Geophysicists link fracking boom to increase in earthquakes

 

By SEAN COCKERHAM

McClatchy Washington Bureau May 1, 2014

WASHINGTON — The swarm of earthquakes went on for months in North Central Texas, rattling homes, with reports of broken water pipes and cracked walls and locals blaming the shudders on the hydraulic fracturing boom that’s led to skyrocketing oil and gas production around the nation.

Darlia Hobbs, who lives on Eagle Mountain Lake, about a dozen miles from Fort Worth, said that more than 30 quakes hit from November to January.

“We have had way too many earthquakes out here because of the fracking and disposal wells,” she said in an interview.

While the dispute over the cause remains, leading geophysicists are now saying Hobbs and other residents might be right to point the finger at oil and gas activities.

“It is certainly possible, and in large part that is based on what else we’ve seen in the Fort Worth basin in terms of the rise of earthquakes since 2008,” William Ellsworth, a U.S. Geological Survey seismologist, said in an interview Thursday.

Ellsworth said the Dallas-Fort Worth region previously had just a single known earthquake, in 1950.

Since 2008, he said, more than 70 have been big enough to feel. Those include earthquakes at the Dallas-Fort Worth airport that scientists linked to a nearby injection well.

Ellsworth briefed his colleagues on his findings Thursday at the Seismological Society of America’s annual meeting in Anchorage.

Researchers also are investigating links between quakes in Kansas, Oklahoma, Ohio and elsewhere to oil and gas activities. USGS seismologist Art McGarr said it was clear that deep disposal of drilling waste was responsible for at least some of the quakes in the heartland.

“It is only a tiny fraction of the disposal wells that cause earthquakes large enough to be felt, and occasionally cause damage,” McGarr said. “But there are so many wells distributed throughout much of the U.S., they still add significantly to the total seismic hazard.”

While causes are under debate, it’s established that earthquakes have spiked along with America’s fracking boom. The USGS reports that an average of more than 100 earthquakes a year with a magnitude of 3.0 or more hit the central and eastern U.S. in the past four years.

That compares with an average rate of only 20 observed quakes a year in the decades from 1970 to 2000.

Regulators in Ohio found what they said was a probable connection between small quakes in the northeast corner of that state and the process of hydraulic fracturing, or fracking, in which high-pressure water and chemicals are pumped underground to break up shale rock and release the oil and natural gas inside.

But the USGS considers it very rare for fracking itself to cause earthquakes. Far more often the issue is quakes caused by the disposal of the wastewater into wells.

Fracking produces large amounts of wastewater, which companies often pump deep underground as an economical way to dispose of it. Injection raises the underground pressure and can effectively lubricate fault lines, weakening them and causing quakes, according to the USGS.

USGS seismologist Ellsworth said that near Fort Worth, two disposal wells were close enough to the earthquakes to be responsible. He said more research was needed.

Ellsworth and his colleagues, including seismologists from Southern Methodist University, in their presentation Thursday ruled out the idea that the falling level of a nearby lake might be contributing. But he said they couldn’t entirely reject the possibility of other natural causes — despite earthquakes being virtually unheard of in the region before 2008, which matches the start of the fracking boom.

Hobbs, of Eagle Mountain Lake, Texas, said she’d lived in the area since 1967 and never even considered the possibility of earthquakes.

“It’s spooky,” she said.

Earthquakes shake Texas town on Thanksgiving, and fracking might be to blame

By John Upton, Grist

Residents of a rural northern Texas area were awoken early on Thanksgiving by not one but two earthquakes. Such quakes have become alarmingly normal during the past month, and fracking practices could be to blame.

From CBS Dallas / Fort Worth:

North Texas has been feeling a string of earthquakes — more than a dozen — over the past few weeks. Most have been centered around Azle, with the most recent [previous] one being on Tuesday morning. All of those quakes have registered between 2.0 and 3.6 in magnitude. Those who live in the small town have grown concerned.

Azle leaders have called on state officials to have geologists investigate the cause of these quakes. “The citizens are concerned,” said Azle Assistant City Manager Lawrence Bryant at a city council meeting. “They should be.”

“If it’s a man-made cause, it would be nice to know,” Bryant added.

