(CBS/AP) RIKUZENTAKATA, Japan - People across Japan prayed and stood in silence on Sunday to remember the massive earthquake and tsunami that struck the nation one year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century.
In the devastated northeastern coastal town of Rikuzentakata, a siren sounded at 2:46 p.m. the exact time the magnitude-9.0 quake struck on March 11, 2011 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 the seaside town of Onagawa, people facing the sea pressed their hands together in silent prayer.
In Tokyo's National Theatre, Japan's Emperor Akihito and Empress Michiko led a national ceremony of mourning for the nearly 20,000 victims of last year's multiple disasters. CBS News' Lucy Craft reports that 1,200 people in attendance who had lost a loved one in the disaster paused for a moment of silence, at 2:46 p.m.
Prime Minister Yoshihiko Noda pledged maximum efforts to restore the disaster zones. He vowed that Fukushima Prefecture, the radiation-contaminated site of the nuclear accident, would become pristine once again.
Even in Tokyo's busy shopping district of Shibuya, pedestrians briefly stopped and fell silent before carrying on.
Noda recalled in a speech that the Japanese people have overcome disasters and difficulties many times in the past, and pledged to rebuild the nation and the area around the tsunami-stricken Fukushima nuclear plant so that the country will be "reborn as an even better place."
"Our predecessors who brought prosperity to Japan have repeatedly risen up from crises, every time becoming stronger," Noda said. "We will stand by the people from the disaster-hit areas and join hands to achieve the historic task of rebuilding."
The earthquake was the strongest recorded in Japan's history, and set off a tsunami that swelled to more than 65 feet in some spots along the northeastern coast, destroying tens of thousands of homes and bringing widespread destruction.
The tsunami also knocked out the vital cooling systems at the Fukushima Dai-ichi 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.
The emperor voiced concern about the difficulties of decontaminating the land around the plant.
"In order to make the area inhabitable again, we face the difficult problem of removing radiation," Akihito said in a brief address. "We shall not let our memory of the disasters fade, pay attention to disaster prevention and continue our effort to make this land an even safer place to live."
Naomi Fujino, a 42-year-old Rikuzentakata resident who lost her father in the tsunami, tearfully recalled 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 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 crying," Fujino said. "What can I do but keep on going?"
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.