Transcript for Hidden Fury, segment 06 of 11
Susan, can you come and look at this, please?
When will the next large earthquake strike? What will it do to the central United States? For decades scientists have been searching for the answers, but the earthquake zone does not reveal its secrets easily. The Mississippi River, running chocolate brown with silt, buried the zone under three thousand feet of mud. Advanced earthquake studies developed in California do not work well here.
We have to sample everything from the surface because the seismicity is between five and fifteen kilometers deep. You can't dig a hole that deep and look for something. We don't quite have that technology. In a San-Andreas-like situation, you can see the fault. You can walk out, and you can find the trace of it. You can see it in the dramatic topography that creates the San Andreas Lake, but in New Madrid, it's not right there for us to see. It's not right there for us to map.
Borrowing methods used for oil exploration, scientists look through the surface layer of mud and probe the rocks below. In the early nineteen seventies they discovered a buried swath of fractured, twisted rocks about two hundred miles long and forty miles wide. The structure was named the Real Foot Rift. The late Doctor Otto Nutley, a geophysicist at Saint Louis University, used newspaper reports to locate earthquakes in the rift. His results have stood the test of time, despite the reliability of old news stories. Modern instruments corrected the reliability problem.
Up until nineteen seventy-four, we just knew that earthquakes were occurring down in the boot heel of Missouri. Nineteen seventy-four, Saint Louis University was able to establish a modern, dense, regional seismographic network. As soon as that was installed and earthquakes were recorded, very strong patterns emerged, showing where the earthquakes occurred in the region.
We, with our seismic networks, can record and locate an earthquake about every two days, and there would be an earthquake about magnitude two to two-and-a-half, and certainly that level of activity and the number of magnitude five earthquakes that we have seen in the last thirty years is much larger than anywhere else in the eastern United States so relative to, you know, other areas of the eastern United States, New Madrid is a hot spot.