March 27, 2013 in Nation/World

Report: Oklahoma quake likely man-made

Associated Press
 

WASHINGTON – An unusual and widely felt 5.6-magnitude quake in Oklahoma in 2011 was probably caused when oil drilling waste was pushed deep underground, a team of university and federal scientists concluded.

That would make it the most powerful quake to be blamed on deep injections of wastewater, according to a study published Tuesday by the journal Geology. The waste was from traditional drilling, not from the hydraulic fracturing technique, or fracking.

Not everyone agrees, though, with the scientists’ conclusion: Oklahoma’s state seismologists say the quake was natural.

The Nov. 6 earthquake near Prague, Okla., injured two people, damaged 14 houses and was felt for hundreds of miles in 14 states, according to the U.S. Geological Survey. It was the largest quake in the central part of the country in decades, experts said.

The study by geophysicists at the University of Oklahoma, Columbia University and the USGS says that a day earlier there was a slightly smaller quake in an old oil well used to get rid of wastewater, right along a fault line. That smaller quake triggered the bigger one, and a third smaller aftershock.

The location of the tremors right at the spot where wastewater was stored, combined with an increased well pressure, makes a strong case that the injections resulted in the larger quake, they said.

In a statement, the Oklahoma Geological Survey said the interpretation that best fits the data is the quake “was the result of natural causes” but needs further study. The state officials cited new 3-D seismic data, a time lag between injection and the quakes, and the orientation of the faults to say it was natural not induced.

© Copyright 2013 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Get stories like this in a free daily email


Please keep it civil. Don't post comments that are obscene, defamatory, threatening, off-topic, an infringement of copyright or an invasion of privacy. Read our forum standards and community guidelines.

You must be logged in to post comments. Please log in here or click the comment box below for options.

comments powered by Disqus