Huge quakes may foretell smaller, human-caused ones
Distant powerful temblors triggered ominous activity at wastewater injection sites
Over the last few years, the number of earthquakes in the central and eastern United States has increased along with the rise in wastewater disposal wells associated with fracking. The map shows all of the magnitude 3 or greater earthquakes that occurred in the United States in 2009-2012. Places with the highest natural earthquake hazards are shown in red and orange while areas with lower risk are shown in yellow and green.
Courtesy of Science/AAAS