When it comes to earth-shaking experiences, Californians aren’t the only ones who feel the earth move beneath their feet. Every year, small earthquakes rattle along buried fault lines in Ohio, particularly in the western and northeastern portions of the state.
While most of us never notice these minor jolts in the earth, sensitive equipment in strategic locations around Ohio is recording every shift and shake that occurs deep beneath the surface of the Buckeye State.
Known as seismographs, the sensitive equipment records underground waves of energy generated by earthquakes. Most recently, these instruments picked up two earthquakes that rumbled through northeast Ohio on consecutive Fridays in January. The first occurred January 6, and registered 2.3 in magnitude as it gently shook the ground beneath Mentor-on-the-Lake, just east of Cleveland in Lake County. The second quake, a 2.6 magnitude, rolled through the same area on January 13. Preliminary data indicate the two earthquakes were actually centered beneath Lake Erie, about nine miles off shore.
Ohio is one of only a few states to have a network of seismograph stations that continuously monitor ground motion to detect and locate local and regional earthquakes. These 25 volunteer stations are located at colleges, universities, and institutions around Ohio, such as the Cleveland Museum of Natural History and Alum Creek State Park.
The instruments are part of the Ohio Seismic Network (or OhioSeis), and are so sensitive to motion that they were able to detect seismic waves from the December 2004 Indian Ocean that created the devastating tsunami.
Geologist Michael Hansen, coordinator of OhioSeis, hopes that scientists will one day be able to use the information gathered by the Ohio seismographs to better understand seismic risk in the Buckeye State.
“Most of the earthquakes measured in Ohio are quite small, feeling something like the rattle from a large truck passing down the street,” Hansen says. “But these small tremors are important to scientists because they occur more frequently. They are valuable tools for helping to identify active seismic areas and the location of faults that may periodically produce larger, potentially damaging earthquakes.”
A look at the Catalog of Ohio Earthquakes on the OhioSeis web site might make you think that our state is encountering more and more earthquakes in recent years. In reality, it’s just that we’ve become better at detecting them, Hansen says. Ohio Seismic Network was begun in 1999, and before that time earthquake data for Ohio was not as readily available nor as reliable.
During 2005, OhioSeis recorded a total of six earthquakes in the state, ranging in strength from 2.0 to 2.5. All but one of these occurred in the northeastern part of the state. According to data from OhioSeis, our state averages about five earthquakes of about 2.0 in magnitude every year. Ohio’s most seismically active regions are northeast Ohio along Lake Erie in Lake and Ashtabula counties, as well as western Ohio, including Shelby and Auglaize counties.
Damage to grocery store in Anna, Ohio in 1937. V.C. Stechshulte, S.J.
J. B. Macelwane archives, Saint Louis University
The largest earthquake known to have occurred within Ohio's borders struck on March 9, 1937, in western Ohio's Shelby County ? measuring 5.4 in magnitude. Residents of the Village of Anna reported tipped chimneys, twisted church organ pipes and a school building damaged so badly it had to be torn down.
You can see a list of Ohio’s earthquakes that registered 2.0 or greater by visiting ohiodnr.com/OhioSeis then scroll down and click on Catalog of Ohio Earthquakes.
One reason we have earthquakes in our state today is that about one billion years ago, land that would one day become Ohio was at the intersection of two great crustal plates that collided. As a result, large blocks of fractured rock - a.k.a. faults - lay buried deep beneath Ohio. As the earth’s plates continue to slowly move, pressure builds up along these ancient faults, causing them to “slip” and generate an earthquake.
Most faults in Ohio are not well known and not visible at the surface. Those who study earthquakes speculate that active seismic zones in western Ohio could generate an earthquake with a magnitude of between 6.5 and 7.0, and the northeastern seismic zone could generate an earthquake with a magnitude of between 6.0 and 6.5.
However, at this time, there is no evidence that Ohio has experienced such large earthquakes in the last 10,000 years, making it unlikely a quake of such size will occur any time soon ? at least not in our life time!
Take time to explore the Ohio Seismic Network web page at ohiodnr.com/OhioSeis, where you can learn more about earthquakes here in Ohio and around the world.