14 News, The Tri-State's News and Weather Leader-Earthquake Rattles the Heartland
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Earthquake Rattles the Heartland
By: Heartland News
CAPE GIRARDEAU, Mo. -- Friday morning, at approximiately 4:37am Friday morning, the ground also shook across the Heartland.
The United States Geological Survery (USGS) measures the earthquake as a magnitude 5.2 earthquake. It was centered 8 miles northwest of Mt. Carmel, Illinois.
According to the USGS, earthquakes east of the Mississippi River are felt more widely than those in the west. The early morning quake was the strongest earthquake in southern Illinois since November 1968, when a 5.4 earthquake occurred.
The 5.4 quake is classified as moderate. It was followed by a 4.6 aftershock about 10:15 a.m. Friday. The earthquake was felt all across the Midwest as far west as Kansas, as far north as Upper Michigan, and as far south as Georgia. A couple of our Raycom Media sister stations were on the air live while the earthquake occured. You can watch the video from their newscasts. There are links on the right side of the page.Earthquake Location:
Another concern is the potential for the adjacent New Madrid seismic zone to generate severe earthquakes. Three very large earthquakes devastated the area the winter of 1811-1812. The three major quakes occured only a few weeks apart on Dec. 16, Jan. 13, and Feb. 7. They generated hundreds of aftershocks which continued for years.
Here is an image of the seismograph from Portageville, Missouri.
EARTHQUAKES IN THE ILLINOIS BASIN - OZARK DOME REGION 
This large region borders the much more seismically active New Madrid seismic zone on the seismic zone's north and west. The Illinois basin - Ozark dome region covers parts of Indiana, Kentucky, Illinois, Missouri, and Arkansas and stretches from Indianapolis and St. Louis to Memphis. Moderately frequent earthquakes occur at irregular intervals throughout the region. The largest historical earthquake in the region (magnitude 5.4) damaged southern Illinois in 1968. Moderately damaging earthquakes strike somewhere in the region each decade or two, and smaller earthquakes are felt about once or twice a year. In addition, geologists have found evidence of eight or more prehistoric earthquakes over the last 25,000 years that were much larger than any observed historically in the region.
Earthquakes in the central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much broader region. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi). *Source: USGS
