Fracking stories spread across the internet over the last few years. Some say it’s risk-free. Residents in the vicinity, on the other hand, experience serious problems shortly after the process begins. The latest story involves earthquakes shaking Ohioans after fracking wastewater was injected into the ground. Yesterday (March 9, 2012), Ohio introduced regulations to the industry as a result of this phenomenon.
Fracking-caused Earthquakes Near Youngstown, Ohio
Fracking actually indirectly caused earthquakes near Youngstown. However, the real cause raises questions about injecting fluids into the earth. First, let me give you a little background about what happened:
- Cause: On Friday, March 9, 2012, Ohio state regulators indicated that eleven earthquakes throughout 2011 were induced by injection of gas-drilling wastewater into the earth (Carr Smith 2012).
- Earthquake Start: The earthquakes started in March 2011 (Ohio Seismic Network 2012a).
- Earthquake Strength: Thus far, the strongest magnitude measured 4.0 mbLg on December 31, 2011 (Ohio Seismic Network 2012a; from 2012b)
- mbLg is a measurement of the short-period body wave (following mbLg info from McCalpin 2009)
- mb stands for short-period (McCalpin 2009:1)
- Lg surface waves are generally the largest, regionally-recorded seismic waves in the eastern and central United States and parts of Canada (Sykes et al. 2008:1700)
- Last Earthquake as of March 10, 2012: So far, the last tremor shook Youngstown on January 2012 (Ohio Seismic Network 2012a)
Danger Level of Ohio Earthquakes:
- Shaking: The tremors have shaken peoples homes, possibly disrupting lives and causing damage there (Ohio Seismic Network 2012b).
- Liquefaction: Liquefaction occurs in saturated soils. Water pressure increases, which moves soil particles away from each other. Since the soil grains are moving, they can no longer bind together. This decreases their strength and stiffness.
- Danger: Liquefaction is dangerous because the soils can no longer support the weight of what is on top of it. It shakes into a liquid, and acts as such. When this occurs, buildings can sink into the ground.
- Liquefaction Magnitude (E. U.S.): In the eastern United States, liquefaction generally has occurred at magnitude 6.0 or higher (Hansen 1994:7)
- Liquefaction Magnitude (General): In general, liquefaction occurs at magnitudes of 5.5 or higher (Hansen 1994:7)
- Ohio Earthquakes Not At Liquefaction Magnitude: Thus far, we only have a magnitude 4 earthquake. It is good measures are being taken to keep it that way
Ohio Earthquake History
Compared to several places in the country, Ohio doesn’t experience a lot of earthquakes. However, there are a few, which increases risk to this wastewater-injection method of the gas drillers.
- 6,100 years ago: the last earthquake in Ohio above magnitude 7 (Hansen 1994:7)
- March 9, 1937: earthquake in western Ohio seismic zone estimated at 5.5 (this was the largest of felt earthquakes recorded since 1875 [Hansen 1994:7])
- 1986: an earthquake in northeastern Ohio measured magnitude 5.0 (Hansen 1994)
Ohio Earthquake-specific Links:
Seismic Liquefaction Dangers Link
Carr Smith, Julie
2012 After Quakes, Ohio Plans Tough Gas-Drilling Rules. Atlanta Journal Constitution (published online March 9, 2012 at 5:46 pm). Electronic document, http://www.ajc.com/news/nation-world/after-quakes-ohio-plans-1379190.html, accessed March 10, 2012.
Hansen, Michael C.
1994 Searching for Ancient Earthquakes. Ohio Geology (1994:6-7). Electronic document, http://www.dnr.state.oh.us/Portals/10/pdf/newsletter/Fall94.pdf, accessed March 10, 2012.
McCalpin, James P.
2009 Earthquake Magnitude Scales, Appendix 1. In Paleoseismology, edited by James P. McCalpin. Academic Press, an imprint of Elsevier, Burlington, Massachussetts. Electronic document (just the Appendix), http://www.elsevierdirect.com/companions/9780123735768/casestudies/01~Appendix_1.pdf, accessed March 10, 2012.
Ohio Seismic Network
2012a Recent Ohio/Regional Earthquakes. OhioSeis: Ohio’s Earthquake Monitoring Network (last updated February 23, 2012). Ohio Seismic Network. Ohio Department of Natural Resources Division of Geological Survey. Electronic document, http://www.dnr.state.oh.us/tabid/8144/Default.aspx, accessed March 10, 2012.
2012b Earthquake, Youngstown, Mahoning County, December 31, 2011. OhioSeis: Ohio’s Earthquake Monitoring Network (last updated January 4, 2012). Ohio Seismic Network. Ohio Department of Natural Resources Division of Geological Survey. Electronic document, http://www.dnr.state.oh.us/tabid/23729/Default.aspx, accessed March 10, 2012.
Sykes, Lynn R., John G. Armbruster, Won-Young Kim, and Leonardo Seeber
2008 Observations and Tectonic Settings of Historic and Instrumentally Located in the Greater New York City – Philadelphia Area. Bulletin of the Seismological Society of America 98(4):1696-1719. Electronic document, http://www.earth.columbia.edu/sitefiles/file/pressreleases/1696.pdf, accessed March 12, 2012.
Fracking-caused Earthquakes in Ohio: Background by shari Maria Silverman is licensed under a Creative Commons Attribution 3.0 Unported License.