A strong earthquake measuring 6.8 on the Richter scale jolted Japan's northeastern Honshu island at 2: 36 p.m. local time and triggered a 50 cm tsunami advisory for Miyagi and Fukushima prefectures, the country's weather agency said.

No abnormalities have been observed in Fukushima No. 1 nuclear plant following the quake as of press time, according to the operator Tokyo Electric Power Co.(TEPCO).

The quake, with its focus off Fukushima coast with a depth of 20 km, was strongly felt in Fukushima and Miyagi prefectures, causing the Shinkansen bullet train in the region to suspend service and expressways to be closed.

The region suffered severe damage from a massive quake and tsunami in March and triggered the a nuclear crisis in Fukushima.