Tokyo/UNI : A powerful earthquake of magnitude 7.1 on the Richter scale struck the waters off the east coast of Japan's Honshu island at 8:21 pm (IST) on Saturday, according to Japan Meteorological Agency.
According to reports, no tsunami alert was issued.
The epicenter, with a depth of 50 km, was monitored at 37.70 degrees north latitude and 141.80 degrees east longitude.
''Although there may be slight sea-level changes in coastal regions, this earthquake has caused no damage to Japan,'' the agency said.
Kyodo news agency reported that 8,30,000 households in Tokyo and nearby areas are presently experiencing a blackout.