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Stations study earthquakes in Ohio

PORTSMOUTH – Ohio can shake, rattle and roll with the best of regions – geologically speaking, that is.

Tuesday, August 14, 2001

PORTSMOUTH – Ohio can shake, rattle and roll with the best of regions – geologically speaking, that is.

Earthquakes in Ohio may not sound, or feel, like the norm but according to geologists the state has its share of quakes.

The latest one to shake Ohioans was in Greenwich, a town about 50 miles from Cleveland. The earthquake, which struck at 6:47 a.m. July 26 measured 2.7 magnitude, not a very disturbing earthquake considering only a few people felt it.

Since 1776, 120 earthquakes have been recorded in the state with 14 of these events causing mild to moderate damage. In 1995, Lawrence County recorded a mild quake that ranged from I to III on the Modified Mercalli scale.

The largest quake to shudder the state was in 1937 in Shelby County. This event was estimated to have had a magnitude of about 5.5, causing damage to structures in the surrounding communities.

The Northwestern portion of the state is home to the most active earthquakes, with the city of Anna holding the right to be called the "Earthquake Capital of Ohio" by seismologists. Since 1875, 40 earthquakes have hit the city.

In order to measure and monitor quakes in the state, Ohio has established a network of seismometers to keep track of the earth’s vibrations. The Ohio Seismic Network has about 22 affiliate sites, with the closest site to Lawrence County at Shawnee State University in Portsmouth.

Geologist and director of the Shawnee site, Dr. Jeffrey A. Bauer, said the station at the Scioto County university is able to detect quakes of about a 5.0 magnitude from across the world. He said the site is also used to study the intricate geological phenomena in the state – research that has not been heavily conducted in the past.

Bauer explained underground faults run across the state, most of them deep beneath the earth’s surface. The depth of the fault line, Bauer explained, is the reason this area doesn’t have evidence of the fault at the surface.

Earthquakes occur at these fault lines which are weaknesses in the in upper crust of the earth. When an amount of strain builds up along the weak spot and the plates slip, an earthquake occurs.

With the equipment in place, Bauer said, earth scientists hope to have a better understanding, and record, of earthquakes that shake the state.