The biggest threat of a major earthquake in Ohio does not come from any quake zone or fault line in Ohio. It comes from the New Madrid fault in southeastern Missouri.
In 1811 and 1812 the fault was the epicenter of a series of earthquakes in the magnitude 7 and 8 range. It toppled chimneys in Cincinnati and was strongly felt throughout Ohio.
In Zanesville, which was serving as the state capital at the time, the legislature was in session when one of the tremors was felt. Accounts of the time include descriptions of the cupola of the courthouse swaying, and legislators jumping out of the first-floor windows to get out of the building.
The Mississippi River was said to have temporarily reversed course.
If a quake of that size hit the same area today, with a city Memphis so close to the epicenter, the results could be devastating.
Earthquakes can affect water wells in Ohio. According to the Division of Geological Survey, quakes have been known to dislodge sand and plug well screens in water wells, or dislodge plugs and improve water flow.
Production spikes have been reported in oil and gas wells as a result of earthquakes. And very large quakes, even though very far away, have caused water tables to temporarily rise or fall. This happened during the 7.9 magnitude earthquake at Denali, Alaska on Nov. 3, 2002.