Extract from an article by Carey Gillam published by Reuters, 5 April 2014, under the headline: Series of small earthquakes rock Oklahoma in record seismic activity
(Reuters) – Earthquakes rattled residents in Oklahoma on Saturday, the latest in a series that have put the state on track for record quake activity this year, which some seismologists say may be tied to oil and gas exploration. One earthquake recorded at 3.8 magnitude by the U.S. Geological Survey rocked houses in several communities around central Oklahoma at 7:42 a.m. local time. Wastewater disposal related to the fracking is suspected by many scientists to contribute to the earthquake activity. Millions of gallons of wastewater are typically trucked from a fracking site to wells where the water is injected thousands of feet underground into porous rock layers. That work, if done near a fault, can trigger larger quakes, according to several recent scientific studies.