By MICHAEL WINESMARCH 7, 2016
Facing a six-year barrage of increasingly large earthquakes, Oklahoma regulators are effectively ordering the state’s powerful oil-and-gas industry to substantially cut back the underground disposal of industry wastes that have caused the tremors across the state.
On Monday, the state Corporation Commission asked well operators in a Connecticut-size patch of central Oklahoma to reduce by 40 percent the amount of oil and gas wastes they are injecting deep into the earth. The directive covers 411 injection wells in a rough circle that includes Oklahoma City and points northeast.
It follows a February request that imposed a 40 percent cutback on injection wells in a similar-size region of northwest Oklahoma.
The actions significantly increase the effort to rein in the quakes, which the commission has long tried to reduce one well or a handful of wells at a time.
But they are an equally notable challenge to the industry, which will most likely be able to make the cutbacks only by reducing oil and gas production. The liquid wastes are a byproduct of pumping oil and gas, and the more that is drawn from the ground, the more wastes must be disposed of.
The directives were phrased as requests, because the Corporation Commission’s legal authority to order cutbacks over such broad areas is unclear. The commission has come close to legal battles over the issue twice this year, and a third challenge would not be a surprise. The commission has pledged to take to court any operator that refuses to carry out the reductions.
The Oklahoma Oil and Gas Association, the industry’s main trade group, did not return calls seeking comment. Most of the industry has cooperated with the commission’s earthquake reduction efforts in the past. But a handful have complied only under pressure.
The new orders come after three of the largest quakes in the state’s history, 4.7, 4.8 and 5.1-magnitude shocks that rocked a major oil field this year.
In 2010, when the tremors began, Oklahoma recorded three earthquakes at or above a magnitude of 3. Last year, it had 907. So far in 2016, it has had nearly 160.
Although critics contend that earthquakes have caused millions of dollars of damage, Oklahoma’s political leaders have long been reluctant to impose restrictions on an industry that dominates the state’s economy. Until last spring, Gov. Mary Fallin, a Republican, maintained that the cause of the tremors was unclear, and the state Legislature refused to consider legislation addressing the issue.
Ms. Fallin abandoned her position as the number of quakes rapidly increased. But the political leadership was not jolted into action until January, after a series of small earthquakes damaged homes and interrupted power in Edmond, an Oklahoma City suburb home to many in the state’s political and financial elite.
Seismologists have long warned that the rise in the number of earthquakes in Oklahoma could presage a temblor that could cause extensive damage.
“You really can’t rule out the possibility of a larger earthquake,” Justin L. Rubenstein, the deputy chief of a program on man-made earthquakes at the United States Geological Survey, said on Monday.
Reducing or stopping waste disposal often leads to a reduction in tremors, he said, but because Oklahoma has so many injection wells, “the problem is very complicated.”
The 40 percent cutbacks are based on the amount of waste injected into the wells in 2014, a peak year. Matt Skinner, a spokesman for the state Corporation Commission, said the latest directive was a proactive measure, based on a new and more detailed analysis of the quakes.
The directives come at a difficult time for industry companies, which Mr. Skinner said were generally pumping oil and gas at high rates to eke out a profit during a collapse in oil prices. Well operators can decide how to meet the 40 percent reduction target, he said, but “it is certainly possible that operators will decide to cut production.”
Some operators dispose of waste by trucking it elsewhere, but that is probably unprofitable when oil prices are so low.
A week after the last of the Edmond quakes, Governor Fallin allotted $1.4 million in state funds to the state geological survey and to the Corporation Commission, both of which had been chronically short of money. Among other improvements, the money has allowed the state to beef up its earthquake monitoring network, hire a geophysicist and other staff members, and better monitor quakes.
The Legislature is considering a bill introduced by an Edmond legislator and others that would allow the state insurance commissioner to create an earthquake reinsurance program. Residents of quake-prone areas have complained for years that private insurance was either impossible to get or that it included such high deductibles for damage that it was not worth buying.
Some critics incorrectly blame the earthquakes on hydrofracturing, or fracking, which frees hard-to-reach deposits by pumping liquids into the surrounding rock. Still, the rise in quakes tracks the increase in oil and gas wastes produced since a wave of fracking wells began operating in the middle of the last decade.
A version of this article appears in print on March 8, 2016, on page A12 of the New York edition with the headline: Oklahoma Acts on Oil and Gas Wells . Order Reprints Today's PaperSubscribehttp://www.nytimes.com/2016/03/08/us/oklahoma-earthquakes-oil-gas-wells.html?_r=0