<p>The tremors follow a major 7.3 quake yesterday which swayed buildings in Tokyo and triggered a small tsunami but did not cause any casualties or property damage.<br /><br />The latest was a 6.8-magnitude quake that hit at 6:24 am (local time yesterday), 400 kilometres northeast of Tokyo at a shallow depth of nine kilometres below the Pacific seafloor, the Japan Meteorological Agency said.<br /><br />The tremor prompted the agency to issue a tsunami warning which was soon lifted.<br /><br />That came three hours after a 6.2-magnitude quake in the same region and another one measuring 6.1 yesterday's quake and the early today aftershocks were all in the same area.<br /><br />There were no reports of major damage or casualties, local police said.<br />"We do not have to worry about a tsunami now but should be on alert for more aftershocks following yesterday's earthquake," an official at the Japanese agency said.<br /><br />Around 20 per cent of the world's most powerful earthquakes strike Japan, which sits on the "Ring of Fire" surrounding the Pacific Ocean.<br /><br />Tectonics experts have warned of a 70 percent chance that the "Big One" -- a magnitude-seven earthquake or worse -- will strike the greater Tokyo region, home to around 35 million people, within the next 30 years.</p>
<p>The tremors follow a major 7.3 quake yesterday which swayed buildings in Tokyo and triggered a small tsunami but did not cause any casualties or property damage.<br /><br />The latest was a 6.8-magnitude quake that hit at 6:24 am (local time yesterday), 400 kilometres northeast of Tokyo at a shallow depth of nine kilometres below the Pacific seafloor, the Japan Meteorological Agency said.<br /><br />The tremor prompted the agency to issue a tsunami warning which was soon lifted.<br /><br />That came three hours after a 6.2-magnitude quake in the same region and another one measuring 6.1 yesterday's quake and the early today aftershocks were all in the same area.<br /><br />There were no reports of major damage or casualties, local police said.<br />"We do not have to worry about a tsunami now but should be on alert for more aftershocks following yesterday's earthquake," an official at the Japanese agency said.<br /><br />Around 20 per cent of the world's most powerful earthquakes strike Japan, which sits on the "Ring of Fire" surrounding the Pacific Ocean.<br /><br />Tectonics experts have warned of a 70 percent chance that the "Big One" -- a magnitude-seven earthquake or worse -- will strike the greater Tokyo region, home to around 35 million people, within the next 30 years.</p>