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Comment by jandrewrogers | Hacker News Reader

Oklahoma is a seismically active region that has always had a lot of earthquakes in the magnitude 5 range. USGS even has dedicated seismic hazard maps for Oklahoma. This has been going on long before anyone was fracking in Oklahoma.

Most Americans are unaware that Oklahoma is an active seismic zone and articles like this prey on that ignorance by implying that these earthquakes arrived with fracking. There is a lot of fracking in places do not naturally have a lot of earthquakes but the fact that they always pick Oklahoma suggests that they are trying to construct a false correlation.

A lot of fracking occurs in California too but most people understand that earthquakes in California are going to happen whether you frack or not. Same with Oklahoma.

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I don't think anyone really disputes that there are an increasing number of earthquakes, both in Oklahoma and elsewhere.

http://www.usgs.gov/blogs/features/files/2013/07/2013-hockey...

Like cancer, once can show that something causes an increased rate of earthquakes (on top of an underlying base rate) even if no individual earthquake can be definitively attributed to that cause.

> A team of USGS scientists led by Bill Ellsworth analyzed changes in the rate of earthquake occurrence using large USGS databases of earthquakes recorded since 1970. The increase in seismicity has been found to coincide with the injection of wastewater in deep disposal wells in several locations, including Colorado, Texas, Arkansas, Oklahoma and Ohio. Much of this wastewater is a byproduct of oil and gas production and is routinely disposed of by injection into wells specifically designed and approved for this purpose.

> Hydraulic fracturing, commonly known as “fracking,” does not appear to be linked to the increased rate of magnitude 3 and larger earthquakes.

http://earthquake.usgs.gov/research/induced/

"Oklahoma is a seismically active region that has always had a lot of earthquakes in the magnitude 5 range."

I don't think the historical record supports this assertion, for any reasonable interpretation of "a lot". I found this table:

http://paleoseismicity.org/m5-6-earthquake-in-oklahoma/

showing only one earthquake of >= M5 in Oklahoma in the last 70 years (an M5.5 in 1952). That is, excluding the ramp-up since 2008 and in particular the Prague, OK M5.6 (2011).

This sparse historical record of M5 earthquakes is also supported by the linked graph from USGS (http://earthquake.usgs.gov/research/induced/) that shows about 20 events/year of M3 or larger in the entire central-eastern US (pre-2009 -- the rate increases after 2005-2009).

The simple version of the Gutenberg-Richter relation predicts 10x fewer earthquakes for each unit jump in M. So, very roughly, that would imply 0.2 earthquakes per year of M5 or above across the central-eastern US, a region much larger than Oklahoma. The actual rate observed in the 20th century appears significantly lower than this.

As the article states, up until 2008 Oklahoma averaged 1 earthquake per year of magnitude 3.0 or greater. In 2014 there were over 500.

http://earthquake.usgs.gov/earthquakes/states/oklahoma/image...

As someone who has lived in OK for 30+ years, this is absolutely false.

Here is a chart of the largest recorded earthquakes in Oklahoma. Only two have been greater than 5.0.

http://www.okgeosurvey1.gov/pages/earthquakes/information.ph...

Also note how many have occurred in the past 5 years.

One of the key differences between Oklahoma & California earthquakes is the relative depth of quakes of significant magnitude.

Quakes caused by tectonic plate interaction and those possibly caused by fluid injection may not be usefully comparable - but ask a seismologist, or at least a geologist, not a journalist, or a random internet commenter.

There's a nice interactive quake map at:

http://earthquake.usgs.gov/earthquakes/map

edit: Pasting a long (512+ chars) URL did not work well, but use the settings sprocket and the checkboxes for US Faults & Hazards.

BTW, the hot spot in the Missouri/Arkansas area is the "New Madrid" fault, locally pronounced with the stress on the first syllable: "Mad-rid" not "Mu-drid". It makes emergency preparedness folks nervous because it had a big quake in the early 1800s, very little since, and now has lot of brick construction - sigh.

Describing the New Madrid quake as "big" is a bit of an understatement. Closer to "The Day the Earth Stood Still" in terms of impact.

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