Even in regions not predisposed to earthquakes, filling wells with waste injection fluids can lead to dangerous tremors, scientists say.
The wells are at greater risk for small quakes triggered by larger tremors after being filled with waste produced by oil and gas fields.
Waves from high-magnitude earthquakes travel distances through Earth's crust, "squeez[ing] rock formations like a sponge," said Nicholas van der Elst, the lead author on the Columbia University research.
The waves open new passageways for fluids to get into faults and weaken them, he said. For decades, sites in Oklahoma, Texas and Colorado have practiced wastewater well injection. Tremors there came as early as six months after injection. Volcanic activity has been known
Further research may change how companies to decide where dispose of wastewater for geothermal plants and other drilling rigs where water is pumped underground, like in shale gas fracking, based on the risk for earthquakes.
"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," said Emily Brodsky.
Scientists had already discovered that pumping water underground causes small earthquakes. But now, they say the quakes could be more intense than expected, with magnitudes of 4 or 5.
Brodsky said there is a direct correlation between the amount of water extracted and injected into the ground and the number of earthquakes.
The EPA just dropped a study of depositing waste from fracking that was alleged to be contaminating water in Wyoming. At first, the EPA began studies to ensure that groundwater was safe despite fracking. Amid questions of its methodology, the EPA has ended its study and decided not to release the data collected.