Japan paused on Friday to mark five years since an offshore earthquake spawned a monster tsunami that left about 18,500 people dead or missing along its northeastern coast and sparked the worst nuclear disaster in a quarter century.

Emperor Akihito, Empress Michiko, Prime Minister Shinzo Abe and other participants at a national ceremony in Tokyo bowed their heads as did many residents across the affected region at 2:46 pm (0546 GMT) -- the exact moment on March 11, 2011 that the magnitude 9.0 quake struck under the Pacific Ocean.