Saturday, August 1, 2009

Injection Induced Earthquakes - NE Ohio

Camp, Mark J.; Roadside Geology of Ohio; Mountain Press, Missoula, Montana, 2006 , 411 pp.

Northeast Ohio Earthquakes page 315

A Jesuit priest, Reverend Frederick L. Odenbach, set up the first seismograph in Ohio in Cleveland in 1900. It was one of the first in the United States. Ohio was not a center of earthquake activity, but seven weak to mild shocks had struck Ashtabula, Cuyahoga, Lake Portage, and Summit Counties in the 1800’s. Father Odenbach’s pioneering work allowed researchers to record about a dozen moderate quakes during the 1900’s. The most notable quake in the area, however, occurred much later, on January 31, 1986, southeast of Painesville. It registered about 5 on the Richter scale. Two people suffered minor injuries; items fell off store shelves in Chardon, Mentor, and Painesville; windows and plaster walls cracked; and area well water reportedly changed color and taste. Portable seismographs placed around the area the day after the main quake recorded at least thirteen aftershocks as high as 2.4 Richter magnitude. The great interest in this quake was probably related to the fact that a nuclear power plant operates in nearby Perry.

Small faults are common in Devonian-age rocks in northeastern Ohio. Other, more ancient ones lie more than a mile below the surface in Precambrian rocks. All these faults experience periodic adjustments, caused by the release of stress or pressure in the subsurface, which are recorded as earthquakes at the surface.

On January 25, 2001, a quake registering 4.6 magnitude rattled the Ashtabula area. This was only one of dozens that had shaken the area since 1987. Injection of waste fluids down a 6,000-foot-deep well into the Cambrian Mt.Simon sandstone from 1987 to 1993 has been linked to this seismic activity. The injected fluids seep along cracks in the sandstone, leading to slips along faults. The faults have been there for hundreds of millions of years and have just come to life in recent years because of artificial lubrication.

Mark J. Camp has a PhD in geology from The Ohio State University.

Bold italics by Jane Staley