A powerful magnitude 7 earthquake has struck China’s Tibet region, killing at least 16 people, injuring 54 and collapsing hundreds of homes in and around the northern city of Nagqu, official media reported.The quake hit at 10:33 p.m. local time on Thursday, with its epicentre 191 kilometres east-northeast of Nagqu in a sparsely populated, high-altitude area of northern Tibet, according to the US Geological Survey.It was the most powerful earthquake to strike the region in five years, China’s state broadcaster CCTV said.At least 339 homes and 20 livestock sheds collapsed, according to the Nagqu media office.Chinese President Xi Jinping called for all-out efforts in rescue and medical relief operations.Thus far, more than 1,600 people have been deployed for search and rescue operations, with emergency supplies including 1,000 prefabricated housing units, 3,000 tents, folding beds, flashlights and winter clothing delivered to the area.Aftershocks, rockfalls and disruptionThe USGS recorded at least seven aftershocks ranging in magnitude from 4.3 to 5.2, all at a depth of 10 kilometres. The main quake struck at a depth of 18 kilometres.Rockfalls triggered by the earthquake forced authorities to close a section of National Highway 317 to all but emergency, rescue and official vehicles while crews worked to clear debris. Local railway authorities halted train services through the affected area as a precaution.China’s state news agency Xinhua reported that communication has been cut in some areas hit by the quake.Intermittent snow is forecast across the earthquake zone over the next three days, complicating rescue efforts.Nagqu lies more than 300 kilometres north of Lhasa, Tibet’s capital.