Peculiar Earthquake Touches Southern Illinois
By: Andy Waterman
Posted: Tuesday, June 7th
JACKSON COUNTY-- Experts are studying an early morning earthquake that rattled some people awake in eastern Missouri and southern Illinois. Some of you may have felt the tremor just after three o'clock Tuesday morning, it was a magnitude 4.2 earthquake
The U.S. Geological Survey says the quake was centered near Sullivan, Missouri, about fifty miles southwest of St. Louis. People felt the rumbling as far west as Columbia, Missouri, and as far east as Carbondale.
When SIU geology professor James Conder checked overnight readings from the university's seismograph Tuesday morning, he was a little shocked.
"I thought well, that's rather interesting," he said.
The equipment in Carbondale registered activity from the 4 earthquake near Sullivan. What surprises him is that it happened nowhere near the New Madrid Fault line, the area's most active fault.
"This one is pretty well outside the New Madrid region," he explained. "So this is probably the biggest earthquake in Missouri this far outside the New Madrid system as far as we've been reading earthquakes."
Federal geology officials say the quake was more than three miles deep. The problem is, there's no telling what fault may have caused it.
"There are faults all over the midwest," Conder said. "Very deep ones that haven't been mapped very well, so I'm sure there is some sort of fault that it occurred on but it probably has not been mapped very well."
Conder says Sullivan sits on the northern edge of the Ozark Plateau, and that may be the key to this quake.
"Those plateaus, they erode, they lose mass, and so they tend to pop up," he said. "Or if you have rivers carrying sediment to somewhere else it weighs down that region so it'll cause stresses that way. So it probably has something to do with these vertical stresses with erosion of the plateau."
What's also odd, is that there were no aftershocks.
"I looked through the records to see if there was any smaller earthquakes that came with it, and could not find any, so it seems to be just a single little event," Conder explained.
We've heard from some viewers who thought they felt the quake this morning, and even more who did not. Conder says the tremor only lasted about five seconds here in southern Illinois.
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