UPDATE1: Strong quake jolts Miyagi Pref. and vicinity, tsunami warning lifted+

TOKYO, April 8 Kyodo -
(EDS: ADDING INFO)
A strong quake with a preliminary magnitude of 7.4 jolted on Thursday evening Japan's Miyagi Prefecture and its vicinity but no major troubles were reported at nuclear facilities in the areas devastated by the March 11 earthquake, including the crippled Fukushima Daiichi power station.
The Japan Meteorological Agency issued a tsunami warning immediately after the 11:32 p.m. quake, whose seismic center was off Miyagi Prefecture at a depth of some 40 kilometers, but it was lifted shortly before 1 a.m. Friday.
There were many emergency calls about injured people, fires and gas leakage, according to local police and fire departments.
The National Police Agency said seven people have been injured so far in Iwate, Akita, Yamagata and Fukushima prefectures.
The quake measured upper 6 on the Japanese seismic intensity scale of 7 in Kurihara and Sendai in Miyagi Prefecture and lower 6 in Ofunato, Kamaishi, Ichinoseki and several other cities in Iwate Prefecture as well as some other parts of Miyagi, according to the agency.
In Kurihara, a residential building collapsed, injuring an 85-year-old woman, according to the local fire department.
Blackouts occurred all over Aomori, Iwate and Akita prefectures as well as several parts of Miyagi and Yamagata prefectures, according to the Nuclear Industrial Safety Agency.
Tohoku Electric Power Co. said operations of five units at three thermal plants in Aomori and Akita prefectures were suspended.
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 said 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.
A Nuclear and Industrial Safety Agency official said Friday that it appears that the reactor systems are basically working ''as designed'' because emergency diesel generators are operating in reactors that lost external power.
In the March 11 quake and ensuing tsunami, most of the backup diesel generators did not work at the Fukushima Daiichi nuclear power plant, and thus resulted in the loss of the key cooling functions of the plant's reactors.
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.
Restoration work at the Fukushima Daiichi plant continued following the quake and no additional leaks of radioactive substances have been confirmed, TEPCO said.
In Miyagi Prefecture, expressways were closed due to the quake, while the bullet train services on the Tohoku and Tokaido shinkansen lines were partially suspended.
The crisis at the Fukushima Daiichi power station started after the March 11 killer earthquake and tsunami.
While strong aftershocks continued after the March 11 quake, it was the first time that an aftershock registered upper 6 on the Japanese seismic intensity scale.
Prime Minister Naoto Kan instructed relevant agencies and ministries to make their utmost efforts to rescue the quake-hit people before moving to his office from his official residence.
He told reporters, ''I need to examine what has happened.''
Deputy Chief Cabinet Secretary Tetsuro Fukuyama told reporters after 1:30 a.m. that there are no notable changes in radiation levels near the Fukushima nuclear complex, which has been at the center of the urgent situation for about a month.
Fukuyama, however, said the damage from the latest quake is likely to expand.
==Kyodo