Alva Review-Courier -

WASHINGTON (AP) — A new study finds that a major trigger of man-made earthquakes rattling Oklahoma is how deep — not just how much — fracking wastewater is injected into the ground.

Scientists analyzed more than 10,000 wastewater injection wells where 96 billion gallons of fluid — leftover from hydraulic fracturing — are pumped yearly. The amount of wastewater injected and the depth are key to understanding the quake outbreak since 2009, they reported in Thursday's journal Science . The quakes included a damaging magnitude 5.8 in 2016, the strongest in state history.

State regulators could cut...