15 miles north of Sharon, Pa. - Magnitude 5 (I know that's not NW Ohio but, if you don't want to look at it, you don't have to!)

June 4, 1990: Hancock/Seneca county line.

This event was also recorded by the University of Michigan's Anna/Lima seismograph network, since abandoned. Two residents called Toledo to report a felt earthquake. Nice clear P and S arrivals, hardly any surface waves.

  July 14, 1992:   North Baltimore

Mostly surface waves, probably a shallow event. No P or S arrivals obvious. This was reported as a felt event by 2 North Baltimore residents, otherwise I might have assumed this was noise.

If citizens report feeling an earthquake within a minute or two of an unusual tracing or ground motion at UTO, I think it safe to conclude that a small earthquake has occurred.  

  October 4, 1992:   West of Bowling Green

 People in west Bowling Green reported hearing a loud explosion or sonic boom. No physical evidence of an explosion has been found, and there were no aircraft in the region that could have caused a sonic boom. UTO recorded this ground motion during that minute, the minute of the "explosion". UTO does not respond to thunder or aircraft noise. I therefore conclude that this was a shallow earthquake. Timing marks do not line up because drum motor was failing - fortunately, it functioned will enough to permit the timing of this unusual ground motion, mostly surface waves.

   October 10, 1993

West of St. John's Jesuit High School, Toledo

Magnitude 2.0

Reported by 3 residents of that neighborhood. This S-P time is consistent with that the distance. This one looks like a microearthquake should look. The coda (tail) of a quarry blast is seen 2 traces under the tremor. Typical cultural noise (truck traffic on campus?) is also visible.

For all seismograms: records are from the short-period vertical system; timing marks are 2.0 seconds in duration and traces are about 2.5 mm apart.

Background shows microseisms recorded on the long-period drum.

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