Philadelphia, Pennsylvania – A rare Midwest earthquake early Tuesday, Jan. 20, is now drawing heightened attention across Pennsylvania and New York as a powerful surge of Arctic air drives temperatures sharply lower, creating conditions that could lead to frost quakes across the Mid-Atlantic.
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 rapidly followed.
As the deep freeze expands east into Pennsylvania and New York, 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 western and central Pennsylvania and much of upstate New York, including Pittsburgh, Erie, Harrisburg, Scranton, Albany, Syracuse, Rochester, and Buffalo, may be more susceptible as temperatures plunge following recent rain or snow. Even interior sections of the Hudson Valley and northern New Jersey border communities could see isolated incidents. Frost quakes are shallow and localized but can crack pavement, foundations, and underground utilities.
Emergency officials stress 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.
