Hydraulic fracturing linked to earthquakes in Ohio

October 14, 2014

Hydraulic fracturing triggered a series of small earthquakes in 2013 on a previously unmapped fault in Harrison County, Ohio, according to a study published in the journal Seismological Research Letters.

Nearly 400 small earthquakes occurred between Oct. 1 and Dec. 13, 2013, including 10 "positive" magnitude , none of which were reported felt by the public. The 10 positive magnitude earthquakes, which ranged from magnitude 1.7 to 2.2, occurred between Oct. 2 and 19, coinciding with hydraulic fracturing operations at nearby wells.

This series of earthquakes is the first known instance of seismicity in the area.

Hydraulic fracturing, or fracking, is a method for extracting gas and oil from shale rock by injecting a high-pressure water mixture directed at the rock to release the gas inside. The process of hydraulic fracturing involves injecting water, sand and chemicals into the rock under high pressure to create cracks. The process of cracking rocks results in micro-earthquakes. Hydraulic fracturing usually creates only small earthquakes, ones that have magnitude in the range of negative 3 (−3) to negative 1 (-1).

"Hydraulic fracturing has the potential to trigger earthquakes, and in this case, small ones that could not be felt, however the earthquakes were three orders of magnitude larger than normally expected," said Paul Friberg, a seismologist with Instrumental Software Technologies, Inc. (ISTI) and a co-author of the study.

The earthquakes revealed an east-west trending fault that lies in the basement formation at approximately two miles deep and directly below the three horizontal gas wells. The EarthScope Transportable Array Network Facility identified the first earthquakes on Oct. 2, 2013, locating them south of Clendening Lake near the town of Uhrichsville, Ohio. A subsequent analysis identified 190 earthquakes during a 39-hour period on Oct. 1 and 2, just hours after hydraulic fracturing began on one of the wells.

The micro-seismicity varied, corresponding with the fracturing activity at the wells. The timing of the earthquakes, along with their tight linear clustering and similar waveform signals, suggest a unique source for the cause of the earthquakes—the hydraulic fracturing operation. The fracturing likely triggered slip on a pre-existing fault, though one that is located below the formation expected to confine the fracturing, according to the authors.

"As operations explore new regions, more seismic monitoring will be needed since many faults remain unmapped." Friberg co-authored the paper with Ilya Dricker, also with ISTI, and Glenda Besana-Ostman originally with Ohio Department of Natural Resources, and now with the Bureau of Reclamation at the U.S. Department of Interior.

Explore further: USGS says seven small earthquakes shake central Oklahoma

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Water_Prophet
1 / 5 (5) Oct 14, 2014
And another score for the Water_Prophet. I called this one.
aksdad
1 / 5 (4) Oct 14, 2014
A series of small earthquakes that not only don't cause damage but aren't even felt which gradually relieve pressure on a fault is certainly preferable to a large and damaging earthquake to relieve the pressure built up as tectonic plates move.

Who knew that fracking had additional benefits beyond extracting highly useful oil and natural gas? Now if they could just do some fracking under San Francisco and Los Angeles to mitigate their large earthquakes....
Vietvet
5 / 5 (2) Oct 14, 2014
"Who knew that fracking had additional benefits beyond extracting highly useful oil and natural gas? Now if they could just do some fracking under San Francisco and Los Angeles to mitigate their large earthquakes...."

@askdad your ignorance is showing.
norman
not rated yet Oct 14, 2014
I thought I was the only person that thought fracking must relieve the tension already in the earth. Where to experiment? Not San Francisco, not in a high risk area. There may be some highly seismic but remote location in Siberia. Out in the Pacific would be great but the experiment would be difficult.The other time to try may be after a major quake.
Water_Prophet
1 / 5 (4) Oct 14, 2014
@askdad
Your statement is rather obtuse, even for this board. Are you kidding?
If you thought soil erosion was bad for the economy, etc., how about bedrock erosion? It doesn't even pay for itself for another 30 years, if you can count on things not changing in 30 years.
I always say, fracking or some similar idiocy is why we haven't found intelligent life on other planets, they rose their oceans, and fracked their land, and electronics work not at all under water.
alfie_null
5 / 5 (1) Oct 15, 2014
A series of small earthquakes that not only don't cause damage but aren't even felt which gradually relieve pressure on a fault is certainly preferable to a large and damaging earthquake to relieve the pressure built up as tectonic plates move.

By the same logic, it's good the earth is often struck by small meteorites, as that reduces the chance it will ever be struck by a large asteroid. Or, "I'm glad I keep catching colds, as that makes it less likely I'll ever get cancer."

You should seek another avocation. Please leave thinking to the professionals.
antialias_physorg
5 / 5 (1) Oct 15, 2014
A series of small earthquakes that not only don't cause damage but aren't even felt which gradually relieve pressure on a fault is certainly preferable to a large and damaging earthquake to relieve the pressure built up as tectonic plates move.

Who knew that fracking had additional benefits beyond extracting highly useful oil and natural gas?

Wow. That takes the cake as the most stupid reasoning - ever.

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