"For the past three decades, Oklahoma averaged about 50 earthquakes a year. But that number has skyrocketed in the past few years. In 2013 — the state's most seismically active year ever — there were almost 3,000."

"The quakes are small, and they're concentrated in the central part of the state, where the Erwins live.

Amanda Erwin says that even on a clear day, she knows something's up when the thunder begins: The chandelier swings, and the walls and bed start rumbling. Her husband, Keith, says the earthquakes remind him of the artillery he used to hear growing up near a military base. And when the sound and shaking fade, the game starts."

Joe Wertz reports for NPR's All Things Considered January 2, 2014. [2]