(UPDATE 3*) AP Excloo? : Fracking quakes don’t feel as strong..umm, as big of a deal, hmmm, oomphy! Magnitudinous?

A federal scientist, poring through records from a US Geological Survey standard on line questionnaire asking how big an earthquake feels, has found something odd. Manmade quakes, which almost always refers those caused by injecting fluids into the ground as in fracking, tend to feel gentler and cause less damage or other drama than natural ones of the same measured magnitude,  or energy release. It is not a huge effect unless one’s brain is comfortable thinking on an exponential scale and probably won’t change public worry about such quakes. But it is a curiosity.

   We learn this first thanks to some diligent beat work by a seasoned science writer:

• AP – Seth Borenstein: Less Shake From Artificial Quakes, Fed Study Says ;

  Borenstein told the tracker by email that he regularly checks the Bulletin of the Seismological Society of America. He said he spotted a study  by a prominent seismologist at the USGS’s Pasadena office on Monday. There was no new release, he said. So chalk one up for reporting the old-fashioned way of not just reading what the in-box happens to have in it from press agents – or worse, rewriting other reporters’ news stories.

*UPDATE1! : Another outlet has the news and appears to have filed later, but not by much,  than Borenstein did.

• Wall Street Journal – Tamara Audi:Earthquake Study Shows Natural Quakes Outshake Man-Made Tremors ;

*UPDATE2! : Seth has to be believed when he says that he did not get it,  but others did get this press release last week from Nan Broadbent at the SSA:

Sent: Wednesday, August 13, 2014 7:15 AM
Subject: Embargoed: Shaking from induced v. tectonic quakes

Embargoed: Monday, August 18, 2014, 5 p.m., Eastern-U.S.

Induced quakes rattle less than tectonic quakes, except near epicenter

Induced earthquakes generate significantly lower shaking than tectonic earthquakes with comparable magnitudes, except within 10 km of the epicenter, according to a study to be published online August 19 in the Bulletin of the Seismological Society of America (BSSA). Within 10 km of the epicenter, the reduced intensity of shaking is likely offset by the increased intensity of shaking due to the shallow source depths of injection-induced earthquakes. 

Using data from the USGS “Did You Feel It?” system, Seismologist Susan Hough explored the shaking intensities of 11 earthquakes in the central and eastern United States (CEUS) considered likely caused by fluid injection. 

“Although moderate injection-induced earthquakes in the CEUS will be widely felt due to low regional attenuation,” writes Hough, “the damage from earthquakes induced by injection will be more concentrated in proximity to the event epicenters than shaking from tectonic earthquakes.”  

           The BSSA paper, “Shaking from Injection-Induced Earthquakes in the Central and Eastern United States,” is attached and is embargoed for Monday, August 18, 2014, at 5 p.m. Eastern-U.S.

*UPDATE 3 : Another major outlet had the story almost same moment as the AP:

• Nature News – Alexandra Witze: Man-made quakes shake the ground less than natural ones ; Enough quotes from the paper’s author to get a decent sense of her motivations, and includes quotes from another seismologist whose studies had hinted at the same conclusions.

Original post continues below –

 

   Interesting, the study revealed no notable difference in how people experience a quake if they are right on top of it – within six miles or so. But farther away fewer people, for quakes of a given magnitude, tend to report less sensation and fewer physical effects  such as pictures knocked askew, fallen chimneys, cracked walls, and trouble walking while the earth trembled.

   The most challenging aspect of this news is how to describe the difference in perception in the aggregate between human-caused and natural tectonic or volcanic earthquakes. Borenstein writes that in general the fracking-type quakes feel about 16 times ‘weaker’ than the regular ones. Wow, you say. But earthquake magnitude scales are exponential, with an approximate 30-fold difference in energy release (and ten-fold increase in ground-shaking) for every full unit of difference. For instance,  a 4.8 magnitude frack-quake on average feels like a 4.0 magnitude one that happened without human intervention. Most people won’t feel such a big wow from that.

   Seems to me, without having a better alternative to offer, that equating magnitude to a quake’s strength or power or size or any other common word is imprecise. Even energetic falls short. If something accelerates you to 30 mph in a quarter of a second, that’ll hurt. If it takes ten seconds it is just a pleasant whoosh. The energy released is the same either way. Is it stronger? I am unsure. If a big guy can lift 300 pounds in one heave but then is flat tuckered out, he is stronger than a weak guy who can only raise 50 pounds. But if the little fellow can do it ten straight times he’ll expend more energy. Plus, one feels ground shaking, not some vague measure of total energy released as miles of fault give way for a period of time.

   More important to the story’s importance as science is that the gentler release of energy in a fracking quake is not yet understood. Borenstein reports it may have to do with the fluid injected into deep strata providing lubrication in the fracture zone so that the movement is smoother and less likely to jar and break things.

   Good reporting. We all at ksjtracker have benefited often from Seth B’s tips and comments, and sharp news digging and writing, over the years.     

AP and Borenstein didn’t get credit everywhere – as in this Albuquerque Journal story attributed to staff, but the wire service appears to done the only reporting. And a Tulsa radio station runs the news in four short paragraphs, and puts a byline on it. Looks like AP’s the source.