Quakes in Midwest largely unstudied

There is the potential for a devastating earthquake in the region, scientists say.

CHAMPAIGN, Ill. (AP) — Scientists say they know far too little about Midwestern seismic zones such as the one that rumbled to life under southern Illinois on Friday morning, but some of what they do know is unnerving.

The fault zones beneath the Mississippi River Valley have produced some of the largest modern U.S. quakes east of the Rockies, a region covered with old buildings not built to withstand seismic activity.

And, when quakes happen, they’re felt far and wide, their vibrations propagated over hundreds of miles of bedrock.

Friday’s quake shook things up from Nebraska to Atlanta, rattling nerves but doing little damage and seriously hurting no one. It was a magnitude-5.2 temblor centered just outside West Salem in southeastern Illinois, a largely rural region of small towns that sit over the Wabash fault zone. The area has produced moderately strong quakes as recently as 2002.

But it hasn’t been studied to nearly the degree of quake-prone areas west of the Rockies, particularly along the heavily scrutinized Pacific coast.

“We don’t have as many opportunities as in California,” said Genda Chen, associate professor of engineering at the University of Missouri-Rolla, which sits near the well-known and very active New Madrid fault zone.

“We cannot even borrow on the knowledge they learn on the West Coast” because quakes that happen in California — where tectonic plates beneath the Earth’s surface collide — are so different from Midwestern quakes that happen far away from the edges of the nearest plates.

It isn’t entirely clear, for instance, whether the Wabash faults are related to the New Madrid faults.

Some scientists say they are related, noting that the Wabash faults, which roughly parallel the river of the same name in southern Illinois and Indiana, are a northern extension of the New Madrid zone. Others say they’re not.

The question of whether Friday’s quake was centered along a branch of the New Madrid zone or not is of more than academic interest. The area even now produces smaller, very regular quakes, and experts say it has the potential to produce a quake that could devastate the region.

The Wabash faults have the potential to do the same, said Columbia University seismologist Won-Young Kim.