Hong Kong/Beijing CNN  —  A light earthquake rattled Beijing overnight, waking residents and sending students rushing from their dorms as videos of shaking living rooms went viral on Chinese social media on Wednesday. The 4.5-magnitude quake struck a suburb of the nearby port city of Tianjin at 01:21 a.m. local time at a depth of 10 kilometers (6.2 miles), according to the United States Geological Survey (USGS). The China Earthquake Networks Center measured the quake at a magnitude of 4.2 and a