KIMMSWICK, Mo– A magnitude 2.5 earthquake rattled southern St. Louis Couty and Jefferson County on the night of December 6.
“A big shake and a slight thud,” that’s what Carrie Palombo’s Mom told her after an earthquake shook the ground near Kimmswick, MO in Jefferson County just after 8:30 PM on Tuesday.
Her parents, in Imperial, MO, immediately went outside to see what had happened and found several neighbors outside doing the same thing. Neighbors conversed about the noise and movement, with most assuming an earthquake.
The United States Geological Survey (USGS) confirmed a magnitude 2.5 earthquake occurred at 8:32 PM 2 miles east of Kimmswick, across the Mississippi River in Monroe County, Illinois with a depth of 5.1 KM. Weak to light shaking was reported from Festus to St. Louis City.
Residents in southern St. Louis County and Jefferson County reported “shaking” and “rattling.” Even mentioning their dogs suddenly barking or jumping up unexpectedly. No reports of any damage.
Minor earthquakes occur in the St. Louis region, although not that often. However, another quake occurred as recently as April 29 of this year. A magnitude 2.8 earthquake had an epicenter just south of Valley Park, Missouri.
These quakes are part of the Illinois Basin-Ozark Dome extending to the more active New Madrid Seismic Zone.
Washington University in St Louis geophysics professor Michael Wysession explained that earthquakes that occur in the middle of the continent, like this one and the quake from April, happen because of the drifting of tectonic plates.
The North American plate drifts west at a rate of an inch to an inch and a half per year. As the plate encounters a “lumpy” mantle, it flexes and bends a bit.
Using an analogy of an old wooden ship moving along the waves. “As it goes, you hear the creaking and the groaning of the boards and the mast and that’s exactly what North America does.”
Adding that quakes like these could also be attributed to a weak spot on the North American plate, a common occurrence as the plates continuously drift apart and together.
