The clock, stored in a Buddhist temple, was submerged by the tsunami on Japan's north-eastern coast that followed the devastating earthquake, which killed more than 18,000 people in March 2011.
Its owner, Bunshun Sakano, then tried to fix the clock, without success.
But when a smaller quake hit 10 years later, he says it began working again.
According to the Mainichi Shimbun newspaper, the spring-driven clock was stored in the Fumonji Temple in Yamamoto, in Japan's Miyagi region. Miyagi and neighbouring Fukushima were badly hit by the 2011 earthquake and tsunami.