2008 Illinois earthquake

2008 Illinois earthquake
Green Bay
Kitchener
Omaha
Atlanta
Tuscaloosa
UTC time 2008-04-18 09:36:59
ISC event
USGS-ANSS
Local date April 18, 2008
Local time 4:36 am CST
Magnitude 5.2 Mw  (USGS)
Depth 11.6 km (7 mi)
Epicenter 38°27′N 87°53′W / 38.45°N 87.89°W / 38.45; -87.89Coordinates: 38°27′N 87°53′W / 38.45°N 87.89°W / 38.45; -87.89
Type Strike-slip [1]
Areas affected Midwestern United States
Total damage Limited [2]
Max. intensity VII (Very strong) [1]
Casualties 2 injured

The 2008 Illinois earthquake was one of the largest earthquakes 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 04:36:59 local time on April 18 near West Salem 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 is an area of dispersed seismic activity that encompasses the border areas of Illinois, Indiana, and Kentucky. This broad multi-state 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, grabens, and anticlines.[3]

Earthquake

USGS ShakeMap for the event

Rapid development and expansion of services from the United States Geological Survey was taking place in the 2000s in terms 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.[4]

Felt area

The shock was felt as far west as Omaha, Nebraska, as far south as Atlanta, Georgia,[5] as far east as Kitchener, Ontario[6] and West Virginia,[7] 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.[7]

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 Edward's County Sheriff's department took reports of minor damage in West Salem.[8] Just across the Wabash River in Indiana, Unit 4 at the Gibson Generating Station automatically shut down due to its vibration sensors,[9] and in Princeton, a woman was cut when a crystal figurine was knocked from a shelf in her home.[10] A man had an eye injury at an unknown location, but medical attention was not sought.[11]

In Louisville, Kentucky, some bricks broke off from an older building near downtown.[8] Slightly further away in St. Louis, Missouri, a portion of the South Kingshighway Boulevard viaduct were closed because of loose pieces of concrete, but it was unclear if the debris was related and traffic resumed half an hour later.[12] Several chimneys also collapsed in south St. Louis, and 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. Thirty-five thousand people in St. Louis County were without power because the Labadie Power Station went offline due to excessive vibrations. Power was restored by mid-morning.

Illinois and Kentucky state highway crews were 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.[13] 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.[14]

Aftershocks

More than 250 aftershocks ranging in magnitude from .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, a 4.2 event on April 25, and a M3.4 shock on June 5 CDT.[15]

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, was also evacuated, but miners returned to work shortly afterwards.[16] The Gibson County, Indiana, 9-1-1 system was briefly knocked offline due to a flood of calls, but after about 15 minutes service was restored.[16]

See also

References

  1. 1 2 USGS. "M 5.2 - 11km WNW of Mount Carmel, Illinois". United States Geological Survey. Retrieved September 26, 2017.
  2. ↑ National Geophysical Data Center / World Data Service (NGDC/WDS), Significant Earthquake Database, National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K
  3. ↑ McBride, J. H.; Hildenbrand, T. G.; Stephenson, W. J.; Potter, C. J. (2002), "Interpreting the Earthquake Source of the Wabash Valley Seismic Zone (Illinois, Indiana, and Kentucky) from Seismic-reflection, Gravity, and Magnetic-intensity Data", Seismological Research Letters, Seismological Society of America, 73 (5): 660–663, doi:10.1785/gssrl.73.5.660
  4. ↑ Yang, H.; Zhu, L.; Chu, R. (2009), "Fault-Plane Determination of the 18 April 2008 Mount Carmel, Illinois, Earthquake by Detecting and Relocating Aftershocks" (PDF), Bulletin of the Seismological Society of America, Seismological Society of America, 99 (6): 3413, 3414, Bibcode:2009BuSSA..99.3413Y, doi:10.1785/0120090038
  5. ↑ "Geological survey now registers quake at 5.2". The Southern Illinoisan. 18 April 2008. Retrieved 2008-04-18.
  6. ↑ Canwest News Service (April 18, 2008). "Illinois earthquake rattles southern Ontario". National Post. Archived from the original on April 27, 2008.
  7. 1 2 "Nope, you weren't dreaming". Chicago Tribune. 19 April 2008. Archived from the original on 20 April 2008. Retrieved 2008-04-19.
  8. 1 2 AP (April 18, 2008). "5.2 earthquake rocks the Midwest". ABC7 Chicago. Archived from the original on April 14, 2016.
  9. ↑ http://www.tristate-media.com/articles/2008/04/21/pdclarion/news/news1.txt%5Bdead+link%5D
  10. ↑ "Update: Aftershocks rattle Tri-State Friday". WFIE. Archived from the original on February 19, 2012. Retrieved September 26, 2017.
  11. ↑ Easter, Laura (April 22, 2008). "Residents 'obviously shaken and concerned' by earthquake activity, Colby Rigg says". Daily Republican Register, Tri-State Media.
  12. ↑ Kristen Gosling (April 18, 2008). "Lanes on KingsHighway Viaduct Reopen". KSDK. Archived from the original on January 28, 2013.
  13. ↑ "Strong Aftershock Felt In Midwest". AHN – All Headline News. Archived from the original on 2008-12-02. Retrieved 2008-04-18.
  14. ↑ "Bridge Inspections Underway in Kentucky". WXIX-TV Fox19 News. Archived from the original on 26 April 2008. Retrieved 2008-04-18.
  15. ↑ Herrmann, R. B.; Withers, M.; Benz, H. (2008), "The April 18, 2008 illinois Earthquake: An ANSS Monitoring Success" (PDF), Seismological Research Letters, Seismological Society of America, 79 (6): 830–834, doi:10.1785/gssrl.79.6.830
  16. 1 2 "Significant Earthquake Rumbles Early Friday". WRAY Radio. Archived from the original on July 21, 2010. Retrieved 2008-04-19.

Sources

  • Conder, J. S.; Arciniegas, T. A. (2002), "Conjugate Faulting in the Wabash Valley Fault Zone Exhibited by the 20 November 2012 mb 3.6 Earthquake, a Mt. Carmel Late Aftershock", Seismological Research Letters, Seismological Society of America, 88 (4): 1203–1209, doi:10.1785/0220170021
  • Hartzell, S.; Mendoza, C. (2011), "Source and Site Response Study of the 2008 Mount Carmel, Illinois, Earthquake", Bulletin of the Seismological Society of America, Seismological Society of America, 101 (3): 951–963, Bibcode:2011BuSSA.101..951H, doi:10.1785/0120100222
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