Following a cluster of events near Oklahoma shale basins, data from the U.S. Geological Survey show nearly two dozen small tremors in the last week. A magnitude-2.5 event recorded midday Sunday in Medford, near the northern Oklahoma border with Kansas, was one of 22 smaller tremors recorded in the state in the last week. USGS data show the largest event was a magnitude-3.7 quake reported in Medford on Wednesday. Oklahoma Gov. Mary Fallin last week issued a declaration of emergency after a magnitude-5.0 event struck Cushing, the central U.S. storage hub for crude oil. “Two years ago, we established the coordinating council on seismicity,” she said. “Regulators continue to target areas for additional scrutiny that are experiencing increased seismic activity, […]