A recent study done by Columbia University and the University of Oklahoma published in the 12 July 2013 issue of Science suggests that large (magnitude 7 or above) earthquakes from all over the globe can trigger smaller quakes at waste fluid injection sites where pressure from the fluids has pushed faults close to failure. At some injection locations, a swarm of remotely triggered earthquakes appears to act as a warning sign that large earthquakes related to human activities may be imminent. Several areas in Oklahoma, Colorado, and Texas showed this correlation.

At one of the studied waste injection sites, in Prague, OK, a magnitude-8.8 earthquake off the coast of Chile on February 27, 2010 helped to trigger a notable swarm of earthquakes, which was followed by a human-induced magnitude-5.7 earthquake in Prague on November 6, 2011. Similarly, earthquakes off the coasts of Japan and Sumatra in 2011 and 2012, respectively, set off swarms of earthquakes that were later followed by mid-sized earthquakes at injection sites in western Texas and southern Colorado. Other sites with induced earthquakes did not respond to the passage of seismic waves from remote earthquakes.

The sites that reacted to stresses caused by remote earthquakes all had a decades-long history of injection, are assumed to have been near critically stressed faults, and had low levels of seismicity before the triggered earthquakes.

A separate paper in the same issue of Science, authored by William Ellsworth of the U.S. Geological Survey, provides a wide-ranging review of injection-induced earthquakes.