But the meteorological agency lifted the warning about an hour after the latest jolt hit at 6:51 am (2151 GMT Wednesday) some 50 kilometres (31 miles) off the east coast of Miyako, Iwate prefecture, at a depth of 20 kilometres in the Pacific.
USGS also registered the quake at 6.7 in magnitude at a depth of 32 kilometres.
The Japanese agency had warned that a 50 centimetre (20-inch) tsunami could be expected in the region, but no warning was issued to Fukushima at the centre of the nation's nuclear crisis.
Public broadcaster NHK reported there were no immediate reports of damage from the quake while no sizable high waves were seen.
Shinkansen bullet train services were temporarily suspended, while there was no new damage to the Onagawa nuclear power plant in Miyagi, south of Iwate, which has been out of operation since the March 11 disaster, NHK added.
The northeast coast of Japan's main Honshu island was ravaged by a 9.0 magnitude quake and monster tsunami on March 11 which left some 23,000 people dead or missing.
The disasters also crippled the Fukushima Daiichi nuclear power plant, triggering the world's worst atomic accident since Chernobyl in 1986 and forcing hundreds of thousands of residents to leave their homes.
source:
http://sg.news.yahoo.com/japan-issues-tsunami-alert-following-strong-quake-221952459.html