Distant earthquakes trigger tremors at U.S. waste-injection sites, says study

Large earthquakes from distant parts of the globe are setting off tremors around waste-fluid injection wells in the central United States, says a new study. Furthermore, such triggering of minor quakes by distant events could be precursors to larger events at sites where pressure from waste injection has pushed faults close to failure, say researchers. Among the sites covered are central Oklahoma, western Texas and southern Colorado.
Source: http://www.sciencedaily.com/releases/2013/07/130711142401.htm