TOKYO, April 7 (Xinhua) — An earthquake measuring 7.4 on the Richter scale jolted Japan’s Miyagi Prefecture and its vicinity in northeastern Japan at 23:32 p.m. (1432 GMT) local Time Thursday, the Japan Meteorological Agency (JMA) said.
The JMS earlier issued tsunami warning following the strong quake, but the alert was lifted later.
The focus of the quake was located some 40 km under the sea off the northeastern prefecture, where has been devastated by the March 11 earthquake, said the agency.
Xinhua’s office building in Tokyo swayed for a while when the quake occurred.
The JMA considered the quake as the aftershock of the devastating quake last month.
The quake has not brought further damage to the nuclear power plants in Fukushima Prefecture so far, according to Tokyo Electric Power Co. However, engineers stepping up efforts to fix the troubled Fukushima nuclear power plant have been evacuated following the strong tremor late on Thursday, Tokyo Electric officials told a televised news conference.
According to Kyodo news reports, blackouts were seen all over Aomori, Iwate and Akita prefectures as well as several parts of Miyagi and Yamagata prefectures, according to the nuclear regulator.
Nuclear power stations in Ibaraki Prefecture were operating normally after the quake, while at the Onagawa nuclear plant in Miyagi Prefecture, which has been suspended, two external power supply units among three have failed, according to the nuclear regulator.
Tohoku Electric Power Co. said, meanwhile, external power supply was disrupted at the No. 1 reactor of the Higashidori nuclear station. The emergency generator is being used to cool the spent fuel pool.
According to Japanese Deputy Chief Cabinet Secretary Tetsuro Fukuyama, conditions at Tohoku Electric Power Co Inc’s Onagawa nuclear plant in Miyagi prefecture are safe following the strong aftershock in the area late on Thursday.
In Miyagi Prefecture, expressways were closed due to the quake.
In Rokkasho, Aomori Prefecture, external power supply was disrupted at the spent nuclear fuel reprocessing plant of Japan Nuclear Fuel Ltd. The emergency generator is being used there, Kyodo said.
The crisis at the Fukushima Daiichi power station started after the March 11 killer earthquake and tsunami. Strong aftershocks continued after the quake.
At the crippled Fukushima Daiichi nuclear power plant, radiation in seawater near the No. 2 reactor remains high, even after the leakage of contaminated water into the sea was stopped. Tokyo Electric Power Company said it detected 5,600 bequerels of radioactive iodine-131 per cubic centimeter in seawater samples collected around the water intake of the reactor at 7:40 am local time on Wednesday. That is about 140,000 times higher than the safety limit under the government’s standards.
A 9.0-magnitude earthquake shook the Pacific coastal areas of northeastern and eastern Japan on March 11, triggering enormous tsunami.
According to the National Police Agency, the twin disasters had left 12,468 people dead and 15,091 others unaccounted for in Japan by 10: 00 a.m. Wednesday.