RIKUZENTAKATA, Japan » Through silence and prayers, people across Japan remembered the massive earthquake and tsunami that struck the nation one year ago today, killing just over 19,000 people and unleashing the world’s worst nuclear crisis in a quarter century.

A moment of silence was observed at 2:46 p.m. — the exact time the magnitude-9.0 quake struck on March 11, 2011.

In the devastated northeastern coastal town of Rikuzentakata, a siren sounded and a Buddhist priest in a purple robe rang a huge bell at a damaged temple overlooking a barren area where houses once stood.

At the same time in Tokyo’s National Theater, Emperor Akihito, Empress Michiko and Prime Minister Yoshihiko Noda stood in silence with hundreds of other people dressed in black at a memorial service.

"This is a difficult period but we must overcome it," Emperor Akihito said. "Many volunteers went to the devastated areas, living in tough conditions while supporting refugees. We must be thankful for them and those who worked to quell the nuclear disaster at the site."

The quake was the strongest recorded in Japan’s history, and set off a tsunami that towered more than 65 feet in some spots along the northeastern coast, destroying tens of thousands of homes and wreaking widespread destruction.

Naomi Fujino, a 42-year-old Rikuzentakata resident who lost her father in the tsunami, was in tears recalling last March 11.

With her mother, she escaped to a nearby hill where they watched the enormous wave wash away their home. They waited all night, but her father never came to meet them as he had promised. Two months later, his body was found.

"I wanted to save people, but I couldn’t. I couldn’t even help my father. I cannot keep on crying," Fujino said. "What can I do but keep on going?"

The tsunami also knocked out the vital cooling systems at the Fukushima Daiichi nuclear power plant, causing meltdowns at three reactors and spewing radiation into the air. Some 100,000 residents who were forced to flee remain in temporary housing or with relatives, and a 12-mile area around the plant is still off limits.

All told, some 325,000 people rendered homeless or evacuated are still in temporary housing. While much of the debris along the tsunami-ravaged coast has been gathered into massive piles, very little rebuilding has begun.

Beyond the massive cleanup, many towns are still finalizing reconstruction plans, some of which involve moving residential areas to higher ground. Bureaucratic delays in coordination between the central government, prefectural (state) authorities and local officials have also slowed rebuilding efforts.

A year after the disaster, police and other experts continue to search for the bodies of 3,155 people listed as missing, adding to the sense of loss for mourning relatives.

Anti-nuclear protesters at a downtown Tokyo park also held a moment of silence today before marching toward the headquarters of Tokyo Electric Power Co., the operator of the Fukushima nuclear power plant. Public opposition to atomic power has grown in the wake of the nuclear disaster, the worst since Chernobyl in 1986.

The government says the crippled Fukushima nuclear plant is stable and that radiation has subsided significantly, but the plant’s chief acknowledged to journalists visiting the complex recently that it remains in a fragile state, and makeshift equipment — some mended with tape — could be seen keeping crucial systems running.

Enormous risks and challenges lie ahead at the Fukushima plant, including locating and removing melted nuclear fuel from the inside of the reactors and disposing spent fuel rods. Completely decommissioning the plant could take 40 years.

Only two of Japan’s 54 reactors are now running, while those shut down for regular inspections undergo special tests to check their ability to withstand similar disasters. They could all go offline by the end of April amid local opposition to restarting them.

The Japanese government has pledged to reduce reliance on nuclear power, which supplied about 30 percent of the nation’s energy needs before the disaster, but says it needs to restart some nuclear plants during the transition period.

While no one has died from radiation exposure, residents are worried that the radiation might show up as cancer in coming years, particularly among children. Pilot efforts to make radiation-contaminated land around the plant inhabitable again have begun, using everything from shovels and high-powered water guns to chemicals that absorb radiation.

Prime Minister Noda has acknowledged failures in the government’s response to the disaster, being too slow in relaying key information and believing too much in "a myth of safety" about nuclear power.

Some train services in Tokyo halted temporarily as part of the memorial. Tokyu Corp., which operates bus and train services mainly in southwest Tokyo and Kanagawa prefecture, said it increased a planned stop to 4 minutes from 1 minute to allow passengers time for "silent prayers."

Similar memorial events took place throughout the devastated areas. National broadcaster NHK showed images of a service in Okuma Town, inside the no-go zone around the nuclear plant. Mourners in white protective clothing offered flowers and prayers at a roadside, televised pictures showed.

In Kesennuma, where city officials are embarking on a 10-year recovery plan to repair the city known for its fishing port and seafood processing, a Pillars of Light ceremony — three giant searchlights symbolizing hope, the future and indomitable spirit — will be broadcast over the Internet.

"What I’ve learned is that you still have to try to live life," said Takeyoshi Kidoura, the international business manager at Kidoura Shipyards in Kesennuma. "Many people have lost their families, but life has to go on."

In Rikuzentakata, 37-year-old Mika Hashikai, who lost both her parents in the tsunami, went around today leaving flowers at the former homes of her friends and neighbors. Her brother also lost his wife and daughter in the tsunami.

"I only wish for my brother’s happiness now that he’s lost everything and is alone," she said. "Maybe one day he can remarry and have children again."

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Foster reported from Tokyo. Bloomberg News contributed to this report.