Crude oil storage tanks are seen from above at the Cushing oil hub, appearing to run out of space to contain a historic supply glut that has hammered prices, in Cushing, Oklahoma, March 24, 2016. Oil producers around the country enticed by crude’s jump to $50 a barrel are hoping to get production back on line, but for producers in Oklahoma, new regulatory barriers may keep key parts of the state shut due to worries about earthquakes. Crude’s recent rebound will mark the first test of more stringent regulations recently implemented in Oklahoma – and already, companies are looking for workarounds. Seismic activity has soared in the state in the last five years, linked to disposal of saltwater from fracking activity. Fracking is the process of drilling down into the earth and injecting liquid at high pressure in order to extract oil or gas, which has prompted environmental concerns. […]