The epicentre of the quake was east of Russia's Kuril Islands at 56.7 kilometres of depth, according to the US Geological Survey.
The quake was initially reported as magnitude 7.8.
On Wednesday afternoon (local time), Russia's far east region was jolted by a 7.5 magnitude natural disaster, but no casualties were reported at the time of the press.
The Pacific Tsunami Warning Center said hazardous tsunami waves were possible within 1,000 kilometers (600 miles) of the quake's epicenter.
A magnitude 7.6 quake occurred some 500 kilometers (300 miles) from the Russian Far Eastern city of Petropavlovsk-Kamchatsky, the Kamchatka office of the Geophysical Service of the Russian Academy of Sciences said.
Update: Just before midnight CDT, the U.S. Tsunami Warning Center issued an updated statement. However, it noted that some of these areas may experience non-damaging sea-level changes.
The Japan Meteorological Association also said there might be slight tidal changes but said no warnings or even watch advisories had been issued.
This is a developing story.