HONG KONG: A powerful 7.3 earthquake that struck off Japan's northeastern coast Friday did not generate a Pacific-wide tsunami, a US early warning agency said.
There was no threat of a tsunami in the wider Pacific Ocean, according to the US-based Pacific Tsunami Warning Center, but it warned an earthquake of that magnitude could generate a tsunami that can be destructive for local coastlines.
However, Japanese authorities issued a tsunami alert for the northeast coast after undersea earthquake struck, setting buildings in Tokyo swaying violently.
Media reports said a one-metre-high wave could sweep ashore in an area badly hit by the March 2011 tsunami that devastated a large swathe of the northeast coast, killing thousands.
Residents of at least one town, Minamisanriku in Miyagi prefecture, were advised to evacuate to higher ground, reports said, suggesting other towns were also affected.
It was not possible immediately to confirm the reports, with telephone operator NTT saying the network was jammed with the weight of callers.
A presenter on state broadcaster NHK repeatedly told viewers to get to safety.
"Remember last year's quake and tsunami," he said. "Call on your neighbours and flee to higher ground now!"
NHK, quoting the national meteorological agency, said the tsunami was expected to hit the coast of Iwate at 5:40pm (0840 GMT), Fukushima at 5:50pm, and Aomori and Ibaraki at 6:00pm.
The United States Geological Survey measured the quake's magnitude at 7.3. It said the tremor struck a relatively deep 36km under the Pacific.
The epicentre was 284km east of Sendai, or 459km northeast of Tokyo, according to the USGS. - AFP