Earlier this year, the U.S. Geological Survey raised its official earthquake risk level for Texas, a decision that would have been surprising until a few years ago.

But in the last eight years, Texas has experienced more than 150 earthquakes. Startlingly, these earthquakes are man-made, caused by injecting wastewater from oil and gas production into disposal wells. Numerous studies have found that pumping such huge volumes of wastewater into the ground can cause existing faults to move, triggering earthquakes.

Austin American-Statesman