The state of Oklahoma is not known for earthquakes but for the first three months of 2014 Oklahoma had more earthquakes than California. Now the USGS has issued it’s first earthquake warning for a state east of the Rockies.
Mile for mile, there are almost as many earthquakes rattling Oklahoma as California this year. This major increase in seismic shaking led to a rare earthquake warning today (May 5) from the U.S. Geological Survey and the Oklahoma Geological Survey.
In a joint statement, the agencies said the risk of a damagingearthquake — one larger than magnitude 5.0 — has significantly increased in central Oklahoma.
Geologists don’t know when or where the state’s next big earthquake will strike, nor will they put a number on the increased risk. “We haven’t seen this before in Oklahoma, so we had some concerns about putting a specific number on the chances of it,” Robert Williams, a research geophysicist with the USGS Earthquake Hazards Program in Golden, Colorado, told Live Science. “But we know from other cases around the world that if you have an increasing number of small earthquakes, the chances of a larger one will go up.” [Watch 2500+ Oklahoma Earthquakes Since 2012 (Video)]
So why is this happening?
While scientists haven’t ruled out natural causes for the increase, many researchers suspect the deep injection wells used for the disposal of fracking wastewater could be causing the earthquake activity. Fracking, short for hydraulic fracturing, is a method of extracting oil and gas by cracking open underground rock.
Ongoing studies have found a link between Oklahoma’s high-volume wastewater injection wells and regions with an uptick in earthquakes.
According to the USGS, the number of quakes magnitude-3 and stronger jumped by 50 percent in the past eight months in Oklahoma. Some 183 earthquakes of magnitude 3 or greater struck between October 2013 and April 14, 2014. The state’s long-term average from 1978 to 2008 was only two earthquakes of magnitude 3.0 or larger per year.
One problem is that while the west coast has building codes that take into account the possibility of earthquakes Oklahoma does not. While a 5 earthquake in Oregon, Washington or California wouldn’t do much damage in Oklahoma it not only will but already has.
“Building owners and government officials should have a special concern for older, unreinforced brick structures, which are vulnerable to serious damage during sufficient shaking,” Bill Leith, a USGS senior science adviser for earthquakes and geologic hazards, said in the joint statement.
There has already been a 5,7 earthquake in Prague, Oklahoma that caused damage.
One of Oklahoma’s biggest man-made earthquakes, caused by fracking-linked wastewater injection, triggered an earthquake cascade that led to the damaging magnitude-5.7 Prague quake that struck on Nov. 6, 2011, a new study confirms.
The findings suggest that even small man-made earthquakes, such as those of just a magnitude 1 or magnitude 2, can trigger damaging quakes, said study co-author Elizabeth Cochran, a seismologist with the U.S. Geological Survey.
“Even if wastewater injection only directly affects a low-hazard fault, those smaller events could trigger an event on a larger fault nearby,” she told Live Science.