A 6.6-magnitude aftershock rattled Japan today on the one-month anniversary of the twin disasters that left at least 25,000 dead and officials scrambling to prevent a meltdown at damaged nuclear reactors.
A 3-foot tsunami warning was issued after the temblor hit the northeast coast 5:16 p.m. local time. All advisories and warnings were lifted about an hour later, according to local Japanese TV.
Japanese officials reported the aftershock at 7.1 before downgrading it to 7.0, but the U.S. Geological Survey said the quake was closer to a magnitude 6.6.
The epicenter of the quake was the Fukushima area but it was felt across a widespread area, officials said.
The same general region was hit Thursday by a 7.1 quake, which shutdown two Japanese nuclear plants and triggered a tsunami warning.
The aftershock comes as the country observed moments of silence and reflected on the devastating 9.0-magnitude earthquake and tsunami that hit Japan March 11.
Officials are trying to recover the thousands of bodies still trapped in the rubble and to contain the radiation at the Fukushima Daiichi nuclear plant located about 140 miles northeast of Tokyo.
The plant reactor's cooling system was damaged and officials have been trying to repair it and cool the rods by pouring seawater over them.
The Tokyo Electric Power Company (TEPCO), the company that operates the Fukushima plant, said it evacuated its workers but reports that there are no damage or irregularities at the complex in a news conference shortly after today's aftershock.
But TEPCO officials said the quake briefly cut off the external power supply to reactors No. 1 to 3 and water injections at the plant have been temporarily halted.
Earlier, some evacuees around the damaged nuclear reactor had been pressuring the government to let them return home to at least get their belongings.
But there's still concern about long-term radiation exposure.
"Even if there are no new discharge of radioactive materials already, there's deposition on the soil, which may affect people who remain in the area for a long time," Yukio Edano, Japan's chief cabinet secretary, said on Japanese television today.
"It may have some affects on people's health."
Edano later said in a news conference that people living in four areas, about 20 miles from the plant, should leave the region within a month, according to the Associated Press.
Residents living within 12 miles of the plant have previously been told to evacuate.
Hidehiko Nishiyama, a nuclear safety official, said there is still no word on a timeline to "resolve the problem."
"We are very sorry for the evacuees who are anxious to see the problem resolved," Nishiyama told the Associated Press today.
While officials work to contain radiation at Fukushima, production is restarting at auto plants.
Toyota restarted production Friday at its plants in Japan.
Honda is reopening two of its plants today, good news for Japan's businesses to get back on track.
"Electricity is an issue, transportation, water and getting the workers to and from the plants are all very important," Detroit-based analyst John Clor told ABC News Radio. "And the fact that Honda can resume some production at least means that the infrastructure is getting back into place, which is a good sign."
The Associated Press contributed to this report.