A magnitude 7.5 earthquake struck in the middle of Papua New Guinea on Sunday, the U.S. Geological Survey said. The quake struck about 55 miles southwest of Porgera in the Pacific island nation at a depth of about 23 miles, according to the agency. No tsunami watches or warnings were issued from the quake, and there were no immediate reports of injuries. The Geological Survey website had 19 reports of feeling the quake, including some saying the shaking was violent.