A strong earthquake with 8.5 magnitude shook buildings in Tokyo on Saturday, setting off car alarms as it rattled the Japanese capital, an AFP correspondent in the city reported.Residential buildings swayed for around a minute as the quake built in intensity at around 8.30 pm.The US Geological Survey reported a 7.8-magnitude earthquake approximately 874 kilometres (543 miles) from Tokyo in the Pacific Ocean. The Pacific Tsunami Warning Centre, which said the earthquake had a magnitude of 8.5, was at a depth of 696 kilometres.