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The 2008 Illinois earthquake was one of the largest
earthquakes An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
ever recorded in the Midwest state of Illinois. This moderate strike-slip shock measured 5.2 on the moment magnitude scale and had a maximum Mercalli intensity of VII ''(Very strong)''. It occurred at on April 18 near Bellmont and Mount Carmel, Illinois, within the Wabash Valley Seismic Zone. Earthquakes in this part of the country are often felt at great distances.


Tectonic setting

Situated in a stable continental region of the Midwestern United States, the Wabash Valley Seismic Zone (WVSZ) is an area of dispersed seismic activity that encompasses the border areas of Illinois, Indiana, and Kentucky. This broad, multistate zone of intraplate seismicity lay just to the north of the New Madrid Seismic Zone and comprises both strike-slip and dip-slip earthquake mechanisms across numerous named faults,
graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...
s, and anticlines.


Earthquake

Rapid development and expansion of services from the United States Geological Survey was taking place in the 2000s in terms of earthquake monitoring and information dissemination services. A number of products from it and its subdivisions that relay information to the public over the Internet were displayed during the event. An automated system from the National Earthquake Information Center, for example, sent an initial notification containing magnitude, depth, and location within two and a half minutes of the mainshock.


Felt area

The shock was felt as far west as Omaha, Nebraska, as far south as Atlanta, Georgia, as far east as Kitchener, Ontario, and West Virginia, and as far north as the Upper Peninsula of Michigan. The earthquake was felt so far away, compared to earthquakes in other regions, because the old, rigid bedrock beneath much of the Midwest allows the seismic waves to propagate further.


Damage

Close to the epicenter in Mount Carmel, Illinois, a woman was briefly unable to exit her home due to a collapsed porch, and a two-story apartment building was evacuated because of loose and falling bricks. The Edwards County sheriff's department took reports of minor damage in West Salem, Illinois. Just across the Wabash River in Indiana, Unit 4 at the Gibson Generating Station automatically shut down due to its vibration sensors, and in Princeton, a woman was cut when a crystal figurine was knocked from a shelf in her home. A man had an eye injury at an unknown location, but medical attention was not sought. In Louisville, Kentucky, some bricks broke off from an older building near downtown. Slightly further away in St. Louis, Missouri, a portion of the South Kingshighway Boulevard
viaduct A viaduct is a specific type of bridge that consists of a series of arches, piers or columns supporting a long elevated railway or road. Typically a viaduct connects two points of roughly equal elevation, allowing direct overpass across a wide v ...
were closed because of loose pieces of concrete, but whether this was debris-related is unknown, and traffic resumed half an hour later. Several chimneys also collapsed in south St. Louis, the St. Francis de Sales Oratory reported damage to its steeple, and the Basilica of St. Louis King of France reported small fragments from the mosaic ceiling. About 35,000 people in St. Louis County were without power because the Labadie Power Station went offline due to excessive vibrations. Power was restored by midmorning. Illinois, Indiana, and Kentucky state highway crews investigated if any roads or bridges were damaged in the area. Cracks were reported on U.S. Route 51 near Cairo at the state's southern tip. No roads were reported to be damaged in Kentucky, but inspections were being conducted in the Louisville, Paducah, and Henderson districts, according to the Kentucky Department of Transportation.


Aftershocks

More than 250
aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousand ...
s ranging in magnitude from 0.7 to 4.6 were documented in the month following the mainshock, including the largest, which occurred later in the morning. The other stand-out shocks in the sequence were the M4 event on April 21, an M4.2 event on April 25, and a M3.4 shock on June 5 CDT.


Response

Many precautionary measures were taken, including several evacuations. All Vincennes University dormitories were evacuated as a precaution, but no damage was discovered and students were allowed to return after about 45 minutes. A coal mine in
Gibson County, Indiana Gibson County is a county in the southwestern part of the U.S. state of Indiana. As of the 2010 United States Census, the population was 33,503. The county seat is Princeton. History In 1787, the fledgling United States defined the Northw ...
, was also evacuated, but miners returned to work shortly afterwards. The Gibson County
9-1-1 , usually written 911, is an emergency telephone number for the United States, Canada, Mexico, Panama, Palau, Argentina, Philippines, Jordan, as well as the North American Numbering Plan (NANP), one of eight N11 codes. Like other emergency nu ...
system was briefly knocked offline due to a flood of calls, but after about 15 minutes, service was restored.


See also

* List of earthquakes in 2008 * List of earthquakes in Illinois *
List of earthquakes in the United States The following is a list of notable earthquakes and tsunamis which had their epicenter in areas that are now part of the United States with the latter affecting areas of the United States. Those in ''italics'' were not part of the United States whe ...


References


Further reading

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External links


Seismographic Readings for this specific earthquake
– Illinois State Geological Survey
Seismographic Readings for 15:15 (UTC) aftershock
– Illinois State Geological Survey
Lawrence County E911 Security Camera Video of QuakeApril 18, 2008, Mt. Carmel, Illinois: Magnitude 5.2 Earthquake and Aftershocks
– Illinois State Geological Survey
5.2 earthquake rattles skyscrapers, nerves across Midwest
– Associated Press
An Earthquake Rattles the Midwest
– '' The New York Times'' {{DEFAULTSORT:Illinois Earthquake, 2008 2008 earthquakes 2008 natural disasters in the United States Geology of Illinois Southwestern Indiana Earthquakes in the United States Natural disasters in Illinois April 2008 events in the United States 2008 in Illinois 2008 in Indiana