Indianapolis, Indiana – A rare Midwest earthquake early Tuesday, Jan. 20, is now raising awareness across the Ohio Valley as Arctic air pours into Indiana and Kentucky, sending temperatures sharply lower and creating conditions that could lead to frost quakes across the region.
According to the U.S. Geological Survey, a 3.5 magnitude earthquake struck central Illinois shortly before 2 a.m. Tuesday, Jan. 20, centered about 35 miles south of Springfield near Ohlman. The shallow quake was felt across a wide portion of Illinois, with thousands reporting shaking, rumbling, and rattling windows before sunrise. While no damage was reported, seismic events of this size are uncommon in the Midwest, making the timing notable as extreme cold quickly followed.
As the deep freeze spreads through Indiana and Kentucky, geologists say rapid temperature drops associated with this Arctic outbreak can trigger frost quakes, also known as cryoseisms. These occur when moisture in the ground freezes suddenly, causing soil and rock to contract and fracture. The result can be a loud boom or brief shaking that may feel similar to a small earthquake, often occurring overnight or before dawn.
Areas across the Ohio Valley, including Indianapolis, Bloomington, Evansville, Louisville, Lexington, Bowling Green, and communities along the Ohio River, may be more susceptible as temperatures plunge following recent rain or snow. Frost quakes are shallow and localized but can crack pavement, foundations, and underground utilities, particularly near roads, older structures, and buried pipes.
Emergency officials emphasize that frost quakes are not tied to fault lines and do not signal larger earthquakes. Residents are encouraged to remain alert during the coldest overnight hours, inspect property if shaking or loud booms are noticed, and report ground movement to local authorities or the USGS. With dangerous cold expected to persist through midweek, additional advisories or alerts may follow.
