Was the 4.4-magnitude earthquake that rattled Los Angeles on Monday morning caused by fracking methods? It's hard to say, but what's clear from the above map, made by Kyle Ferrar of the FracTracker Alliance, is that the quake's epicenter was just eight miles from a disposal well where oil and gas wastewater is being injected underground at high pressure.
Don Drysdale, spokesman for the state agency that oversees California Geological Survey, told me that state seismologists don't think that the injection well was close enough to make a difference (and the agency has also raised the possibility that Monday's quake could have been a foreshock for a larger one). But environmental groups aren't so sure.
In other states, injection wells located 7.5 miles from a fault have been shown to induce seismic activity, points out Andrew Grinberg, the oil and gas project manager for Clean Water Action. "We are not saying that this quake is a result of an injection," he adds, "but with so many faults all over California, we need a better understanding of how, when, and where induced seismicity can occur with relation to injection."
"Shaky Ground," a new report from Clean Water Action, Earthworks, and the Center for Biological Diversity, argues that the close proximity of such wells to active faults could increase the state's risk of earthquakes. According to the report, more than half of the state's permitted oil wastewater injection wells are located less than 10 miles from an active fault, and 87 of them, or about 6 percent, are located within a mile of an active fault.