April 18, 2008, Mt. Carmel, Illinois: Magnitude 5.2 Earthquake and Aftershocks
At 4:37 a.m. on April 18, 2008, Illinois experienced a 5.2 magnitude earthquake. The earthquake was felt in 18 states. The epicenter of the earthquake was located about six miles northwest of Mt. Carmel, Illinois, and was located in the Wabash Valley Seismic Zone. This area was the location of previous magnitude 5 earthquakes in 1968 and 1987. The 1968 magnitude 5.3 earthquake was the largest recorded in the central United States since 1895. On the day of the quake, members of the Illinois State Geological Survey (ISGS) participated in many roles to provide information to the Governor's Office, Illinois Emergency Management Agency (IEMA), and the public through approximately 20 press interviews and continuous updates to the ISGS Web site. ISGS staff coordinated deployment of portable recording seismographs near the main shock epicenter by representatives of the Center for Earthquake Research and Information, University of Memphis, and Indiana University. The damage in towns within about 30 miles of the earthquake was documented. Over two dozen magnitude 1.0 or greater aftershocks have been recorded, and ISGS staff continue to monitor these events and communicate information to the public.
The ISGS had a staff member at the State Emergency Operations Center in Springfield who helped write several press releases for the Governor's Office and IEMA. Text was also provided for the IEMA and Homeland Security Web sites. Additionally, ISGS staff, the IEMA director, and a representative from the Department of Insurance participated in the State's press conference. Historical earthquake information about the area of the earthquake and expectations for aftershocks were also communicated to the representatives in the State Emergency Operations Center.
Damage in Illinois was recorded by two ISGS geologists on the day of the main shock. The geologists documented the nonstructural damage to chimneys, parapets, grave markers, and television antennae in many towns in roughly a 30-mile radius of the epicenter. They documented one building where brick walls fell inward, causing the apartment building to be condemned.