Yes, but the earthquakes are caused by a related part of the oil and gas production process, not hydraulic fracturing itself. While there have been a few cases in which fracking has caused small earthquakes, the rise in property-damaging earthquakes has occurred as a result of large volumes of wastewater being injected into disposal wells—special-purpose wells that don’t produce oil or gas but store industrial waste.
We asked Daniel Raimi, senior research associate at Resources for the Future and author of “The Fracking Debate: The Risks, Benefits, and Uncertainties of the Shale Revolution” (Columbia University Press), to explain why we have seen a large increase in the number of human-caused earthquakes, particularly in Oklahoma.
Raimi said: Oklahoma is where they have seen the biggest problems. The reason we’ve seen such a large increase in the number of earthquakes there is because of the geology in Oklahoma. Other big shale plays have not seen large increases in earthquakes even though they are also disposing of large volumes of wastewater.
In addition, policy makers in Oklahoma were relatively slow to respond to the problem. They had their first big earthquake in 2011—a 5.6—but it wasn’t until 2015 that the state put meaningful policies into place to try to reduce the risks from wastewater injection. [Meanwhile, the number of earthquakes in Oklahoma rose from 41 in 2010 to 579 in 2014 to 903 in 2015].
Going forward there are strategies that Oklahoma and other states are employing to reduce earthquakes.
First, they are trying to do a better job of mapping underground fault networks so they can understand where you might not want to inject wastewater because there’s a pretty significant fault that could be activated.
Second, states are putting into place detailed seismic monitoring networks so they can put devices around oil and gas producing regions to measure with great accuracy any small seismic events that might not be picked up by the larger U.S. Geological Survey instruments.
The small quakes are often precursors to larger quakes and this is where policy comes into play. There are a number of places [including Oklahoma] that have implemented what are called “traffic light” systems where if the state detects a small earthquake—say, 1.5 or 2.0 in magnitude—then [the disposal well operator] is given a yellow light that says proceed with caution with your wastewater injection or hydraulic fracturing activity.
If they then see a larger quake—say, magnitude 2.5—then there is a red light which says you need to stop all activities immediately until the state and the operator can figure out what’s going on and reassess the situation.
But it’s unlikely they are going to eliminate the risk entirely because the subsurface is extremely complex and it’s unlikely they are going to understand every nook and cranny that could contribute to an earthquake. But they can reduce the risk of large-scale earthquakes.