The meteorological agency said a series of quakes hit the country's east on Friday, including one with a magnitude of 5.7 which struck in the Pacific Ocean off Ibaraki prefecture, some 100 kilometres northeast of Tokyo.

There was no risk of a tsunami, the agency said.

A series of strong earthquakes hit the Tokyo area on Thursday, briefly cutting off power to more than 4,000 homes and causing light injuries.

Located in the same area off Ibaraki, the biggest quake on Thursday was initially recorded at 6.7 but was later revised up to 7.0.

Japan experiences 20 percent of the world's major earthquakes and has developed an infrastructure meant to withstand violent tremors.

The nation lies at the crossing of four tectonic plates and is constantly bracing for the dreaded 'Big One' feared to inflict major damage. -- AFP