Finally a study has shown what those of us that have lived in seismically unstable areas learned in grade school. Pressure on faults causes earthquakes. In this case the pressure of putting fracking waste water into the ground causes those fault lines to move.
The study says that there is a direct correlation between putting fluid into the ground and increased seismicity. It uses the occurrence of larger quakes elsewhere to show that faults that normally are quite stable and less likely to be affected by plate motion are moving because of the presence of pressurized fracking waste water. These fluids change the dynamics of the fault by providing space for excess slippage that would not normally occur.
Pumping water underground at geothermal power plants can lead to dangerous earthquakes even in regions not prone to tremors, according to scientists. They say that quake risk should be factored into decisions about where to site geothermal plants and other drilling rigs where water is pumped underground – for example in shale gas fracking.
Prof Emily Brodsky, who led a study of earthquakes at a geothermal power plant in California, said: "For scientists to make themselves useful in this field we need to be able to tell operators how many gallons of water they can pump into the ground in a particular location and how many earthquakes that will produce."
It is already known that pumping large quantities of water underground can induce minor earthquakes near to geothermal power generation and fracking sites. However, the new evidence reveals the potential for much larger earthquakes, of magnitude 4 or 5, related to the weakening of pre-existing undergrounds faults through increased fluid pressure.
"[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."So damage in places that rarely see earthquakes that can be easily detected can be attributed to the ecological damage caused by fracking.
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.