TOKYO, April 20 (Xinhua) -- The magnitude of the earthquake that struck northeastern and northern Japan on Monday afternoon has been revised up to 7.7 from 7.5, according to the Japan Meteorological Agency (JMA).
Tsunami waves have been observed off the Pacific coasts of Hokkaido, Aomori and Iwate prefectures, with Kuji Port in Iwate Prefecture recording an 80-cm wave, while Miyako Port, also in the prefecture, measured a 40-cm wave.
A man in his 60s in Hachinohe, Aomori Prefecture, has been taken to the hospital after falling down the stairs at his home, Kyodo News reported, citing the local fire department.
According to the Ministry of Internal Affairs and Communications, evacuation orders have been issued for more than 170,000 people in Hokkaido, Aomori, Iwate, Miyagi and Fukushima prefectures, with residents in the affected areas urged to move to higher ground.
No abnormalities have been reported so far at the Higashidori and Onagawa nuclear plants in Aomori and Miyagi prefectures, respectively, or at the Fukushima Daiichi and Daini nuclear power plants in Fukushima Prefecture, according to their operators.
The earthquake has disrupted transportation, including the suspension of Tohoku Shinkansen bullet train services between Tokyo and Shin-Aomori stations.
The powerful temblor occurred at 4:53 p.m. local time on Monday off the Sanriku coast at a depth of 20 km, measuring upper 5 on Japan's seismic scale of 7 in the hardest-hit areas in Aomori Prefecture, said JMA.
The quake's epicenter was located at a latitude of 39.8 degrees north and a longitude of 143.2 degrees east. Its magnitude was initially estimated to be 7.4 but was later revised up twice.
Shortly after the quake, the weather agency warned of similarly strong quakes within the coming week. ■
