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ST. LOUIS – Wednesday evening’s earthquake in southeast Missouri was the largest quake within 70 miles in the last three decades.

The 4.0 magnitude earthquake happened at 8:53 p.m. in Williamsville, with shaking was reported about as far north as Interstate 70 in both Missouri and Illinois.

“A magnitude 4 will be felt over a very wide area. There were reports that this was felt in Kansas City and St. Louis. But feeling an earthquake is very different than the earthquake causing damage,” said Dr. Robert Herrmann, emeritus professor of geophysics at Saint Louis University.

Close to the epicenter, the earthquake would have been strongly felt. The Missouri State Emergency Management Agency reported that in addition to car alarms sounding there were scattered reports of bottles falling off of shelves, pictures and clocks coming off of walls, and at least one report of drywall cracking.

“It would just be in the threshold of doing minor damage. If we had a larger earthquake, like a magnitude 5, then there could be minor building damage,” he said.

Dr. Herrmann says that we’re in a place where earthquakes occur with some frequency. They’re all related to the forces within the earth and places where there’s a weakness and movement. This quake occurred on the periphery of the New Madrid fault line.

“What’s different about New Madrid is that if you put all the little earthquakes together they line up in a nice long linear trend and it might be more 30, 40, 50 miles long and that represents a major fault. Other places, if there’s just a zone of weakness it breaks,” Dr. Herrmann said. “So this is not part of the New Madrid fault but it’s part of the process that gives rise to the earthquakes at New Madrid.”

And in the case of a big event, it’s important to respond properly.

“I would not lose sleep on it but people should know how to react. Just like they should know how to react to any natural disaster,” he said.

If there were major shaking, get out of the building so it doesn’t collapse on you. But when you go outside be aware of electrical wires that may have fallen and gas leaks.

“Some of the things you would worry about would be the same things you would worry about in severe weather,” Dr. Herrmann said.

Our part of the country is well monitored by instrumentation.

“Everything goes to a computer in real-time. And so within a minute of the earthquake, a computer will spit out a location and size and within ten minutes a human being will look at what the computer did and if it’s significant the human being will then notify different agencies,” Dr. Hermann said.

SEMA has trained every year for natural disasters. They go from the state to local levels and get everybody organized and make sure everyone communicates. Dr. Herrmann said our earthquake preparedness is much better than it was years ago.