 

By “man-made,” Bryant means fracking-industry-made. Frackers pump their polluted wastewater deep into the ground, a practice well known as a cause of temblors. A wastewater injection well was shut down near Youngstown, Ohio, in late 2011 after it triggered more than 100 earthquakes of growing intensity in just a year.

University of Texas earthquake researcher Cliff Frolich says the recent Texas flurry could be the result of wastewater injection. From KHOU:

“I’d say it certainly looks very possible that the earthquakes are related to injection wells,” [Frolich] said in an interview from Austin.

Frolich notes, however, that thousands of such wells have operated in Texas for decades, with no quakes anywhere near them. He adds that there are probably a thousand unknown faults beneath Texas.

Azle mayor Alan Brundrett says it’s important to determine whether this latest series of quakes are man-made.

“What could it cause, down the road?” he asked. “What if a 5.0 happens and people’s houses start falling in on them?”

Brundrett has installed an earthquake alert app on his smartphone. It shows a dozen minor quakes near his town since November 5.

The growing problem of earthquakes in America is not just limited to Ohio and Texas. The following U.S. Geological Survey graph shows how the number of earthquakes with a magnitude of at least three has spiked as fracking has become widespread. “USGS scientists have found that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells,” the agency notes.

Click to embiggen.
USGS
 

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

Some Volcanoes ‘Scream’ at Ever-Higher Pitches until They Blow their Tops

It is not unusual for swarms of small earthquakes to precede a volcanic eruption. They can reach a point of such rapid succession that they create a signal called harmonic tremor that resembles sound made by various types of musical instruments, though at frequencies much lower than humans can hear.

By Vince Stricherz | University of Washington 07/15/2013

 

Redoubt Volcano’s active lava dome as it appeared on May 8, 2009. The volcano is in the Aleutian Range about 110 miles south-southwest of Anchorage, Alaska.Image-Chris Waythomas, Alaska Volcano Observatory

Redoubt Volcano’s active lava dome as it appeared on May 8, 2009. The volcano is in the Aleutian Range about 110 miles south-southwest of Anchorage, Alaska.Image-Chris Waythomas, Alaska Volcano Observatory

A new analysis of an eruption sequence at Alaska’s Redoubt Volcano in March 2009 shows that the harmonic tremor glided to substantially higher frequencies and then stopped abruptly just before six of the eruptions, five of them coming in succession.

“The frequency of this tremor is unusually high for a volcano, and it’s not easily explained by many of the accepted theories,” said Alicia Hotovec-Ellis, a University of Washington doctoral student in Earth and space sciences.

Documenting the activity gives clues to a volcano’s pressurization right before an explosion. That could help refine models and allow scientists to better understand what happens during eruptive cycles in volcanoes like Redoubt, she said.

The source of the earthquakes and harmonic tremor isn’t known precisely. Some volcanoes emit sound when magma – a mixture of molten rock, suspended solids and gas bubbles – resonates as it pushes up through thin cracks in the Earth’s crust.

But Hotovec-Ellis believes in this case the earthquakes and harmonic tremor happen as magma is forced through a narrow conduit under great pressure into the heart of the mountain. The thick magma sticks to the rock surface inside the conduit until the pressure is enough to move it higher, where it sticks until the pressure moves it again.

Each of these sudden movements results in a small earthquake, ranging in magnitude from about 0.5 to 1.5, she said. As the pressure builds, the quakes get smaller and happen in such rapid succession that they blend into a continuous harmonic tremor.

“Because there’s less time between each earthquake, there’s not enough time to build up enough pressure for a bigger one,” Hotovec-Ellis said. “After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes.”

She is the lead author of a forthcoming paper in the Journal of Volcanology and Geothermal Research that describes the research. Co-authors are John Vidale of the UW and Stephanie Prejean and Joan Gomberg of the U.S. Geological Survey.

Hotovec-Ellis is a co-author of a second paper, published online July 14 in Nature Geoscience, that introduces a new “frictional faulting” model as a tool to evaluate the tremor mechanism observed at Redoubt in 2009. The lead author of that paper is Ksenia Dmitrieva of Stanford University, and other co-authors are Prejean and Eric Dunham of Stanford.

The pause in the harmonic tremor frequency increase just before the volcanic explosion is the main focus of the Nature Geoscience paper. “We think the pause is when even the earthquakes can’t keep up anymore and the two sides of the fault slide smoothly against each other,” Hotovec-Ellis said.

