Oklahoma Gets Rare ‘Damaging Earthquake’ Alert

In a very rare joint statement, the U.S. Geological Survey and the Oklahoma Geological Survey issued a warning of a damaging earthquake of more that 5.0 magnitude for central Oklahoma.

Robert Williams, a research geophysicist with the USGS Earthquake Hazards Program in Golden, Colorado, told Live Science:

“We haven’t seen this before in Oklahoma, so we had some concerns about putting a specific number on the chances of it. 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.  That’s why earthquakes of magnitude 5 and larger are more frequent in states such as California and Alaska, where thousands of smaller temblors hit every year”

This is the first time the USGS has issued an earthquake warning for a state east of the Rockies, Williams said. Such seismic hazard assessments are more typically issued for Western states following large quakes, to warn residents of the risk of damaging aftershocks. (source)

For the first time the number of small earthquakes in Oklahoma was more than the number of tremblors in California during the first three months of 2014. It was this that prompted the alert.

Many of the buildings in central Oklahoma can, and do, withstand small earthquakes, but the fears are that anything over a magnitude 5.0 would cause widespread damage. Oklahoma’s last major earthquake was in November 2011, when a magnitude 5.6 earthquake centered near Prague, Oklahoma, destroyed 14 homes and injured at least two people.

Bill Leith, Senior Science Advisor for USGS said:

“Building owners and government officials should have a special concern for older, un-reinforced brick structures, which are vulnerable to serious damage during sufficient shaking,” (source)

Researchers believe that fracking may be the cause of the huge increase in earthquakes in the area. The deep injection wells used for the disposal of wastewater caused by the process puts huge pressure on existing faultlines, sometimes tens of miles away from the well itself.

The uptick in earthquakes of all sizes showed a staggering 50% rise in the first three months of the year. More alarmingly, 183 magnitude 3.0 and above earthquakes occurred during the seven month period from October 2013 and April 24th 2014.

The long term average of 3+ quakes was on average 2 per year between 1978 and 2008.