The Edmond Earthquakes

 WHATS IN THIS BLOG:
• A series of earthquakes in Edmond yesterday.
• The stats on these earthquakes.
• Are earthquakes declining in Oklahoma?
• Other pockets of induced earthquakes in the USA.

Just to clarify: each of my blogs centers on one of three things: (1) Inspiration and Hope, or (2) Science and Energy, or (3) Health and Hiking. Probably too broad a spectrum, but I can’t decide how to narrow it down.

One way to resolve this might be to write alternative blogs more often. I think I’ll try this…. maybe a new blog every few days. My goal for every blog is still to add value to readers.

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Before I jump into this blog, which is about science, I mentioned in Lean On Me about a young woman who cannot drive without hand-controls. She has cerebral palsy, and it still short of what she needs for a new car, after which the state will hook up and pay for the hand controls. If you would like to donate to this cause, click here. Afterwards, click on back-arrow to return to blog article.
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I AWOKE TO A PIECE ON NPR RADIO ABOUT A SERIES OF EARTHQUAKES IN EDMOND YESTERDAY. Edmond is an outer suburb of Oklahoma City. The largest quake was magnitude 4.2, and the radio quickly explained there was no damage.

My earthquake app said, “A noticeable shaking of indoor objects.” This of course is unsettling, because it always makes you wonder if the big one is coming.

In 2011, Edmond was rated #1 on CNBC’s “10 Perfect Suburbs” list. Maybe not any more!

A big one did come on 3 September 2016, centered on Pawnee, Oklahoma, north of Oklahoma City. Magnitude 5.8, and the largest ever earthquake in Oklahoma. I wrote a blog about this.

Magnitude 5 quakes do cause damage to poorly-constructed buildings. The following chart shows the damaging effects of different magnitudes.

THE STATS ON THE EDMOND EARTHQUAKES:
The spreadsheet below reveals 4 earthquakes within a period of 20 hours…. On the edge of a large city which adds to the unease. Looking closely we find three quakes initiated at a depth of 3-4 miles (16,000 to 21,000 ft). These quakes originated in the deep granite Basement. They were all close to the same GPS coords also. If it was the same fault, it shuddered and slipped three times within 20 hours….. which is a bit scary.

The remaining earthquake initiated at a much shallower depth of 1.4 miles = 7,400 ft, and this may be a separate fault, probably lying above the Basement.

EARTHQUAKES DECLINING IN OKLAHOMA
Definitely yes! The graph below shows this, and if projected out says only 274 quakes by end of 2017. This can be attributed to regulatory cutbacks of wastewater injected into disposal wells by the oil and gas industry.

Wastewater is mostly produced water, meaning water that is produced along with oil or gas. Immense volumes of produced water have been injected into the deep Arbuckle limestone formation over the years since 2009 when the revolution of shale-oil took off in Oklahoma. That’s when the quakes started….in 2009.

Because the Arbuckle lies right on top of the Basement rocks, which contain big faults. And big faults mean significant earthquakes if the injected water gets into the faults. Click here for a previous blog with more info about this.

BUT WAIT……the regulatory disposal well cutbacks (40% cutbacks) were issued in February 2016. And here we are 18 months later, with significant earthquakes still occurring in Oklahoma. Why? Unfortunately, the immense volumes of wastewater that have been injected into the Arbuckle limestone are still there, slowly spreading sideways, and the pressure of the water is only slowly dissipating.

Slowly is the key word, implying earthquakes can keep coming for months and years after injection rates are reduced in disposal wells. Yet Oklahomans are optimistic that big earthquakes of magnitude 5 or more have stopped coming: the chance is less than 12%, see image above.

OTHER POCKETS OF INJECTION-INDUCED EARTHQUAKES DO OCCUR OVER THE USA. One pocket is in the Barnett shale outside of Fort Worth, Texas. Another is in the Delaware basin in southeast New Mexico. And another is in southern Kansas, just across the border from Oklahoma.

But the deepest pocket, and the largest pocket by far, lies in Oklahoma.

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POST-SCRIPT: I’m writing a memoir called Rise of the Unconventionals: A memoir from cosmic rays to fracking and earthquakes.

The word Unconventionals refers to unconventional sources of oil and gas. For example, shale gas-and-oil is an unconventional resource that began in 2003. Coalbed methane is another one, and this took off in the early 1980s. I’ve been lucky to have worked in both areas during my career. And yes, the book will include a section on earthquakes induced by the oil and gas industry.
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The Gray Nomad ….. Think well.

On 29 December 2015, a magnitude 4.3 earthquake struck in northeastern Oklahoma County near the town of Edmond. The quake caused structural damage to at least one home and caused power outages to over four thousand residents. This was followed by a 4.2 magnitude earthquake on the morning of 1 January 2016, again in northeastern Oklahoma County in a nearby area. [Wikipedia: 2009-17 Oklahoma earthquake swarms].