As a geologist, I often get questions about fracking. In Oklahoma, many small earthquakes have plagued residents and kept them on edge wondering why the sudden surge in seismicity. One of the large quakes has been linked to wastewater fluid injection (not fracking) and this inadvertant release of stress may have stressed another area leading to a responding quake.
In a new study involving researchers at the U.S. Geological Survey, scientists observed that a human-induced magnitude 5.0 earthquake near Prague, Oklahoma in November 2011 may have triggered the larger M5.7 earthquake less than a day later. This research suggests that the M5.7 quake was the largest human-caused earthquake associated with wastewater injection.
“The observation that a human-induced earthquake can trigger a cascade of earthquakes, including a larger one, has important implications for reducing the seismic risk from wastewater injection,” said USGS seismologist and coauthor of the study Elizabeth Cochran.
The research published this week suggests that the foreshock, by increasing stresses where M5.7 mainshock ruptured, may have triggered the mainshock, which in turn, triggered thousands of aftershocks along the Wilzetta fault system, including a M5.0 aftershock on November 8, 2011. If this hypothesis is correct, the M5.7 earthquake would be the largest and most powerful earthquake ever associated with wastewater injection.
Humans do affect the earth. We must be diligent and learn from our actions so this won’t domino into something really bad.
The paper detailing this idea, because that’s how science works, not by speculation, has been published in the Journal of Geophysical Research. It will now be critiqued by others and compared to potentially related events around the world.