Magnitude 5.4 Mw Max. intensity VII - Very strong Depth 11,600 m | Areas affected United States Casualties 2 injuries Date 18 April 2008 | |
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Similar 1909 Wabash River eart, 2003 Alabama earthquake, 1993 Scotts Mills earthquake, 1663 Charlevoix earthquake, 1872 Lone Pine earthquake |
The 2008 Illinois earthquake was one of the largest earthquakes ever recorded in the state of Illinois, measuring a magnitude of 5.4. It occurred at 4:37am CDT (9:37:00 UTC) on April 18 within the Wabash Valley Seismic Zone at a depth of 11.6 km. It was centered near West Salem, Illinois and Mount Carmel, Illinois (the affected area is west of Terre Haute, Indiana and Vincennes, Indiana; east of St. Louis, Missouri; and northwest of Evansville, Indiana), specifically 38.450°N, 87.890°W, and felt as far as 450 miles (724 km) away. Tremors were felt as far west as Nebraska and Kansas City, as far south as Atlanta, 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 tremor to propagate further.
Contents
The earthquake epicenter was located in the Wabash Valley Seismic Zone, which is adjacent to the more famous New Madrid Seismic Zone.
Damage
Emergency response
Many precautionary measures were taken after the initial quake, 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, was also evacuated after the earthquake, but miners returned to work shortly afterwards.
The Gibson County, Indiana, 9-1-1 system was briefly knocked offline due to a flood of calls resulting from the earthquake, but after about 15 minutes service was restored.
Aftershocks
A week after the main earthquake, the USGS recorded a total of 26 aftershocks ranging in magnitude from 1.0 to 4.6. The biggest aftershock occurred at 10:14am CDT (15:14 UTC), on April 18; it was a magnitude 4.6, and also centered near West Salem, just north of the original quake. An aftershock with a magnitude of 4.0 (initially reported as 4.5) was felt three days later on April 21, at 12:38am CDT (05:38 UTC), centered northwest of Mt. Carmel, Illinois. A 3.7 aftershock struck on Friday, April 25 around 17:30 GMT (12:30 p.m. CDT). A 3.3 aftershock struck on Thursday, May 1 around 5:30 GMT (12:30 a.m. CDT). A 3.6 aftershock struck on Thursday, June 5 around 2:13 a.m. local time.
Earthquake on TV
Several television stations were live on-air when the quake hit. CBS 8 WISH-TV in Indianapolis, NBC 14 WFIE in Evansville and WAVE 3 and WHAS 11 in Louisville were doing local news broadcasts when the tremors hit.
Tremors of the magnitude 4.6 aftershock were also caught on camera during a taped interview with the Indiana Department of Transportation in Vincennes, Indiana, as the interviewer asked about the magnitude 5.4 earthquake. It was later broadcast on the Wabash Valley's local news station WTWO's Live at Five broadcast.