Fracking is the pumping of huge amounts of water, sand, and dangerous chemicals into the ground to cause or increase fractures in the rock, which releases natural gas. There is a heated debate going on about the safety of this fracking. Gas companies claim it is a safe procedure. Many others disagree, claiming it poisons the earth around it and the water many communities depend on.
Now there are claims that this fracking is having another negative effect. That it is causing earthquakes in Texas (and Oklahoma) -- areas that have been earthquake-free for eons, but having been experiencing them since 2008 (when fracking became common in the area).
Is this true? Very likely. Now there is some scientific evidence that those earthquakes, some as large as a magnitude 4, are being caused by fracking. Here is part of an excellent article on this by Anna Kuchment in the Dallas Morning News:
Scientists presented new evidence this week suggesting that all five North Texas earthquake sequences, including those in Dallas, have been triggered by humans.
Until now, researchers have not commented on the cause of the Dallas-Irving quakes or the 4-magnitude quake that struck Venus, 30 miles south of Dallas, in May.
While scientists believe that high-volume injection wells may have triggered the quakes in Venus, they have not yet worked out a specific mechanism behind the Dallas and Irving quakes.
“We don’t think they’re natural,” SMU seismologist Heather DeShon told The Dallas Morning News. “But we don’t understand the subsurface physics surrounding the Irving earthquake sequence, so we’re still considering all causes.”
DeShon’s comments came during the annual American Geophysical Union meeting in San Francisco, where she and her colleagues presented their latest research on North Texas ground shaking. The research has not yet been independently vetted and published.
“Any discussion of causation for the Dallas-area quakes is premature, and more speculative than scientific,” said Steve Everley, a senior advisor for Energy In Depth, a program of the Independent Petroleum Association of America. “But the SMU team has helped advance our understanding of the conditions that can ultimately lead to induced seismicity, so we’re eager to see what they will publish about the seismic events near Dallas.”
Evidence that human activity is behind the Dallas quakes includes a new analysis showing that the faults beneath Dallas and Fort Worth had been dormant for hundreds of millions of years until 2008, the year felt earthquakes first began rumbling through the area. . . .
Earlier this week, SMU seismologist Beatrice Magnani compared North Texas faults with those known to have produced earthquakes over geologic time. Active faults have visible ruptures, while the small faults that the SMU team has mapped in Azle and Venus have barely perceptible ones.
Unlike historically active faults, those in North Texas also do not extend into the uppermost layers of sediment. Faults that have been active over hundreds of millions of years typically disturb the uppermost layers of the Earth’s crust, said Magnani.
“Those faults are dead, and they have just been rejuvenated. That is the most reasonable conclusion,” said Magnani, referring to the faults beneath North Texas. . . .
DeShon and her colleagues pointed to the absence of earthquakes in the Dallas-Fort Worth area prior to 2008 as additional evidence that recent tremors are caused by industrial activity. Since 2008, North Texas has had 200 earthquakes large enough to be included in the U.S. Geological Survey’s catalog. Thirty-one quakes have been larger than 3-magnitude.
Magnani said the state’s earthquake rate is on track to be a factor of 20 greater than historic levels. That pales in comparison to Oklahoma, which has seen a 600-fold increase in quakes. Oklahoma’s geological survey said in April that its quakes are triggered by the injection of wastewater from oil and gas operations into deep wells. Studies have found that pressure from the injections can, in rare cases, disturb deep faults. . . .