For many years California has been considered by most as the earthquake capital of the US... that is until this year. Who do you think has surpassed California for the most earthquakes of 3.0 magnitude or larger in the United States? I would have never guessed!
The answer is Oklahoma! According to the USGS, in June, Oklahoma moved passed California for the most quakes of magnitude 3.0 or larger in the US. Just today alone, Oklahoma has had two 3.2 earthquakes clustered around the Oklahoma City metro area.
Why Is Oklahoma The Earthquake Capital Of The US Now?
The USGS addressed this question in may in a very interesting article...
The rate of earthquakes in Oklahoma has increased remarkably since October 2013 – by about 50 percent – significantly increasing the chance for a damaging magnitude 5.5 or greater quake in central Oklahoma.
A new U.S. Geological Survey and Oklahoma Geological Survey analysis found that 145 earthquakes of magnitude 3.0 or greater occurred in Oklahoma from January 2014 (through May 2; see accompanying graphic). The previous annual record, set in 2013, was 109 earthquakes, while the long-term average earthquake rate, from 1978 to 2008, was just two magnitude 3.0 or larger earthquakes per year. Important to people living in central and north-central Oklahoma is that the likelihood of future, damaging earthquakes has increased as a result of the increased number of small and moderate shocks.
Oklahoma’s heightened earthquake activity since 2009 includes 20 magnitude 4.0 to 4.8 quakes, plus the largest earthquake in Oklahoma’s history – a magnitude 5.6 earthquake that occurred near Prague on Nov. 5, 2011. The 2011 Prague earthquake damaged a number of homes and the historic Benedictine Hall at St. Gregory's University in Shawnee. Prior to the 2011 Prague earthquake, the largest earthquake of Oklahoma’s history was a magnitude 5.5 earthquake that occurred in 1952 near El Reno and damaged state buildings in Oklahoma City.
USGS statistically analyzed the recent earthquake rate changes and found that they do not seem to be due to typical, random fluctuations in natural seismicity rates. Significant changes in both the background rate of events and earthquake triggers needed to have occurred in order to explain the increases in seismicity, which is not typically observed when modeling natural earthquakes.
The analysis suggests that a likely contributing factor to the increase in earthquakes is triggering by wastewater injected into deep geologic formations. This phenomenon is known as injection-induced seismicity, which has been documented for nearly half a century, with new cases identified recently in Arkansas, Ohio, Texas and Colorado. A recent publication by the USGS suggests that a magnitude 5.0 foreshock to the 2011 Prague, Okla., earthquake was human-induced by fluid injection; that earthquake may have then triggered the mainshock and its aftershocks. OGS studies also indicate that some of the earthquakes in Oklahoma are due to fluid injection. The OGS and USGS continue to study the Prague earthquake sequence in relation to nearby injection activities.
It gets a little more interesting when you look at an article written about a recent string of earthquakes in Ohio. I wrote a blog about the process know as "fracking" and it's link to earthquakes about 3 months ago and it seems the link is likely extended to Oklahoma's elevation to the earthquake capital of the US.
For years we have know that the process of extracting oil or natural gas from the earth could be a problem, research recently has provided a very likely link. The scary part is that it is our region. The link has now officially been made between hydraulic fracturing (known as fracking) and earthquakes. I know some will ask what fracking is so let me explain.
Fracking is a well known mining technique where water mixed with sand/chemicals is injected at a high pressure into the drilled wellbore. The high pressure of the mixture being injected creates small fractures in the ground allowing the solution of water and sand to migrate into the well. Once the liquid is removed from the ground, the small grains of sand or chemicals hold these fractures open allowing the well to reach an equilibrium pressure and the hydrocarbons to migrate to the drilled hole called the bore. This technique has given wells a longer life and made it much easier to remove the oil or gas inside.
The problem is the technique is now linked to earthquakes. Not just a couple, but the USGS estimates a 6 fold increase from 2000-2011! To make things worse, it appears there has been a link to the March 11-12 earthquakes in eastern Ohio near Youngstown (magnitude 3.0). Here is what the Ohio Department of Natural Resources is saying...
COLUMBUS, OH – Today Ohio Department of Natural Resources (ODNR) Director James Zehringer announced new, stronger permit conditions for drilling near faults or areas of past seismic activity. The new policies are in response to recent seismic events in Poland Township (Mahoning County) that show a probable connection to hydraulic fracturing near a previously unknown microfault.
New permits issued by ODNR for horizontal drilling within 3 miles of a known fault or area of seismic activity greater than a 2.0 magnitude would require companies to install sensitive seismic monitors. If those monitors detect a seismic event in excess of 1.0 magnitude, activities would pause while the cause is investigated. If the investigation reveals a probable connection to the hydraulic fracturing process, all well completion operations will be suspended. ODNR will develop new criteria and permit conditions for new applications in light of this change in policy. The department will also review previously issued permits that have not been drilled.
“While we can never be 100 percent sure that drilling activities are connected to a seismic event, caution dictates that we take these new steps to protect human health, safety and the environment,” said Zehringer. “Not only will this reasonable course of action help to ensure public health and safety but it will also help us to expand our underground maps and provide more information about all types of seismicity in Ohio.”
“ODNR’s directives are a sensible response to a serious issue that regulators across the country are closely examining,” said Gerry Baker, Associate Executive Director of the Interstate Oil and Gas Compact Commission. “IOGCC is pleased to work with Ohio and other states to share scientific data to better understand the nature of these occurrences.”
“These additional standards add even more strength to Ohio’s already comprehensive regulatory program,” said Mike Paque, Executive Director of the Groundwater Protection Council. “State regulators are taking an aggressive lead in tackling tough and complicated oil and gas issues and ODNR is no exception.”
More than 800 wells have been drilled in Ohio’s Utica and Marcellus shale play, including as many as 16,000 hydraulic fracturing stages from those wells. Regarding the seismic events in Poland Township, Mahoning County, ODNR geologists believe the sand and water injected into the well during the hydraulic fracturing process may have increased pressure on an unknown microfault in the area. Further hydraulic fracturing at the site is suspended but the company will be permitted to recover resources from five of the previously drilled wells located on the pad. This is also expected to have the beneficial effect of reducing underground pressure and decreasing the likelihood of another seismic event.
Under ODNR’s lead, Ohio has joined a consortium of state regulators dedicated to learning more about seismic activity, especially as it relates to oil and gas activity. The members of this consortium are currently working with the Interstate Oil and Gas Compact Commission and Groundwater Protection Council to share information and knowledge. The working group also hopes to draw upon current and future research to develop common procedures for how to monitor for seismic activity and respond if activity occurs.
The Ohio Seismic Network, coordinated by ODNR and operated by various partners, began recording seismic events in 1999. Before that time, the recording of seismic events varied from distant machines and felt reports. Ohio has a history of seismic activity, and since the network has established, Ohio has experienced 109 events greater than 2.0 magnitude. Data from the Ohio Seismic Network will be used as part of our new application review process.
It is crazy that man made activity could first of all cause earthquakes, but secondly elevate a state to the quake capital of the country. It does appear that this is exactly what is happening.
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