Could Fracking Earthquakes Shake Pennsylvania?

Adapted from the National Energy Tech­nol­ogy Lab­o­ra­tory / Envi­ron­men­tal Pro­tec­tion Agency

Dia­gram of a deep well injec­tion site.

The New Year’s Eve earth­quake that shook Youngstown, Ohio mea­sured 4.0 on the Richter scale. The tem­blor was the largest of a series of quakes that had been rock­ing the area around Youngstown for sev­eral months and are blamed on a deep injec­tion well. No frack­ing hap­pens at deep injec­tion wells. But frack­ing waste­water is sent down those wells at high pres­sure as a method of disposal.

Researchers at Colum­bia University’s Lamont-Doherty Earth Obser­va­tory have stud­ied the earth­quakes in Ohio and iden­ti­fied the deep well they think caused the quake. The Youngstown well went into a sand­stone for­ma­tion, and then 300 feet fur­ther into more solid rock. John Arm­bruster, a seis­mol­o­gist with Lamont-Doherty, says the sand­stone in that area is not very porous.

“The sand­stone doesn’t want to accept this waste very eas­ily,” says Arm­bruster. “So you have to use a lot of pres­sure to force the waste into the sandstone.”

When that pres­sur­ized fluid came in con­tact with a fault, the earth started to shake. Arm­bruster says it’s unlikely that the sand­stone itself would have trig­gered a quake. But he says the Youngstown well was sunk deeper, into harder rock lay­ers, where earth­quakes were wait­ing to happen.

“The energy needs to be there,” says Armbruster.

In other words, it’s not just pump­ing large amounts of fluid down a hole into the earth. That fluid has to awaken a sleep­ing fault. Arm­bruster says it’s hard to know where those faults lie.

“You can say an earth­quake is more likely or less likely,” he says. But you can’t say an earth­quake is going to hap­pen or not going to hap­pen. There isn’t earth­quake prediction.”

But there are ways that hydrol­o­gists and geol­o­gists can assess risk fac­tors. Arm­bruster says things to look at are depth — does the well go beyond the sed­i­ment level and into the more solid base­ment lev­els? Are there lay­ers of sed­i­ment between the bot­tom of a well and the base­ment level that could absorb the extra pres­sure? The state of Ohio is updat­ing their rules about deep injec­tion wells after the Youngstown quakes.

Pennsylvania’s wells, how­ever, are reg­u­lated by the Envi­ron­men­tal Pro­tec­tion Agency. Cur­rently there are eight per­mit­ted injec­tion wells in Penn­syl­va­nia. Injec­tion wells are also called brine dis­posal wells, or class II under­ground injec­tion wells. They can take any fluid related to oil and gas drilling. Two newly per­mit­ted wells in War­ren County have not begun tak­ing frack water yet, and are under appeal. EPA offi­cials say they are look­ing at one new pro­posal. The EPA took over the task of per­mits, inspec­tions and enforce­ment from state reg­u­la­tors in 1985. The map below shows where the wells are located. A click on the blue icon dis­plays data on each brine water injec­tion well.

Click blue icon to dis­play pres­sure and vol­ume data on each brine water injec­tion well.

Unlike the Ohio wells, none of the Penn­syl­va­nia wells reach into the base­ment level for­ma­tion. Scott Platt is an EPA hydrol­o­gist and an expert in under­ground injec­tion con­trol. Platt says the state’s injec­tion wells are for­mer gas and oil pro­duc­ing wells.

“We do not allow the well to oper­ate at a pres­sure that would frac­ture a zone they go into,” says Platt.

Platt says the wells are in well known and well doc­u­mented for­ma­tions, so he says he feels com­fort­able with the permits.

Penn­syl­va­nia does have a his­tory of earth­quakes, but they’ve never been cat­a­strophic. The U.S. Geo­log­i­cal Survey’s Seis­mic Haz­ard Map for Penn­syl­va­nia shows a rel­a­tive low prob­a­bil­ity that the state would expe­ri­ence an earth­quake in the next 50 years. But it’s not much dif­fer­ent than Ohio’s map.

