The early hours of February 22 were typical for a Sunday morning in rural Highland County. Absent the typical weekday rush, most residents of the area in rural southwestern Ohio were still sleeping, or perhaps up and enjoying that first cup of coffee or starting to get ready for chores or church.
But then, a little before 6 a.m., something happened that was not at all typical. Dozens of posts and comments on social media forums described a sound like thunder, rattling windows, and items falling from shelves. Turns out, the shaking that caused the early wake-up call was an earthquake — a mild 2.5 temblor deep below the earth’s surface a couple of miles or so east of Hillsboro.
Ohio, of course, is not immune from seismic activity. There are several long-dormant fault zones known as remnant strain faults underneath the Buckeye State, according to Mike Brudzinski, a geology professor and earthquake expert at Miami University in Oxford — and some of those, he says, have energy built up in them like a cocked gun.
But knowing which faults are ready to fire is still out of scientific reach.
Ohio is not immune from seismic activity. There are several long-dormant fault zones known as remnant strain faults underneath the Buckeye State.
“Over long periods of time, small changes in stress in the earth can tip a fault over the edge,” Brudzinski says. “How many cocked guns are left and how many faults are really primed? There is no way to know; we really can’t anticipate when and where they will occur. Our ability to forecast earthquakes is not great.”
While Hillsboro may have been the site of the most recent shaker, Brudzinski says that Anna, a town of 1,500 people between Dayton and Lima, is the earthquake epicenter of the Buckeye State.
Anna, which sits atop the Anna-Champaign Seismic Zone, a fault deep below the surface, frequently experiences small trembles — but also was the site of two of the largest earthquakes in Ohio’s recorded history (see list, opposite page). “You might be able to make the case that for magnitude 5.0-size events, Anna is the only place in the state,” Brudzinski says.
But it definitely isn’t the only place that shakes. Magnitude 3.0 events are a regular occurrence northeast of Cleveland, for example, though many of those are related to fracking rather than naturally occurring faults in the earth’s crust.
The biggest earthquake threat to folks in Ohio, in fact, actually comes from outside the state. The New Madrid Seismic Zone, which runs through Missouri and Illinois, spurred magnitude 7.0 earthquakes in the early 1800s that were felt as far away as Boston. Brudzinski says a hypothetical 7.5-plus event in the northeast part of that zone today likely would cause widespread disruption over the entire eastern part of the country, including much of Ohio. Damage would be greater than even a 6.0 event centered in Anna — where the damage would still be significant, but likely would be more contained to the immediate area.
Brudzinski says there is a good chance most Ohioans will not experience an earthquake in their lifetime. He says that a “big one” could happen here, “but it could happen in a lot of other places too.”
A deep rumbling accompanied the tremor, and those living on traffic arteries were inclined at first to believe the noise was caused by passing trucks. Because of the quietness of the hour, the quake was noticed by many more persons than the one which shook Ohio the previous Tuesday. Tumbling brick chimneys and shattered glass awakened residents of Anna, where the latest quake probably centered, similar to that of last week, seismologists reported."
— The Bluffton News, March 11, 1937
EIGHT NOTABLE OHIO EARTHQUAKES
Anna (Shelby County), March 9, 1937, magnitude 5.4. The largest earthquake in Ohio history. Caused severe damage, including cracked buildings, toppled chimneys, and structural issues.
Anna (Shelby County), March 2, 1937, magnitude 5.0. Occurred one week before the larger quake. Damaged churches and chimneys throughout the area.
LeRoy Township (Lake County), Jan. 31, 1986, magnitude 5.0. Struck near Cleveland in Lake Erie. Felt in 10 states and southern Canada; caused broken windows and cracked plaster.
Lima (Allen County), Sept. 19, 1884, magnitude 4.8. Significant for the late 19th century.
Portsmouth (Scioto County), May 17, 1901, magnitude 4.2. Dislodged bricks from chimneys and cracked windows.
Crooksville (Perry County), June 20, 1952, magnitude 3.9. Caused minor to moderate damage.
Pomeroy (Meigs County), Nov. 5, 1926, magnitude 3.6. Caused minor to moderate damage around southeastern Ohio.
Youngstown (Mahoning County), Dec. 31, 2011, magnitude 4.0. About 2.5 miles northwest of the city.
