The Atlantic article seems to provide the best answers to this question with the admission that experts aren't really sure about all possible faults (see quotes).
"Large intra-plate earthquakes, when they disappear on one fault zone, tend to pop up where no one's looking."
"No one really knows how intra-plate earthquakes work. And no one really knows what on earth is going on down there deep underground."
"In Nepal, the country's earthquake hazard map showed the two ends of the country glowing with seismic hazard and a placid interior. Last April an enormous quake struck this unremarkable center of the country and killed more than 8,000 people."
"In most cases these earthquakes are on unmapped faults. A lot of times the way you find a fault in the mid-continent is that you get a big earthquake on it and then you go out and say, 'Oh gee, there's a fault there.'"
— Northwestern University seismologist Seth Stein
TOP 8 SEARCH RESULTS ...
Illinois officials urge earthquake awareness - Chicago Tribune
https://www.chicagotribune.com/news/ct-earthquake-illinois-0206-20150206-story.html
Feb 6, 2015 - In April of that year, a 5.2-magnitude earthquake with an epicenter in southern West Salem, Ill., hardly left a mark but its shaking was felt in 14 states. It is considered the most significantearthquake Illinois endured since 1968, when a 5.3 quake caused more damage to buildings but no injuries.
https://www.chicagotribune.com/news/ct-earthquake-illinois-0206-20150206-story.html
Feb 6, 2015 - In April of that year, a 5.2-magnitude earthquake with an epicenter in southern West Salem, Ill., hardly left a mark but its shaking was felt in 14 states. It is considered the most significantearthquake Illinois endured since 1968, when a 5.3 quake caused more damage to buildings but no injuries.
Is it possible for earthquakes to occur in Chicago? - Quora
https://www.quora.com/Is-it-possible-for-earthquakes-to-occur-in-Chicago
Mar 21, 2017 - While Chicago is very unlikely to be the epicenter of a quake, the Midwest is more seismically active than most people realize. ... And there have been several smaller earthquakes in recent years that have been felt in Chicago. It's really weird to feel the floor suddenly "roll."
Illinois Among States With Highest Risk for Earthquakes - NBC Chicago
https://www.nbcchicago.com/weather/stories/Illinois-Among-States-With-Highest-Risk-for-Earthquakes-267674671.html
Jul 18, 2014 - U.S. Geological Survey updated its national seismic hazard maps for the first time since 2008. ... A new federal earthquake map dials up the shaking hazard just a bit for about one-third of the United States, including Illinois, and lowers it for one-tenth. ... Illinois is among 16 states …
Is Middle America Due For a Huge Earthquake? - The Atlantic
https://www.theatlantic.com/science/archive/2016/06/the-great-middle-american-earthquake/486623/
Jun 23, 2016 - Indeed, the USGS earthquake hazard map of the United States, might ..... about the lithosphere—and it's easy when you live in Chicago—is, ...
1968 Illinois earthquake - Wikipedia
https://en.wikipedia.org/wiki/1968_Illinois_earthquake
The 1968 Illinois earthquake (a "New Madrid event") was the largest recorded earthquake in .... This could cause potentially high damage in the Chicago metropolitan area which has a population near ... Scientists anticipating a future earthquake suggest the Wabash Valley Fault as a possible source, calling it "dangerous".
Geology · Damage · Response · Future threats
List of earthquakes in Illinois - Wikipedia
https://en.wikipedia.org/wiki/List_of_earthquakes_in_Illinois
The following is a list of earthquakes in Illinois. Contents. 1 Earthquakes; 2 See also; 3 Notes; 4 References; 5 External links. Earthquakes[edit]. Date, Area ...
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New Madrid Seismic Zone - Wikipedia
https://en.wikipedia.org/wiki/New_Madrid_Seismic_Zone
The New Madrid Seismic Zone sometimes called the New Madrid Fault Line, is a major seismic ...Earthquakes that occur in the New Madrid Seismic Zone potentially threaten parts of eight .....Chicago: University of Chicago Press, 2013.
Missing: possible | Must include: possible
earthquake risk - ABC7 Chicago
https://abc7chicago.com/archive/7270098/
Feb 15, 2010 - What caused Wednesday's earthquake near Chicago, Illinois? And is it likely to happen again?