(Kyodo) — A powerful quake with a preliminary magnitude of 7.5 struck northeastern Japan late Monday night, with the weather agency issuing a tsunami warning for coastal areas of Hokkaido as well as Aomori and Iwate prefectures before downgrading it hours later.
The Japan Meteorological Agency also said the quake, which occurred at 11:15 p.m. off Aomori’s Pacific coast at a depth of 54 kilometers, raises the chance of a quake of a similar or even larger magnitude hitting the same area within the coming several days.
It is the first time the agency has issued such an alert for the coastal regions of Hokkaido and the Sanriku coast, which extends from Aomori through Iwate and Miyagi prefectures.
The Cabinet Office called on the public to maintain special readiness for at least a week, such as by keeping an emergency supply kit within reach so they can evacuate at a moment’s notice if necessary.
The quake occurred in an area along the trench running off the coast of Hokkaido and northeastern Japan, where the government warns of major quakes caused by the Pacific plate subducting beneath the Honshu main island, according to the agency.
The M9.0 megaquake in 2011, which left nearly 20,000 people dead and over 2,500 missing and triggered the Fukushima nuclear disaster, also occurred off northeastern Japan.
The agency, which revised the magnitude from the initially reported 7.2, warned of tsunami of up to 3 meters following the quake. The highest tsunami observed so far has been about 70 centimeters in Iwate.
Three and a half hours after the quake struck, the tsunami warning was downgraded to an advisory.
The quake logged an upper 6 on the Japanese seismic intensity scale of 7 in parts of Aomori. It was felt in central Tokyo.
The Japanese government was checking for injuries and property damage, Chief Cabinet Secretary Minoru Kihara said in a press conference in the early hours of Tuesday. Defense Minister Shinjiro Koizumi separately told reporters that Self-Defense Force aircraft had been deployed to collect information in northeastern Japan.
In Aomori and Hokkaido, there have been reports of several non-life-threatening injuries. The Aomori prefectural government said that around 2,700 homes were left without power.
No abnormalities have been reported by nuclear plants in Hokkaido or the northeastern prefectures of Aomori, Miyagi and Fukushima. The government also confirmed there were no abnormalities at a nuclear fuel reprocessing plant in Rokkasho, a Pacific coastal village in Aomori Prefecture.
Tohoku Shinkansen bullet train services have been halted between Fukushima and Shin-Aomori stations, operator JR East said. A bullet train carrying 94 passengers was briefly stranded in Aomori.