Seis­mol­o­gist John Arm­bruster says it’s not just injec­tion wells that can cre­ate earth­quakes. Pro­duc­tion work at quar­ries and oil fields can also shake loose unknown faults. He says a 1994 earth­quake in Read­ing, Pa., mea­sured more than a mag­ni­tude 4 on the Richter scale and cen­tered right below a quarry.

But can frack­ing itself cause earth­quakes? Arm­bruster doesn’t think so.

“Frack­ing wells tend to be shal­low and it takes a day or two [to com­plete],” says Arm­bruster. That’s not enough pres­sure into these faults in the base­ment to make an earthquake.”

But once a quake does hap­pen, Arm­bruster says the dam­age is done. The Ohio well injec­tion com­pany D & L Energy Group, has been ordered to pour cement into the bot­tom of the offend­ing well.

“They pumped into that well for at least a year,” says Arm­bruster. “That’s not going away overnight. That effect will spread out for at least sev­eral months.”

In fact, the earth­quakes that struck Youngstown, Ohio are not that far from a deep injec­tion well in Beaver County. But the EPA says the Beaver County well does not extend beyond the sand­stone layer. Three of Pennsylvania’s deep injec­tion wells are com­mer­cial, which means they can take water from any energy com­pany. The oth­ers are per­mit­ted only to dis­pose of their own frack water. Range Resources has an injec­tion well in Erie County, which is per­mit­ted to take the most frack water in the state at 45,000 bar­rels per month. Some take as low as 4200 bar­rels per month, but most of them can take about 30,000 bar­rels a month. EXCO Resources oper­ates two in Clearfield County. Other oper­a­tors include Colum­bia Gas, in Beaver County; and Cot­ton­wood and CNX Gas in Som­er­set. When it comes to pres­sure, the wells are per­mit­ted to take between 1300 to about 3200 pounds per square inch. If approved, the two newest wells will be oper­ated by Bear Lake Prop­er­ties in War­ren County. All eight wells are in the west­ern part of the state.

The oil and gas indus­try uses injec­tion wells to dis­pose of waste water, which has a high salt con­tent, as well as chem­i­cals and heavy met­als. Much of the frack water pro­duced in Penn­syl­va­nia gets trucked to Ohio, which has more dis­posal wells. Water can also be treated at pri­vate treat­ment facil­i­ties. The process cleans most of the water, but at least some smaller amount of fluid still needs to be injected back into the ground.

Ohio is not the only state expe­ri­enc­ing gas related earth­quakes. Arkansas reg­u­la­tors banned the use of deep injec­tion wells to dis­pose of waste­water after they found the activ­ity caused a rise in small earth­quakes last win­ter. The Arkansas Geo­log­i­cal Sur­vey told the AP last July that seis­mic activ­ity decreased dra­mat­i­cally once the wells were shut down. The Arkansas Oil and Gas Com­mis­sion has not banned frack­ing, only the use of wells to dis­pose of wastewater.

More than 40 years ago, a study con­ducted by the U.S. Geo­log­i­cal Sur­vey attrib­uted a 5.3 mag­ni­tude earth­quake in 1967 to a large injec­tion well at the Rocky Moun­tain Arse­nal in Den­ver, Col­orado. Sev­eral smaller earth­quakes fol­lowed the larger one.

A more recent study by South­ern Methodist Uni­ver­sity and the Uni­ver­sity of Texas also linked a rash of small earth­quakes in the Dallas-Fort Worth area in 2008 and 2009 to deep injec­tion wells used to dis­pose of nat­ural gas waste­water. But as the study’s authors pointed out, many sim­i­lar wells oper­ated in areas where no seis­mic activ­ity occurred.

The Army Corps of Engi­neers has expressed con­cern about drilling for nat­ural gas near dams and has a national team study­ing the poten­tial impact. The Corps has requested a 3000 foot buffer around dams because it wor­ries that frack­ing near fault lines could cause earth­quakes or shifts in sed­i­ment that would weaken dam struc­tures. CBS 11 News in Dal­las reports that the Corp’s Fort Worth dis­trict wrote a let­ter in Sep­tem­ber to town offi­cials in Grand Prairie, Texas warn­ing them that a nearby Chesa­peake Energy gas well site could poten­tially cause a “cat­a­strophic dam failure.”