Horses nuzzle near a seismometer deployed in a pasture near an earthquake epicenter in Sparks, Okla. A 5.6-magnitude earthquake shook near here in November 2011, the state's largest earthquake in a century.

Joe Wertz / StateImpact Oklahoma

Earthquakes Are on the Rise in Oklahoma, and Researchers Are Asking Why

  • Joe Wertz

Joe Wertz / StateImpact Oklahoma

Horses nuzzle near a seismometer deployed in a pasture near an earthquake epicenter in Sparks, Okla. A 5.6-magnitude earthquake shook near here in November 2011, the state's largest earthquake in a century.

More than 1,000 earthquakes were recorded in Oklahoma in 2010. The next year, there were more than 1,400 earthquakes, making 2011 the state’s most seismically active year on record.

A 5.6-magnitude quake was recorded that year — Oklahoma’s largest in at least a century — and researchers, regulators and the public are starting to ask questions about the state’s seismic risks.