Interesting Vox article on natural and manmade earthquakes my fellow Vet and cohort in writing Mark Jamison sent me. This year for the first time ever the USGS is including a map of areas in the US which may be prone to human-induced earthquakes” in addition to areas which are prone to natural earthquakes.
“By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.,” said Mark Petersen, Chief of the USGS National Seismic Hazard Mapping Project. “This research also shows that much more of the nation faces a significant chance of having damaging earthquakes over the next year, whether natural or human-induced.”
From the highest to the lowest potential hazard the USGS has ranked these states: Oklahoma, Kansas, Texas, Colorado, New Mexico and Arkansas. Oklahoma and Texas have the largest populations exposed to induced earthquakes. Small areas of Ohio and Alabama have experienced induced earthquakes; but, this has dropped off with lesser activity. “Wastewater disposal is thought to be the primary reason for the recent increase in earthquakes in the CEUS. While most injection wells are not associated with earthquakes, some other wells have been implicated in published scientific studies, and many states are now regulating wastewater injection in order to limit earthquake hazards.”
Central US has experienced the greatest change in earthquake frequency going from 24 earthquakes per year (1973 to 2008) with an average magnitude of 3.0 to increased frequency year over year 318 per year with a high of 1010 in 2015. From 2009 to 2015, the rate steadily increased, averaging 318 per year and peaking in 2015 with 1,010 earthquakes. The latest data through mid-March shows 226 earthquakes. As fracking and the resulting waste water injection activities picks up in a region, the frequency of earthquakes increases. It is not believed Hydraulic fracking is to be the cause of the increased earthquakes. Testing the maps after one year will verify predictability of location and frequency of earthquakes.