Repost from the San Antonio Express-News
Quake experts think fracking maps may predict future temblors
Experts creating models to gauge future activity
By Sean Cockerham, Tribune News Service Washington Bureau, April 23, 2015 10:02pm
WASHINGTON — As earthquakes triggered by oil and gas operations shake the heartland, the federal government is scrambling to predict how strong the quakes will get and where they’ll strike.
The U.S. Geological Survey released maps Thursday that show 17 areas in eight states with increased rates of manmade earthquakes, including places such as North Texas, southern Kansas and Oklahoma where earthquakes were rare before fracking sparked a U.S. drilling boom in recent years.
Seismologists are using the maps in an attempt to create models that can predict the future of such quakes.
“These earthquakes are occurring at a higher rate than ever before and pose a much greater risk to people living nearby,” said Mark Petersen, chief of the USGS national seismic hazard modeling project.
Studies show the earthquakes primarily are caused by the injection of drilling wastewater from oil and gas operations into disposal wells, said Bill Ellsworth, a seismologist with the USGS.
The fact there have been many small earthquakes “raises the likelihood of larger earthquakes,” Ellsworth said. While most of the quakes have been modest, a 5.7-magnitude earthquake near Prague, Oklahoma, in 2011 destroyed 14 homes and was felt as far away as Milwaukee.
The USGS is working on a model, to be released at the end of the year, that can predict the hazards a year in advance.
People who live in areas with manmade quakes can use the forecasting information to upgrade structures to be safer and in order to learn what they should do in case of an earthquake, he said.
“Many of these earthquakes are now occurring in areas where people have not been familiar with earthquakes in the past,” Ellsworth said. “So there’s just a lot of basic education that is worth doing.”
The USGS maps show the earthquakes are mostly in Oklahoma, Texas and Kansas, but also Colorado, Ohio, Arkansas, Alabama and New Mexico.
“What we’ve seen is very, very large volumes of wastewater being injected over many different areas in the midcontinent, Oklahoma principally but also Kansas, Texas and other states,” Ellsworth said.
Fracking produces large amounts of wastewater, which oil and gas companies often pump deep underground as an economical way to dispose of it without contaminating fresh water. That raises the pressure underground and can effectively lubricate fault lines, weakening them and causing earthquakes.
While there was some initial skepticism, it’s become increasingly accepted that oil and gas activities are behind the surge in American earthquakes since 2008. Southern Methodist University researchers said in a research paper this week that these activities were the most likely cause of a rash of earthquakes that hit an area northwest of Fort Worth, Texas, from November 2013 to January 2014.
Oklahoma was rocked with nearly 600 earthquakes big enough for people to easily feel last year.
The Kansas Corporation Commission, a state regulatory agency, has responded to the earthquakes there with new rules that limit how much saltwater drilling waste can be injected underground. Ellsworth said seismic researchers were watching Kansas closely to see whether the new rules reduced the quakes.