A magnitude 6.3 earthquake hit the prefecture of Haixi in Qinghai, a province in northwest China, with a depth of 10 km, the China Earthquake Networks Center reported on Tuesday.There were no immediate reports of casualties or damage and local authorities were assessing the situation, state broadcaster CCTV reported.The quake struck the high-altitude area at 5:06 p.m. Beijing time (0906 GMT) on Tuesday, according to CENC. Several aftershocks were detected, including one measured at a magnitude of around 5.