This is the Biggest and Most Damaging Earthquake in Illinois History


Many people don’t know that Illinois has a lot of earthquakes, but the state has had some big ones in the past. On the Richter scale, the strongest one was on November 9, 1968, and it was 5.4 on the scale. It was felt in 23 states and some parts of Canada. In Illinois and nearby states, it did some small damage.

The Hamilton County Earthquake of 1968

The 1968 earthquake happened near the town of Dale in Hamilton County, Illinois. This is about 120 miles east of St. Louis, Missouri. An earthquake happened 25 kilometers below the surface. It was caused by a dip-slip faulting, which means that one block of rock moved up and down in relation to another block of rock along a fault line.

People in Boston, Massachusetts, and Atlanta, Georgia, could feel the quake. It was the biggest quake to hit the central United States since the New Madrid earthquakes in 1811 and 1812, which were thought to have magnitudes of 7.0 or higher. With a magnitude of 5.1, the Aurora earthquake in 1909 was the biggest one ever recorded in Illinois. The 1968 quake was bigger than that one.

Buildings, chimneys, windows, and water pipes in Illinois and nearby states were damaged by the 1968 earthquake, but no one was hurt or killed. Some homes and schools in southern Illinois were cracked or moved, which was the worst of the damage. In some places, the earthquake also caused floods, liquefaction, and cracks in the ground.

The Rate of Earthquakes in Illinois

Illinois is in the stable continental area of the North American Plate. This means that it is not near the busy plate boundaries, which are where most earthquakes happen. The New Madrid Seismic Zone (NMSZ) and the Wabash Valley Seismic Zone (WVSZ), on the other hand, both have an impact on Illinois.

The NMSZ is a complicated network of lines that stretches from northeastern Arkansas to southern Illinois. It is what caused the very strong earthquakes that happened in 1811 and 1812 in the United States. The NMSZ is still going strong and causes hundreds of small earthquakes every year. Some of these can be felt in Illinois.

The WVSZ is a smaller and less active seismic zone that goes from the southeast corner of Illinois to the southwest corner of Indiana along the Wabash River valley. The 2008 Mount Carmel earthquake, which had a magnitude of 5.4 and was the biggest in Illinois in recent years, is thought to have started in the WVSZ and continued into the NMSZ.

What Will Happen with Earthquakes in Illinois?

The USGS says that there is a 7–10% chance that an earthquake of magnitude 6 or greater will happen in the NMSZ in the next 50 years. There is a 25–40% chance that an earthquake of magnitude 6 or greater will happen in the WVSZ during the same time period. These earthquakes could do a lot of damage and make life difficult in Illinois and other states, especially in cities with older buildings that are more likely to collapse.

Illinois has accepted the International Building Code, which has seismic design rules for both new buildings and renovations. This is to get ready for the possible effects of earthquakes. The Great Central U.S. ShakeOut is another event that Illinois takes part in. It is a yearly earthquake drill that tries to teach and raise awareness among the public and first responders. The state also backs the creation and enhancement of systems that track and warn of earthquakes, like the Advanced National Seismic System and the ShakeAlert Earthquake Early Warning System.


According to the data, Illinois has been the site of several notable earthquakes throughout its history, most notably the 1968 Hamilton County earthquake, which was the state’s largest and strongest. The data additionally elucidates the genesis and consequences of these seismic events, in addition to the seismic zones that exert an impact on the area. Furthermore, the data underscores the potential hazards and difficulties that forthcoming seismic events might present for Illinois and other states, as well as the proactive actions being undertaken to safeguard the populace and infrastructure.

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