You may have heard: Oklahoma has had a rash of earthquake activity the past several weeks. We’re used to high winds, supercells, tornadoes and drought, but recent earthquakes have shaken the nerves of many Oklahomans.
In fact, according to the “Quakes” smart phone app, Oklahoma was the most geologically active state for a 48 hour run some weeks ago. We even had a tornado and an earthquake on the same day!
The locations of the initial quake and aftershocks were near Prague and Meeker, OK–although some of the activity has been felt statewide. Surely, discussions of plate tectonics, earthquakes and the correlation between the two ensued in classrooms and lecture halls across the state. Not very big news for our friends on the west coast or residents near boundaries of tectonic plates . . . but nonetheless, it’s served as a source of excitement for us Oakies.
So is it the end of the Mayan calendar or all the drilling that’s going on?
This begs the question: why is Oklahoma experiencing earthquake activity all of a sudden? Popular explanations I’ve heard include the approach of 2012 or all of the recent oil & gas drilling–in particular the practice of hydrofracking (hydraulic fracturing). My standard reply is that no matter where you are, rock strata and sediment miles below the surface are constantly under stress and strain. Eventually, earth material will yield to these forces along a boundary whose integrity has been weakened over time. Typically this occurs at the boundaries of tectonic plates, but scores of intraplate faults exist far within the boundaries of these plates, too. And Oklahoma is no exception (see some of the links provided at http://earthquake.usgs.gov/earthquakes/states/?region=Oklahoma for example). What we do at the surface or what the calendar date may be are most likely just coincidental.
My point: regardless of the proximity to the year 2012 and hydrofracking sites, Oklahoma has a history of earthquake activity. Associating a single cause separated from the geologic pedigree would be like saying one’s car broke down because it ran out of windshield washing fluid–most likely there is more to the story.
What I find interesting is that despite the seismic data, known earthquake history and locations of fault lines, geologists often have difficulty directly linking a specific seismic event to a single geologic fault. This further emphasizes my point above.
All that said, I am in full support of testing hypotheses. While I give the approach of the end of the Mayan calendar as a cause for geologic activity very little credence, one could test the plausibility of hydrofracking as a potential cause. Afterall, hydrofracking may occur at or near the depths of some of the recently recorded earthquakes in Oklahoma. Using www.usgs.gov (or for a more direct link to a recent publication, see http://www.ogs.ou.edu/earthquakes/Okseismicity11_6_2011.pdf), the earthquakes’ locations and depths could be plotted. Then, hydrofracking sites with corresponding depths could be compared. These data will be more difficult to collect. Just keep in mind that correlations do not necessarily mean cause and effect.