Another relatively weak earthquake rattled Illinois last night adding to other recent seismic events in the area. According to USGS, the magnitude 2.0 event struck near the Illinois/Missouri border near Monroe City which is south of St. Louis, Missouri. The earthquake, with a depth of 11.2 km, struck at 8:23 pm local time yesterday. People that reported they felt and/or heard the quake were in both states.
There have been steady earthquakes about 100 miles south, but that area is closer to the heart of the New Madrid Seismic Zone, or NMSZ for short, where seismic activity has been elevated in recent months.
Earthquakes with a magnitude of 2.0 or less are rarely felt or heard by people, according to USGS, but once they exceed 2.0 more and more people can feel them. While damage is possible with magnitude 3.0 events or greater, significant damage and casualties usually don’t occur until the magnitude of a seismic event rises to a 5.5 or greater rated event.
Illinois is at risk from two major seismic zones, the Wabash Valley Seismic Zone and the New Madrid Seismic Zone. The Wabash Valley Zone is located between southeastern Illinois and southwestern Indiana. According to USGS, the largest earthquake in recent years occurred on the Wabash Valley Seismic Zone. This earthquake registered a magnitude of 5.4 and occurred in Mt. Carmel, Illinois on April 18th, 2008…