by a New Madrid Fault earthquake.
The “ShakeOut” earthquake drill kicked off in the central U.S. about 200 years after the deadly quakes of 1811 and 1812. Geologists say there’s a 7-10% chance of another major earthquake occurring in a 50 year period.
Unlike tornadoes and floods, there’s no way to predict when an earthquake will hit.
“Scientists have never figured out a way to predict when it’s going to happen, what time of year it’s going to happen or anything. It’s one of the real challenges of earthquake safety,” says Briggs.
He says a 3.6 magnitude earthquake that was widely felt in southeast Missouri on Sunday is a reminder why the drill is important.
“It was based just about 25-30 miles south of Kennett, right down there in the bootheel just barely into that northeastern tip of Arkansas. That was an example of the kind of earthquakes we get down there from time to time,” says Briggs.
The New Madrid Seismic Zone is not the only fault in Missouri. The Humboldt Fault Zone is in the northwest part of the state. It extends from northeastern Kansas to central Oklahoma and is along a buried geologic feature called the Nemaha Ridge. Sometime it is referred to as the Nemaha Fault Zone due to its proximity.
Those who want to participate in tomorrow’s drill can sign up by going to www.shakeout.org/centralus
