The magnitude 7.0 aftershock came just hours after people bowed their heads and wept in somber ceremonies to mark a month since a massive earthquake and tsunami that killed up to 25,000 people and set off a crisis of radiation leaks at the nuclear plant by knocking out its cooling systems.
"Even after a month, I still cry when I watch the news," said Marina Seito, 19, a student at a junior college who recalled being in a basement restaurant in Sendai when the original 9.0-magnitude earthquake hit on March 11. Plates fell and parts of the ceiling crashed down around her.
Officials said Monday's aftershock did not endanger operations at the tsunami-flooded Fukushima Dai-ichi nuclear complex, where power was cut by the aftershock but quickly restored. The epicenter was just inland and about 100 miles (160 kilometers) north of Tokyo.
Chief Cabinet Secretary Yukio Edano told reporters that residents of five more communities, some of them more than 20 miles (30 kilometers) from the plant, were urged to evacuate within a month because of high levels of radiation. People living in a 12-mile (20-kilometer) radius around the plant already have been evacuated.
"This is not an emergency measure that people have to evacuate immediately," he said. "We have decided this measure based on long-term health risks."
Edano sounded a grave note, acknowledging that "the nuclear accident has not stabilized" and that "we cannot deny the possibility the situation could get worse."
The latest quake, the second major aftershock in less than a week, spooked people yet again in a disaster-weary northeastern Japan. Customers in a large electronics store in Sendai screamed and ran outside and mothers grabbed their children, but there were no immediate reports of more damage or injuries.
Japanese officials said the quake was a 7.0 magnitude, but the U.S. Geological Survey said it measured magnitude 6.6.
With workers still far from bringing the Fukushima Dai-ichi plant under control, the bodies of thousands of tsunami victims yet to be found and more than 150,000 people living in shelters, there was little time Monday for reflection on Japan's worst disaster since World War II.
People in hard-hit towns gathered for ceremonies at 2:46 p.m., the exact moment of the massive quake a month earlier.
"My chest has been ripped open by the suffering and pain that this disaster has caused the people of our prefecture," said Yuhei Sato, the governor of Fukushima, which saw its coastal areas devastated by the tsunami and is home to the damaged plant at the center of the nuclear crisis. "I have no words to express my sorrow."
In a devastated coastal neighborhood in the city of Natori, three dozen firemen and soldiers removed their hats and helmets and joined hands atop a small hill that has become a memorial for the dead. Earlier, four monks in pointed hats rang a prayer bell there as they chanted for those killed.
The noisy clatter of construction equipment ceased briefly as crane operators stood outside their vehicles and bowed their heads.
In the industrial town of Kamaishi, Iwate Gov. Takuya Tasso led a moment of commemoration as a loud siren rang through a high school gymnasium being used as a shelter. He bowed while people who have lived there since the tsunami kneeled on makeshift futons, bowed their heads and clasped their hands.
The school's students will return to classes Tuesday even though 129 people are living in their gym. Some, like 16-year-old Keisuke Shirato, wore their baseball uniforms for Monday's ceremony. Shirato's family was not affected by the tsunami, but about half of his teammates lost their homes.
"A new school year starts tomorrow," Shirato said. "Hopefully that will help give people hope and allow them to look toward a new start."
The earthquake and tsunami flattened communities along hundreds of miles (kilometers) of coastline, causing what the government estimates could be as much as $310 billion in damage. About 250,000 are without electricity, although some of them because of the latest two quakes Monday and last Thursday.
Adding to the misery is radiation spewing from the Fukushima Dai-ichi complex, 140 miles (220 kilometers) northeast of Tokyo. The 70,000 to 80,000 people who lived within 12 miles (20 kilometers) of the plant must stay away from their homes indefinitely.
"We have no future plans. We can't even start to think about it because we don't know how long this will last or how long we will have to stay in these shelters," said Atsushi Yanai, a 55-year-old construction worker. The tsunami spared his home, but he has to live in a shelter anyway because it is in the evacuation zone.
Plant operator Tokyo Electric Power Co. said its president, Masataka Shimizu, went to Fukushima prefecture Monday to relay his gratitude and apologies. Shimizu recently spent eight days in the hospital with dizziness and high blood pressure, but has since returned to work.
Shimizu told reporters in Fukushima that people who live near the plant are "suffering physically and mentally due to the nuclear radiation leak accident,"
"We sincerely apologize for this," he said.
At TEPCO headquarters in Tokyo, hundreds of employees bowed their heads for a moment of silence at 2:46.
Japan's government marked the one-month period by putting an ad in newspapers in China, South Korea, Russia, France, the United Kingdom and the United States - a letter from Prime Minister Naoto Kan thanking people for the outpouring of support that followed the tsunami. The Red Cross alone said it has collected $107 million (9.1 billion yen) from overseas.
Kan described the outpouring as "kizuna," the bond of friendship.
"We deeply appreciate the kizuna our friends from around the world have shown and I want to thank every nation, entity, and you personally, from the bottom of my heart."
Talmadge reported from Fukushima. Associated Press Writers Tomoko Hosaka in Kamaishi and Shino Yuasa, Mari Yamaguchi and Yuri Kageyama in Tokyo contributed to this report.
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