“I may not be here when it happens,” said Lueker. “Or it may happen while we’re talking. You don’t know.”
When it does happen, Lueker said Mount Vernon, the Jefferson County seat, likely will be a staging area for support flowing into Tennessee and Missouri – unless the Mount Vernon airport itself is too damaged. He doesn’t – can’t – know.
Uncertainty is the maddening aspect of earthquakes. They can’t be predicted, even very big ones. We know they happen frequently along the earth’s tectonic plates. We also know there are no such plates in the central United States, yet that part of the country has had major earthquakes in three zones: the New Madrid fault, which on computer models looks like Harry Potter’s scar slashing across Arkansas, Missouri and Tennessee; the Wabash Valley fault in Illinois and Indiana; and the East Tennessee Seismic Zone that runs into Alabama.
These are not like the faults in California, which last had a major earthquake in 1994, when the magnitude 6.7 Northridge temblor killed 57 people and caused $20 billion in damages. The mid-continent faults rupture less often; New Madrid gets the shakes maybe 200 times a year, about a tenth the number in California. And earthquakes in the central United States tend to be smaller. The New Madrid fault appears to have a big rupture every 300 years or so; the Wabash Valley has one perhaps every 500 years.
But when quakes do hit the central United States, geology means they are felt much farther away, because the Earth’s crust in the region does not absorb the shock waves in the way it does in the Western United States. “The Northridge earthquake was barely felt in Las Vegas, 250 miles away,” said Gary Patterson, director of education and outreach at the Center for Earthquake Research and Information at the University of Memphis. “Here, a large quake would be felt 1,200 miles away in Canada.”