An unsettling weekend in Oklahoma. Seven earthquakes recorded in two days.
The largest registered a magnitude of 4.3 near Langston.
According to the U.S. Geological Survey, as of last month 207 quakes were reported in Oklahoma.
The state averaged just two per year from 1978 to 2008.
No official reason for the spike, but many environmentalists suggest the cause could be hydro-fracking -- the process of injecting a mixture of water and chemicals deep into the earth.
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