This part of the Midwest isn't exactly San Francisco, or even Oklahoma City, where an outbreak of earth tremors is thought to be linked to deep-well injection by the oil industry. But there are fault lines beneath our feet, a University of Illinois geologist said Monday, and seismographic studies are in progress to help keep track of what they're doing.

Stephen Marshak (photo), director of the UI School of Earth, Society & Environment, spoke to an overflow crowd in the Extension Auditorium in Champaign, in a lecture sponsored by Extension and East Central Illinois Master Naturalists. An estimated 70 people attended.

Earthquakes along the New Madrid fault in southeastern Missouri in 1811-12 were so strong that for a time the flow of the Mississippi River was reversed, Marshak said. Currently seismologists are studying a broad band stretching across Southern Illinois from the Missouri Ozarks into Indiana and Kentucky. He said the research is intended to enable geologists to keep a close watch on fault-line activities.

In a talk geared to a broad audience, Marshak presented a quick grounding in plate tectonics, different kinds of faults, and the different shaking motions that can occur. An accompanying slide show illustrated the locations of major faults around the world, and the devastation of large earthquakes in recent years.

The lecture counted as Continuing Education credit for Master Naturalists.

Story by Teresa DeWitt (2013)