(Discovery) Oklahoma has been a little shaky lately. On Aug. 19, the Sooner State was rattled by 20 earthquakes in one day, according to data from Oklahoma’s Geology Survey. It’s the latest manifestation of a significant increase in seismic activity in Oklahoma, which scientists believe is being caused by hydraulic fracturing, AKA fracking, to tap into oil and gas under the surface, and by the injection of wastewater from oil-gas wells into brine reservoirs underground.

While most of the quakes were so small — below a magnitude of 3 — that Oklahoma residents may barely have noticed them, the 10,000 inhabitants of Guthrie, Okla. definitely felt the 4.3 quake that rattled their small city at 7:45 a.m. The vibrations caused a local newscaster to raise her hands in the midst of a segment and shout, “earthquake!”

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