The U.S. Geological Survey will soon confirm that the oil and gas industry is creating earthquakes, and new data from the Midwest finds that these man-made quakes are happening more often than originally thought.
Earthquakes happen when faults in the Earth slip and slide against each other. There's continuous stress on innumerable faults on our continent, but seismologists like Bill Ellsworth, from the U.S. Geological Survey, started seeing something odd about 12 years ago.
"One thing we had begun to notice was that there were an unusual number of earthquakes in the middle of the country," he says, an area not known for quakes. They were small, though — usually just over magnitude 3. Then, in 2009, the shaking got much more frequent.