She documented the rising tremor frequency, starting at about 1 hertz (or cycle per second) and gliding upward to about 30 hertz. In humans, the audible frequency range starts at about 20 hertz, but a person lying on the ground directly above the magma conduit might be able to hear the harmonic tremor when it reaches its highest point (it is not an activity she would advise, since the tremor is closely followed by an explosion).

Scientists at the USGS Alaska Volcano Observatory have dubbed the highest-frequency harmonic tremor at Redoubt Volcano “the screams” because they reach such high pitch compared with a 1-to-5 hertz starting point. Hotovec-Ellis created two recordings of the seismic activity. A 10-second recording covers about 10 minutes of seismic sound and harmonic tremor, sped up 60 times. Aone-minute recording condenses about an hour of activity that includes more than 1,600 small earthquakes that preceded the first explosion with harmonic tremor.

Upward-gliding tremor immediately before a volcanic explosion also has been documented at the Arenal Volcano in Costa Rica and Soufrière Hills volcano on the Caribbean island of Montserrat.

“Redoubt is unique in that it is much clearer that that is what’s going on,” Hotovec-Ellis said. “I think the next step is understanding why the stresses are so high.”

The work was funded in part by the USGS and the National Science Foundation.

Source: University of Washington

Confirmed: Fracking triggers quakes and seismic chaos

quake_630_2By Kate Sheppard, Brett Brownell, and Jaeah Lee, Source: Grist

Major earthquakes thousands of miles away can trigger reflex quakes in areas where fluids have been injected into the ground from fracking and other industrial operations, according to a study published in the journal Science on Thursday.

Previous studies, covered in a recent Mother Jones feature from Michael Behar, have shown that injecting fluids into the ground can increase the seismicity of a region. This latest study shows that earthquakes can tip off smaller quakes in far-away areas where fluid has been pumped underground.

The scientists looked at three big quakes: the Tohuku-oki earthquake in Japan in 2011 (magnitude 9), the Maule in Chile in 2010 (an 8.8 magnitude), and the Sumatra in Indonesia in 2012 (an 8.6). They found that, as much as 20 months later, those major quakes triggered smaller ones in places in the Midwestern U.S. where fluids have been pumped underground for energy extraction.

“[The fluids] kind of act as a pressurized cushion,” lead author Nicholas van der Elst of the Lamont-Doherty Earth Observatory at Columbia University explained to Mother Jones. “They make it easier for the fault to slide.”

The finding is not entirely surprising, said van der Elst. Scientists have known for a long time that areas with naturally high subsurface fluid pressures — places like Yellowstone, for example — can see an uptick in seismic activity after a major earthquake even very far away. But this is the first time they’ve found a link between remote quakes and seismic activity in places where human activity has increased the fluid pressure via underground injections.

“It happens in places where fluid pressures are naturally high, so we’re not so surprised it happens in places where fluid pressures are artificially high,” he said.

The study looked specifically at Prague, Okla., which features prominently in Behar’s piece. The study links the increased tremors in Prague, which has a number of injection wells nearby, to Chile’s Feb. 27, 2010, quake. The study also found that big quakes in Japan and Indonesia triggered quakes in areas of Western Texas and Southern Colorado with many injection wells. The study is “additional evidence that fluids really are driving the increase in earthquakes at these sites,” said van der Elst.

Drillers inject high-pressure fluids into a hydraulic fracturing well, making slight fissures in the shale that release natural gas. The wastewater that flows back up with the gas is then transported to disposal wells, where it is injected deep into porous rock. Scientists now believe that the pressure and lubrication of that wastewater can cause faults to slip and unleash an earthquake.
Leanne Kroll / Brett Brownell
Drillers inject high-pressure fluids into a hydraulic fracturing well, making slight fissures in the shale that release natural gas. The wastewater that flows back up with the gas is then transported to disposal wells, where it is injected deep into porous rock. Scientists now believe that the pressure and lubrication of that wastewater can cause faults to slip and unleash an earthquake.

This story was produced for Mother Jones as part of the Climate Desk collaboration.

Brett Brownell is the multimedia producer at Mother Jones.

Jaeah Lee is the associate interactive producer at Mother Jones.

Kate Sheppard was Grist’s political reporter until August 2009. She now covers energy and environmental politics for Mother Jones. Read her work and follow her on Twitter.